Crown Ethers: Macrocyclic polyethers with the repeating unit of (-CH2-CH2-O)n where n is greater than 2 and some oxygens may be replaced by nitrogen, sulfur or phosphorus. These compounds are useful for coordinating CATIONS. The nomenclature uses a prefix to indicate the size of the ring and a suffix for the number of heteroatoms.Rotaxanes: Complex compounds in which a dumbbell shaped molecule is encircled by a macrocycle. They are named after rota (wheel) and axis (axle). Notation with a prefix is used to indicate the number of interlocked components. They have potential use in NANOTECHNOLOGY. Rotaxanes have been made with CYCLODEXTRINS and CYCLIC ETHERS.Crowns: A prosthetic restoration that reproduces the entire surface anatomy of the visible natural crown of a tooth. It may be partial (covering three or more surfaces of a tooth) or complete (covering all surfaces). It is made of gold or other metal, porcelain, or resin.Antimutagenic Agents: Agents that reduce the frequency or rate of spontaneous or induced mutations independently of the mechanism involved.Ethers, Cyclic: Compounds of the general formula R-O-R arranged in a ring or crown formation.Ether: A mobile, very volatile, highly flammable liquid used as an inhalation anesthetic and as a solvent for waxes, fats, oils, perfumes, alkaloids, and gums. It is mildly irritating to skin and mucous membranes.EthersEthylene Oxide: A colorless and flammable gas at room temperature and pressure. Ethylene oxide is a bactericidal, fungicidal, and sporicidal disinfectant. It is effective against most micro-organisms, including viruses. It is used as a fumigant for foodstuffs and textiles and as an agent for the gaseous sterilization of heat-labile pharmaceutical and surgical materials. (From Reynolds, Martindale The Extra Pharmacopoeia, 30th ed, p794)IndiaMetals, Alkaline Earth: Metals that constitute the group 2 (formerly group IIa) of the periodic table.Metals, Rare Earth: A group of elements that include SCANDIUM; YTTRIUM; and the LANTHANOID SERIES ELEMENTS. Historically, the rare earth metals got their name from the fact that they were never found in their pure elemental form, but as an oxide. In addition they were very difficult to purify. They are not truly rare and comprise about 25% of the metals in the earth's crust.Anions: Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.Silicon: A trace element that constitutes about 27.6% of the earth's crust in the form of SILICON DIOXIDE. It does not occur free in nature. Silicon has the atomic symbol Si, atomic number 14, and atomic weight [28.084; 28.086].Metals: Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)Methanol: A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.Metals, Alkali: Metals that constitute group 1(formerly group Ia) of the periodic table. They are the most strongly electropositive of the metals. Note that HYDROGEN is not considered an alkali metal even though it falls under the group 1 heading in the periodic table.Electron Spin Resonance Spectroscopy: A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.Soil Pollutants, Radioactive: Pollutants, present in soil, which exhibit radioactivity.Neurotransmitter Agents: Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.Macrocyclic Compounds: Cyclic compounds with a ring size of approximately 1-4 dozen atoms.Protons: Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.Rubidium: An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.Cations: Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.Cesium: A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.Textbooks as Topic: Books used in the study of a subject that contain a systematic presentation of the principles and vocabulary of a subject.Hydroxides: Inorganic compounds that contain the OH- group.Stevens-Johnson Syndrome: Rare cutaneous eruption characterized by extensive KERATINOCYTE apoptosis resulting in skin detachment with mucosal involvement. It is often provoked by the use of drugs (e.g., antibiotics and anticonvulsants) or associated with PNEUMONIA, MYCOPLASMA. It is considered a continuum of Toxic Epidermal Necrolysis.Calcium Hydroxide: A white powder prepared from lime that has many medical and industrial uses. It is in many dental formulations, especially for root canal filling.Aluminum Hydroxide: A compound with many biomedical applications: as a gastric antacid, an antiperspirant, in dentifrices, as an emulsifier, as an adjuvant in bacterins and vaccines, in water purification, etc.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Ethyl Chloride: A gas that condenses under slight pressure. Because of its low boiling point ethyl chloride sprayed on skin produces an intense cold by evaporation. Cold blocks nerve conduction. Ethyl chloride has been used in surgery but is primarily used to relieve local pain in sports medicine.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Amines: A group of compounds derived from ammonia by substituting organic radicals for the hydrogens. (From Grant & Hackh's Chemical Dictionary, 5th ed)Patents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Programming, Linear: A technique of operations research for solving certain kinds of problems involving many variables where a best value or set of best values is to be found. It is most likely to be feasible when the quantity to be optimized, sometimes called the objective function, can be stated as a mathematical expression in terms of the various activities within the system, and when this expression is simply proportional to the measure of the activities, i.e., is linear, and when all the restrictions are also linear. It is different from computer programming, although problems using linear programming techniques may be programmed on a computer.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Hydrogen: The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.Inorganic Chemicals: A broad class of substances encompassing all those that do not include carbon and its derivatives as their principal elements. However, carbides, carbonates, cyanides, cyanates, and carbon disulfide are included in this class.Chemical EngineeringEncyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)EncyclopediasPhosphorus: A non-metal element that has the atomic symbol P, atomic number 15, and atomic weight 31. It is an essential element that takes part in a broad variety of biochemical reactions.Marketing: Activity involved in transfer of goods from producer to consumer or in the exchange of services.Molecular Sequence Annotation: The addition of descriptive information about the function or structure of a molecular sequence to its MOLECULAR SEQUENCE DATA record.Sulfur Compounds: Inorganic or organic compounds that contain sulfur as an integral part of the molecule.Amino Acids, SulfurHeterocyclic Compounds: Ring compounds having atoms other than carbon in their nuclei. (Grant & Hackh's Chemical Dictionary, 5th ed)Foramen Ovale, Patent: A condition in which the FORAMEN OVALE in the ATRIAL SEPTUM fails to close shortly after birth. This results in abnormal communications between the two upper chambers of the heart. An isolated patent ovale foramen without other structural heart defects is usually of no hemodynamic significance.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Journal Impact Factor: A quantitative measure of the frequency on average with which articles in a journal have been cited in a given period of time.Publishing: "The business or profession of the commercial production and issuance of literature" (Webster's 3d). It includes the publisher, publication processes, editing and editors. Production may be by conventional printing methods or by electronic publishing.Bibliometrics: The use of statistical methods in the analysis of a body of literature to reveal the historical development of subject fields and patterns of authorship, publication, and use. Formerly called statistical bibliography. (from The ALA Glossary of Library and Information Science, 1983)Peer Review, Research: The evaluation by experts of the quality and pertinence of research or research proposals of other experts in the same field. Peer review is used by editors in deciding which submissions warrant publication, by granting agencies to determine which proposals should be funded, and by academic institutions in tenure decisions.Bacteriology: The study of the structure, growth, function, genetics, and reproduction of bacteria, and BACTERIAL INFECTIONS.Authorship: The profession of writing. Also the identity of the writer as the creator of a literary production.

Lead-selective membrane potentiometric sensor based on an 18-membered thiacrown derivative. (1/64)

A PVC-based membrane electrode for lead ions based on hexathia-18-crown-6-tetraone as membrane carrier was prepared. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The electrode showed a Nernstian response over a lead concentration range from 1.0 x 10(-6) to 8.0 x 10(-3) M at 25 degrees C, and was found to be very selective, precise and usable within the pH range 3.0-6.0. The electrode was successfully used as an indicator electrode in potentiometric titration of lead ions and in direct determination of lead in water samples.  (+info)

Selective transport of silver ion through a supported liquid membrane using hexathia-18-crown-6 as carrier. (2/64)

A facile supported liquid membrane (SLM) system for the selective and efficient transport of silver ion is introduced. The SLM used is a thin porous polyvinyldifluoride membrane impregnated with hexathia-18-crown-6 (HT18C6) dissolved in nitrophenyloctyl ether. HT18C6 acts as a specific carrier for the uphill transport of Ag+ ion as its picrate ion paired complex through the SLM. In the presence of thiosulfate ion as a suitable stripping agent in the strip solution, transport of silver occurs almost quantitatively after 4 h. The selectivity and efficiency of silver transport from aqueous solutions containing other Mn+ cations such as Mg2+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were investigated.  (+info)

Role of hypoxia during normal retinal vessel development and in experimental retinopathy of prematurity. (3/64)

PURPOSE: To test the hypothesis that retinal hypoxia is present during vascular development in normal rat pups and in a newborn rat model of retinopathy of prematurity (ROP). METHODS: Preretinal vitreous PO(2) measurements were made during room air breathing using (19)F magnetic resonance spectroscopy (MRS) and a perfluoro-15-crown-5-ether droplet in normal adult and newborn (postnatal day [P]1-P20) rats, and in newborn rats exposed first to 14 days of variable oxygen (before NV) and six additional days in room air after variable oxygen exposure (during NV). After each experiment, blood gas values were measured, and retinas were isolated. Retinas were adenosine diphosphatase (ADPase) stained, and flatmounted to determine peripheral avascular extent and NV incidence and severity. RESULTS: In the vascularized rat retina, no significant difference (P > 0.05) was found between the droplet-derived preretinal vitreous oxygen tension (24 +/- 2 mm Hg, mean +/- SEM, n = 18) and previously reported electrode-measured oxygen tension (22 +/- 1 mm Hg). Only during normal retinal vessel growth (P1-P10) and before the appearance of NV was evidence for retinal hypoxia found at the border of the vascular and avascular retina. However, the mean PO(2) (range, 24-28 mm Hg) over the vascular retina was not different (P > 0.05) between any of the newborn rat groups in this study. CONCLUSIONS: (19)F MRS of a perfluorocarbon droplet provides an accurate measure of preretinal vitreous oxygen tension in rats. These data support an important role of physiologic hypoxia in normal retinal circulatory development and raises the possibility that, in experimental ROP, retinal hypoxia is a necessary but not sufficient condition for the development of retinal NV.  (+info)

Selective molecular recognition of arginine by anionic salt bridge formation with bis-phosphate crown ethers: implications for gas phase peptide acidity from adduct dissociation. (4/64)

Arginine forms a stable noncovalent anionic salt bridge complex with DP (a crown ether which contains two endocyclic dialkylhydrogenphosphate esters). Abundant adduct formation with DP is observed for complexes with arginine, YAKR, HPPGFSPFR, AAKRKAA, RR, RPPGFSPFR, RYLGYL, RGDS, and YGGFMRGL in electrospray ionization mass spectrometry (ESI-MS) experiments. DFT calculations predict a hydrogen bonded salt bridge structure with a protonated guanidinium flanked by two deprotonated phosphates to be the lowest energy structure. Dissociation of DP/peptide adducts reveals that, in general, the relative gas phase acidity of a peptide is dependent on peptide length, with longer peptides being more acidic. In particular, peptides that are six residues or more in length can stabilize the deprotonated C-terminus by extensive hydrogen bonding with the peptide backbone. Dissociation of DP/peptide complexes often yields the deprotonated peptide, allowing for the facile formation of anionic peptides that otherwise would be difficult to generate in high abundance. Although DP has a preference for binding to arginine residues in peptides, DP is also observed to form less abundant complexes with peptides containing multiple lysines. Lys-Xxx-Lys and Lys-Lys sequences form low abundance anionic adducts with DP. For example, KKKK exclusively forms a double adduct with one net negative charge on the complex.  (+info)

Potentiometric determination of dopamine in pharmaceutical preparations by crown ether-PVC membrane sensors. (5/64)

Two simple, rapid and sensitive sensors for the assay of dopamine hydrochloride have been developed. The methods are based upon the formation of the membrane sensors 12-crown-4-phosphotungestic acid (crown ether-PTA)-dopamine and 12-crown-4-tetraphenylborate (crown ether-TPB)-dopamine as neutral carriers. The sensors were stable and showed fast potential responses of 10 s, and near-Nernstian cationic slopes of 53.3 - 56.2 mV/decade of activity between pH 2.2 - 6 for the monovalent dopamine cation over a wide range concentrations 1 x 10(-5) - 1 x 10(-1) M. The selectivity coefficients of the developed sensors indicated excellent selectivity for dopamine over a large number of organic and inorganic species and pharmaceutical excipients. The mediator o-nitrophenyloctyl ether significantly affected the lifetime of the fabricated sensors of dopamine. Satisfactory results were obtained for the determination of dopamine in dosage form by the proposed sensors with an average recovery of 99.85% for the nominal concentration.  (+info)

Field-dependent effect of crown ether (18-crown-6) on ionic conductance of alpha-hemolysin channels. (6/64)

Closing linear poly(ethylene glycol) (PEG) into a circular "crown" dramatically changes its dynamics in the alpha-hemolysin channel. In the electrically neutral crown ether (C2H4O)6, six ethylene oxide monomers are linked into a circle that gives the molecule ion-complexing capacity and increases its rigidity. As with linear PEG, addition of the crown to the membrane-bathing solution decreases the ionic conductance of the channel and generates additional conductance noise. However, in contrast to linear PEG, both the conductance reduction (reporting on crown partitioning into the channel pore) and the noise (reporting on crown dynamics in the pore) now depend on voltage strongly and nonmonotonically. Within the whole frequency range accessible in channel reconstitution experiments, the noise power spectrum is "white", showing that crown exchange between the channel and the bulk solution is fast. Analyzing these data in the framework of a Markovian two-state model, we are able to characterize the process quantitatively. We show that the lifetime of the crown in the channel reaches its maximum (a few microseconds) at about the same voltage (approximately 100 mV, negative from the side of protein addition) where the crown's reduction of the channel conductance is most pronounced. Our interpretation is that, because of its rigidity, the crown feels an effective steric barrier in the narrowest part of the channel pore. This barrier together with crown-ion complexing and resultant interaction with the applied field leads to behavior usually associated with voltage-dependent binding in the channel pore.  (+info)

Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal. (7/64)

Thermodynamic parameters of complexation of naphto-15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.  (+info)

A novel ternary ligand system useful for preparation of cationic (99m)Tc-diazenido complexes and (99m)Tc-labeling of small biomolecules. (8/64)

This report describes a novel ternary ligand system composed of a phenylhydrazine, a crown ether-containing dithiocarbamate (DTC), and a PNP-type bisphosphine (PNP). The combination of three different ligands with (99m)Tc results in cationic (99m)Tc-diazenido complexes, [(99m)Tc(NNAr)(DTC)(PNP)]+, with potential radiopharmaceuticals for heart imaging. Synthesis of cationic (99m)Tc-diazenido complexes can be accomplished in two steps. For example, the reaction of phenylhydrazine with (99m)TcO4- at 100 degrees C in the presence of excess stannous chloride and 1,2-diaminopropane-N,N,N',N'-tetraacetic acid (PDTA) results in the [(99m)Tc(NNPh)(PDTA)n] intermediate, which then reacts with sodium N-(dithiocarbamato)-2-aminomethyl-15-Crown-5 (L4) and N,N-bis[2-(bis(3-ethoxypropyl)phosphino)ethyl]ethoxyethylamine (PNP6) at 100 degrees C for 15 min to give the complex, [(99m)Tc(NNPh)(L4)(PNP6)]+ in high yield (>90%). Cationic complexes [(99m)Tc(NNPh)(DTC)(PNP)]+ are stable for > or = 6 h. Their composition was determined to be 1:1:1:1 for Tc:NNPh:DTC:PNP using the mixed-ligand experiments on the tracer ((99m)Tc) level and was further confirmed by the ESI-MS spectral data of a model compound [Re(NNPh)(L4)(L6)]+. It was found that both DTCs and bisphosphines have a significant impact on the lipophilicity of their cationic (99m)Tc-diazenido complexes. Results from a (99m)Tc-labeling efficiency experiment showed that 4-hydrazinobenzoic acid (HYBA) might be useful as a bifunctional coupling agent for (99m)Tc-labeling of small biomolecules. However, the (99m)Tc-labeling efficiency of HYBA is much lower than that of 6-hydrazinonicotinic acid (HYNIC) with tricine and trisodium triphenylphosphine-3,3',3''-trisulfonate (TPPTS) as coligands.  (+info)

Crown ethers are heterocyclic chemical compounds that consist of a ring containing several ether groups. The most common crown ethers are oligomers of ethylene oxide, the repeating unit being ethyleneoxy (-CH2CH2O-). Important members of this series are the tetramer (n = 4, or four ethyleneoxy units), the pentamer (n = 5), and the hexamer (n = 6). The term "crown" refers to the resemblance between the structure of a crown ether bound to a cation, and a crown sitting on a head. The first number in the name of a crown ether refers to the number of atoms in the cycle, and the second number refers to the number of those atoms that are oxygen. Crown ethers are much broader than the oligomers of ethylene oxide; an important group is derived from catechol.. Crown ethers strongly bind certain cations, forming complexes. The oxygen atoms are well situated to coordinate with a cation located within the ring, whereas the exterior of the ring is hydrophobic (repels water and polar and ionic substances). The ...
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We report the preparations and electron spin resonance (ESR) studies of a series of Cs+ and Rb+ crown ether (15-crown-5 and 18-crown-6) salts of [TcNCl4]- and [MoOCl4]-, and a new refinement of the X-ray structure of [Cs(18-crown-6)] [TcNCl4] involving a twinned P4/n scattering model. This refinement addresses some unsatisfactory aspects of the original disordered model. The structure consists of an infinite sandwich Cs+ cation/crown ether configuration and polymeric [TcNCL4]- anions, with Tc≡N distances of 1.561(36) Å, and anti-parallel chains of ---Tc≡N---Tc≡N ---with Tc···Tc separations of 4.275(4) Å. The structure determination of [Rb(15-crown-5)2][TcNCl4(OH2)] is also described and shows a lattice containing 2:1 sandwich-type crown ether/alkali-metal cations and isolated anions in the disordered lattice. The presence of Tc≡N infrared stretching frequencies at ca. 1074 cm-1 indicates the absence of strong electron donors coordinated to Tc in the sixth position (i. e. ...
TY - JOUR. T1 - New crown ethers containing Kemps triacid and their binding properties with alkali metal cations. AU - Jeong, Kyu Sung. AU - Kim, Jong Hyun. PY - 1996/12/1. Y1 - 1996/12/1. UR - http://www.scopus.com/inward/record.url?scp=18444365304&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=18444365304&partnerID=8YFLogxK. M3 - Article. AN - SCOPUS:18444365304. VL - 17. SP - 564. EP - 567. JO - Bulletin of the Korean Chemical Society. JF - Bulletin of the Korean Chemical Society. SN - 0253-2964. IS - 6. ER - ...
A bolaamphiphilic low-molecular-weight gelator based on crown ether, which could self-assemble into organogels and hydrogels, was prepared. The contribution of each part of the structure to the gelation property was investigated by designing a series of analogues. A simple framework (crown ether-hydrophobic
Abstract : A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1) s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related ...
The reaction of bismuth triiodide with iodine and benzo-15-crown-5 in ethanol/dichloromethane yielded red single crystals of (b15c5)BiI3(I2) (monoclinic, P21/c (no. 14), a = 1376.9(1), b = 1172.7(1), c = 1700.2(2) pm, b = 115.197(6), V = 2484.1(4)·106 pm3, Z = 4). Neutral pseudo-octahedral complexes (b15c5)BiI3 are connected by secondary bonding interactions via iodine molecules to chains. Electronic structure calculations of the neutral complex (b15c5)BiI3 reveal that the compound can indeed be described as b15c5 interacting with a molecular BiI3 unit. However, bonding has to be mainly electrostatic as the interactions of the bismuth 6s lone pair with the 2p orbitals of the oxygen atoms of the crown ether are clearly antibonding.
The novel laser desorption method laser-induced liquid beam ionization/desorption (LILBID) is applied to the mass spectrometric examination of selective ion binding by natural and synthetic ionophores in methanol solutions. The ions are desorbed from a liquid jet with an IR laser pulse and then extracted perpendicularly into a reflectron time-of-flight (RE-TOF) analyzer. LILBID studies on the natural ion carriers valinomycin and monensin A are presented, as well as those on the synthetic crown ethers 18-crown-6, diaza-18-crown-6, and benzo-15-crown-5. No fragment ions are detected, and the measured ion selectivity is in good qualitative agreement with published stability constants of the complexes. The observed specific recognition of silver ions by diaza-18-crown-6 can be rationalized by the principle of hard and soft acids and bases, which predicts stable complexes when the polarizabilities of Lewis acid and base are similar. Weak, noncovalent interactions like those in the sandwich complex ...
|p|Icotinib Hydrochloride is a potent and highly selective inhibitor of epidermal growth factor receptor tyrosine kinases (EGFR-TKI) with IC50 value of 5 nM.|br /|EGFR is an oncogenic driver which is expressed on the cell surface of normal cells and cance
Complexes of dibenzo-18-crown-6 (DB18C6, host) with water, ammonia, methanol, and acetylene (guest), formed in supersonic jets, have been characterized by using various spectroscopic methods: laser induced fluorescence (LIF), UV-UV hole-buning (UV-UV HB), and IR-UV double resonance (IR-UV DR) spectroscopy. Firstly, we reinvestigated the conformations of bare DB18C6 (species m1 and m2) and the structure of DB18C6-H2O (species a) [R. Kusaka, Y. Inokuchi, T. Ebata, Phys. Chem. Chem. Phys., 2008, 10, 6238] by measuring the IR-UV DR spectra in the region of the methylene CH stretching vibrations. From the IR-UV DR spectra, it was found that the IR spectral feature of the methylene CH stretch of DB18C6-H2O is clearly different from those of bare DB18C6 conformers, suggesting that DB18C6 changes its conformation when it forms the complex with a water molecule. With the aid of Monte Carlo simulation for extensive conformational search and density functional calculations (at B3LYP and M05-2X/6-31+G* ...
A variety of novel cage-functionalized pyridyl containing crown ethers have been prepared for use in selective alkali metal complexation studies. A highly preorganized, cage-functionalized cryptand also has been designed and has been synthesized for use as a selective Li+ complexant. The alkali metal picrate extraction profiles of these cage-functionalized crown ethers also have been studied. Novel cage-functionalized diazacrown ethers have been prepared for selective alkali metal complexation studies. Alkali metal picrate extraction experiments have been performed by using this new class of synthetic ionophores to investigate the effects of cage-annulation and the influence of N-pivot lariat sidearms upon their resulting complexation properties. Novel pyridyl containing calix[4]arene receptors were prepared. Analysis of their respective 1H NMR and 13C NMR spectra suggests that calix[4]arene moieties in the ligand occupy the cone conformation. The complexation properties of these host molecules were
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Macrocyclic molecules such as crown ethers have useful ion-binding properties, and their incorporation into a matrix can create materials with new properties, especially if these ring structures are left free for binding metals. Sharma and Clearfield have now found that derivatized crown ethers bearing a phosphonate group can self-assemble into well-defined "leaflet" structures in the presence of the divalent metal ions Co2+ and Cd2+. In the Co2+ complex (2), the metal does not coordinate with the phosphonates; the self-assembly proceeds through hydrogen bonding to form a polyphosphonate chain. In the Cd2+ complex, the Cd cations form part of a more complicated one-dimensional polymer network.-PDS. J. Am. Chem. Soc.122, 1558 (2000).. ...
Actually, anions are not unstable in organic phases per se. There is no intrinsic physical property of organic phases that would make anions inherently unstable: the main problem is that most heteroatoms in organic solvents are more electronegative than carbon and therefore carry a slightly negative charge which attracts cations more easily than anions.. Most organic phases are best classified as ionophobe, however. They will not like cations or anions in their vicinity. Remember that organic phases are typically mainly hydrocarbons with the odd heteroatom, so they have a low polarisablility. Water, on the other hand, is a highly polarised dipole and able to stabilise both cations and anions easily with the appropriate side of the water molecule.. Now if we add a phase transfer catalyst to a biphasic mixture of water and an organic solvent - typical examples would be $\ce{Bu4N+ I-}$ or crown ethers - then these will readily transfer themselves into the organic phase. In the case of crown ethers, ...
Calculated speciation curves for (a) 3,5-dnba and (b) 4-aba in methanol. Lines between points have been added as a guide to the eye. ...
... is approved for the treatment for EGFR mutation-positive, advanced or metastatic non-small cell lung cancer (NSCLC). Upon initial approval, icotinib was indicated as a second-line or third-line treatment for patients who have failed at least one prior treatment with platinum-based chemotherapy. In 2014, icotinib was approved to treat NSCLC patients with EGFR mutation regardless of past chemotherapy use.[6] The ICOGEN trial was a double-blind, head-to-head phase III study comparing icotinib with gefitinib in all-comers. From 27 centers in China, 399 patients were randomized between the two treatments testing for a primary objective of progression-free survival and secondary objectives of overall survival, time to progression, quality of life, percentage of patients who achieved an objective response, and toxic effects. The ICOGEN results showed icotinib to have a median PFS of 4.6 months (95% CI 3.5 - 6.3) as compared to gefitinib which has a PFS of 3.4 months (95% CI 2.3 - 3.8). After ...
A novel fluorescent pH sensor with tunable response range was designed based on highly fluorescent 3,4:9,10-perylene tetracarboxylic ammonium, which could coordinate the paramagnetic Fe(3+) ions to turn off its fluorescence and could also release Fe
Process for the preparation of compounds of the formula (1) ##STR1## in which R.sub.1 denotes a phenyl or naphthyl radical which can be substituted by alkyl, cycloalkyl, alkoxy, aryloxy, arylazo or nitro groups or halogen atoms, and R.sub.2 denotes a hydrogen atom or a phenyl or naphthyl radical which can be substituted by alkyl, cycloalkyl, alkoxy, aryloxy, arylazo or nitro groups or halogen atoms, or denotes an alkyl (C.sub.1 -C.sub.8) radical, by condensation, at between 100.degree. C. and 300.degree. C., of perylene-3,4,9,10-tetracarboxylic dianhydride or a monoanhydride monoimide of the formula (2) ##STR2## in which R.sub.2 has the abovementioned meaning, with an arylamine of the formula (3)in which R.sub.1 has the abovementioned meaning, in the presence of dialkylamines of the formula (4) ##STR3## in which R and R
Level 1: Standard whole brain radiation therapy plus icotinib 125 mg Tid (375 mg per day) from day1 until disease progression or intolerable toxicity.. Level 2: Standard whole brain radiation therapy plus icotinib 250 mg Tid (750 mg per day) from day1 until disease progression or intolerable toxicity.. Level 3: Standard whole brain radiation therapy plus icotinib 375 mg Tid (1125 mg per day) from day1 until disease progression or intolerable toxicity.. Level 4:Standard whole brain radiation therapy plus icotinib 500 mg Tid (1500 mg per day) from day1 until disease progression or intolerable toxicity. ...
Theoretical Study on the Extraction of Alkaline Earth Salts by 18-Crown-6: Roles of Counterions, Solvent Types and Extraction Temperatures
A set of four hybrid host-guest complexes based on the inorganic crown ether analogue [H12W36O120]12− ({W36}) have been isolated and characterised. The cluster anion features a central rigid binding site made up of six terminal oxygen ligands and this motif allows the selective binding of a range of alkali and alkali-earth-metal cations. Here, the binding site was utilised to functionalise the metal oxide-based cavity by complexing a range of protonated primary amines within the recognition site. As a result, a set of four hybrid organic-inorganic host-guest complexes were obtained whereby the interactions are highly directed specifically within this cavity. The guest cations in these molecular assemblies range from the aromatic 2-phenethylamine (1) and 4-phenylbutylamine (2) to the bifunctional aromatic p-xylylene diamine (3) and the aliphatic, bifunctional 1,6-diaminohexane (4). Compounds 1-4 were structurally characterised by single-crystal X-ray diffraction, elemental analysis, flame ...
The first part of this work deals with the interactions of amino acids and neutral macrocyclic ligands (18-crown-6 and cryptand 222). Solubilities and Gibbs energies of solution of several amino acids and their complexes with 18-crown-6 in acetonitrile, as well as of some amino acid ester salts in chloroform have been determined at 298.15 K. An increase in the solubility data for the amino acid complexes relative to the free amino acids has been found, as a result of the interactions of the guest molecules with the macrocyclic ligands. Stability constants, Gibbs energies, enthalpies and entropies of complexation of a series of L- and D-amino acids with 18-crown-6 and with cryptand 222 in methanol at 298.15 K were obtained by titration calorimetry. The similar Gibbs energies of complexation found for these systems are the result of an enthalpy-entropy compensation effect. No significant differences have been found between the thermodynamic parameters of complexation of the L- and D-amino acids ...
A general review on macrocyclic ligands with particular emphasis to dibenzocryptand 222 and dibenzo 18 crown 6 is given in the first part of the thesis (Chapter 1). This is followed by an exhaustive literature survey on the stability constants (hence free energies of complexing), enthalpies and entropies of metal cations with cryptands (dibenzocryptand 222, benzocryptand 222, cryptand 222) and crown ethers (dibenzo 18 crown 6, benzo 18 crown 6, 18 crown 6) in water and in non-aqueous solvents at 298.15 (Chapter 2). The experimental part (Chapter 3) also includes a detailed description of the principals involved in calorimetry as well as the methods used for the calculation of reaction enthalpies. Stability constant data for alkali-metal and silver cations with dibenzocryptand 222 in five dipolar aprotic solvents (N,N dimethyl-formamide, dimethylsulphoxide, acetonitrile, propylene carbonate and nitromethane) at 298.15 K are reported. These data are used to calculate the standard free energies of ...
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice ...
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice ...
0066] In a preferred embodiment of this application, the chelating agent employed for the preparation of solvent based compositions is selected from the group comprising polyols, gluconates, sorbitals, mannitols, carbonates, heptonates, hydroxamates, catechols, α-amino carboxylates, alkanolamines, metal-ion sequestrants, hydroxy-carboxylic acids, aminocarboxylic acids, amino polycarboxylic acids, polyamines, polyphosphates, phosphonic acids, crown ethers, amino acids, polycarboxylic acids, cyclodextrin, phosphonates, polyacrylates or polymeric polycarboxylates and condensed phosphates. However, the particular sequestering or chelating agents of the present application would include but are not limited to acetic acid, adenine, adipic acid, ADP, alanine, alanine, albumin, arginine, ascorbic acid, asparagine, aspartic acid, ATP, benzoic acid, n-butyric acid, casein, citraconic acid, citric acid, cysteine, dehydracetic acid, desferri-ferrichrysin, desferri-ferrichrome, desferri-ferrioxamin E, ...
A method and apparatus for detecting contaminants in an aqueous flow. The method includes the steps of providing a conduit having at least one collection portion upon which is disposed a selective film, disposing the aqueous flow through the conduit, attracting contaminants to the collection portion such that they are bonded to the selective film, and detecting a contaminant, or contaminants, based upon a predetermined property of the plurality of contaminants bonded to the ion collection portion. The selective film may include a molecularly imprinted polymer, a crown ether, an antibody selective for biological contaminants, such as Giardia Lamblia and cryptosporidia, or for detecting organics such as dioxin or furan, a cyclodextrin, or a cyclophane. The apparatus includes a conduit having an collection portion with a selective film disposed thereon, a sensor that senses contaminants collected on the collection portion and sends a signal corresponding to a value of a predetermined property of the
A binucleating ligand has been prepared that contains an SCS pincer and three oxygen donor atoms in a partial crown ether loop. To enable metalation with Ni0, a bromoarene precursor was used and resulted in the formation of a nickel-bromide complex in the SCS pincer portion of the ligand. Reaction of the nic
Page contains details about N,N-(dicyclohexyl) perylene-3,4,9,10-tetracarboxylic diimide-coated titanium dioxide nanotube arrays . It has composition images, properties, Characterization methods, synthesis, applications and reference articles : nano.nature.com
High nitrogen materials are sought as a potentially dense, powerful but insensitive explosive and propellant ingredients. Elucidation of the structure and chemistry of dibenzo-1 ,3a,4,6a-tetraazapentalenes has continued, with particular attention to a putative C12N12O12 derivative initially prepared at the University of New Orleans. This research contributed substantially to identification of the actual o-quinone hydrate structure, and explanation of the apparently anomalous explosive insensitivity of the material. Synthesis of the novel 5,7-dinitrobenzo-1 ,2,3,4-tetrazine-1,3-dioxide has been repeated, its structure has been confirmed, and preliminary evaluation of its explosive sensitivity has been completed.*NITROGEN
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This week, I made a birthday crown for Ember. It was a rare opportunity... As my sons primary caregiver, I do most of my crafting in the spaces between
Our research program uses fundamental principles of molecular design to address some of the grand challenges in the fields of small molecule activation and catalysis. We are interested in developing strategies to reversibly store energy in the form of chemical bonds, and also to rapidly convert abundant chemical (bio)feedstocks into value-added chemicals and fuels.. The overarching themes of our research program are to (a) understand how to exploit carefully positioned secondary-sphere sites to control reactivity, and (b) develop transition metal compounds to promote otherwise difficult transformations of small molecule chemical feedstocks such as N2, CO2, O2, and CO.. We are working to establish new ways by which molecular catalysts can be tuned by the incorporation of pendent functional groups within a metals secondary coordination sphere environment. We are using these appended functional groups (hydrogen bond donor/acceptors, or Lewis acid/bases) to augment reactivity of the central ...
5-AMINO-3-SULFOSALICYLIC ACID | C7H7NO6S | CID 22574 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.
TY - JOUR. T1 - Separation properties of surface modified silica supported liquid membranes for divalent metal removal/recovery. AU - Cooper, C. A.. AU - Lin, Y. S.. AU - Gonzalez, M.. PY - 2004/2/1. Y1 - 2004/2/1. N2 - The synthesis and separation properties of a mesoporous silica supported liquid membrane (SLM) were studied. The membranes consisted of a silica layer, from dip-coated colloidal silica, on an α-alumina support, modified with dichlorodimethyl silane (DCDMS) to add surface methyl groups to the silica layer. 2-Hydroxy-5-nonylacetophenome oxime (LIX-84) was entrapped within the pores of the silica due to hydrophobic interactions between the surface methyl groups and the long hydrocarbon chain from the LIX-84. The goal of synthesizing the membrane in this manner was to enhance the stability of SLMs. The membranes made after two-time dip-coating demonstrated good stability (no sign of LIX loss after 12 days) and uphill Cu2+ transport against the concentration gradient. Regardless of ...
Triboelectric nanogenerators are an energy harvesting technology that relies on the coupling effects of contact electrification and electrostatic induction between two solids or a liquid and a solid. Here, we present a triboelectric nanogenerator that can work based on the interaction between two pure liquids. A liquid-liquid triboelectric nanogenerator is achieved by passing a liquid droplet through a freely suspended liquid membrane. We investigate two kinds of liquid membranes: a grounded membrane and a pre-charged membrane. The falling of a droplet (about 40 μL) can generate a peak power of 137.4 nW by passing through a pre-charged membrane. Moreover, this membrane electrode can also remove and collect electrostatic charges from solid objects, indicating a permeable sensor or charge filter for electronic applications. The liquid-liquid triboelectric nanogenerator can harvest mechanical energy without changing the object motion and it can work for many targets, including raindrops, irrigation
Aspergillomarasmine A is an polyamino acid naturally produced by the mold Aspergillus versicolor. The substance has been reported to inhibit two antibiotic resistance carbapenemase proteins in bacteria, New Delhi metallo-beta-lactamase 1 (NDM-1) and Verona integron-encoded metallo-beta-lactamase (VIM-2), and make those antibiotic-resistant bacteria susceptible to antibiotics. Aspergillomarasmine A is toxic to leaves of barley and other plants, being termed as "Toxin C" when produced by Pyrenophora teres. The molecule is a tetracarboxylic acid with four -COOH groups. One section of the molecule is the amino acid aspartic acid. This has two alanine[contradictory] molecules attached. Aspergillomarasmine B differs in that the last alanine is replaced by glycine. The crystalline substance was first isolated in 1956, but its name was given until 1965. In addition to Aspergillus versicolor, aspergillomarasmine A is also produced by the ascomycete Pyrenophora teres where it acts as a toxin in the barley ...
Perylene-3,4,9,10-tetracarboxylic acid diimides of the formula I ##STR1## in which R is a linear or branched alkylene, alkylenecycloalkylene or cycloalkylenealkylene radical which has at least 15 C atoms and which is interrupted by one or two --COO--, --OOC--, --CONH-- and/or --NHCO-- groups, and Z is hydrogen, hydroxyl or a --COOH group. Perylene diimides of this type are excellently suitable for coloring polyolefins. In this regard, they are particularly distinguished by their low tendency to bloom. They are also very suitable for coloring engineering plastics, in which they produce fluorescent colorations having a high fluorescence and excellent fastness to heat, light and weathering.
A phosphate-free automatic dishwashing cleaning composition comprising a crystal growth inhibitor system comprising cyclohexane-1,2,3,4,5,6-hexacarboxylic acid (CHHCA) and cyclopentane-1,2,3,4-tetracarboxylic acid (CPTCA).
Page contains details about film of 3,9-di(9H-carbazol-9-yl)benzo-[d]benzo[4,5]imidazo[2,1-b]thiazole doped with 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-diphenyl-9,10-dihydroacridine . It has composition images, properties, Characterization methods, synthesis, applications and reference articles : nano.nature.com
TY - JOUR. T1 - Surface and optical properties of Langmuir and LB films of a crown-ether C60 derivative. AU - Wang, Shaopeng. AU - Leblanc, Roger. AU - Arias, Francisco. AU - Echegoyen, Luis. PY - 1997/3/19. Y1 - 1997/3/19. N2 - The Langmuir and Langmuir-Blodgett films of a benzo-18-crown-6-methanofullerene (1) were studied by spectrophotometry and Brëwster angle microscopy. The surface pressure-area isotherm of the C60 derivative (1) was obtained, and the compressibility of the isotherms was calculated. The addition of KCl to the water subphase stabilized the monolayer and increased the limiting area per molecule from 84 to 101 Å, which is near the theoretical value. The changes of the Langmuir monolayer UV-vis spectra as a function of time are considered to be due to fullerene aggregation. Polymerization was not detected upon UV irradiation, in contrast to what has been reported in the literature. Brëwster angle microscopy shows different aggregation properties of the ...
Sika Acquires Technology Leader in Liquid Membranes Sika AG has acquired Iotech Group Limited, with headquarters in England and subsidiaries in the UK, U.S. and Belgium. Iotech Group revenues totaled $55 million for the year 2008. Iotech specia
Self-assembled phthalocyanine-multifullerene donor-acceptor conjugates have been formed by crown ether-ammonium cation dipole-ion binding strategy to probe the photochemical charge separation. To achieve this, phthalocyanine is functionalized to possess four 18-crown-6 moieties on the macrocycle periphery, whereas fullerene is functionalized to possess an alkyl ammonium cation of short and long chain lengths. Stable donor-acceptor conjugates accommodating multifullerene entities have been obtained by the crown ether-ammonium cation inclusion complexation. From the efficient fluorescence quenching of the zinc phthalocyanine by the bound fullerene entities, the rate constants of charge separation are evaluated to be slightly larger for closely held via shorter alkyl chain length fullerene, which are also larger compared to the earlier reported analogous zinc porphyrin-multifullerene conjugate. Nanosecond transient absorption studies yielded spectral signatures corresponding to both the ...
Heteroligand Co(II) complexes involving imidazole and selected bio-relevant L-α-amino acids of four different groups (aspartic acid, lysine, histidine and asparagine) were formed by using a polymeric, pseudo-tetrahedral, semi-conductive Co(II) complex with imidazole-[Co(imid)2]n as starting material. The coordination mode in the heteroligand complexes was unified to one imidazole in the axial position and one or two amino acid moieties in the appropriate remaining positions. The corresponding equilibrium models in aqueous solutions were fully correlated with the mass and charge balance equations, without any of the simplified assumptions used in earlier studies. Precise knowledge of equilibria under oxygen-free conditions would enable evaluation of the reversible oxygen uptake in the same Co(II)-amino acid-imidazole systems, which are known models of artificial blood-substituting agents. Heteroligand complexes were formed as a result of proton exchange between the two imidazole molecules found in the
A series of five title complexes was investigated spectroscopically in glasses at 77 K. Absorption and emission measurements revealed that the lowest singlet charge-transfer state moves closer in energy to both the ligand triplet and the charge-transfer triplet as the basicity of the phosphine ligands increases. The result is accompanied by a change in the relative distribution of the emissions from the latter two states. As the states become closer in energy the rate of internal conversion between singlets of disparate electronic configurations becomes slower. This is a key feature of the proposed model for this optical behavior. Consequently, intersystem crossing becomes competitive with internal conversion leading to changes in the relative yields of ligand and charge-transfer phosphorescence ...
Agnostic.Front-/-Akercocke-/-Alien.Weaponry-/-Amon.Amarth-/-Anaal.Nathrakh-/-Animals.As.Leaders-/-Behemoth-/-Between.The.Buried.And.Me-/-Black.Crown.Initiate-/-Black.Star.Riders-/-Body.Count-/-Candiria-/-Combichrist-/-Dark.Angel-/-Death.DTA-/-Deicide-/-Dethklok-/-DRI-/-Entombed-/-Evile-/-Fear.Factory-/-Frog.Leap-/-Godflesh-/-Gojira-/-Green.Carnation-/-Gutalax-/-Hatebreed-/-Iron.Reagan-/-Jungle.Rot-/-KMFDM-/-Kvelertak-/-Lost.Society-/-Loudblast-/-Manowar-/-Melechesh-/-Memoriam-/-Mercyful.Fate-/-Ministry-/-M.O.D.-/-Morbid.Angel-/-Morgoth-/-Municipal.Waste-/-My.Dying.Bride-/-Nails-/-Nuclear.Assault-/-Pig.Destroyer-/-Power.Trip-/-Protector-/-Rivers.Of.Nihil-/-Sacred.Reich-/-Saxon-/-Six.Feet.Under-/-Sleep-/-Stormtroopers.of.Beer-/-Suicidal.Tendencies-/-Tankard-/-Terrorizer-/-The.Crown-/-The.Great.Old.Ones-/-The.Zenith.Passage-/-Thin.Lizzy-/-Triptykon-/-Trust-/-Tsjuder-/-Twelve.Foot.Ninja-/-Twilight.Of.The.Gods-/-UFO-/-Upon.A.Burning.Body-/-Wrath-/-Xibalba-/-Zeal.&.Ardor ...
Conformational and vibrational analysis of 18-crown-6-alkali metal viagra vs cialis cation complexes. The FC of Na is a simple, noninvasive, and cost-effective method that can be used to evaluate recovery of renal function.. A phosphopeptide antibody was generated that specifically recognizes Snf1 over the counter viagra protein that is phosphorylated in its activation loop on threonine 210. Depression and disability: comparisons with common physical conditions in the Ibadan study of aging. Pre-emptive kidney transplants have not been favored in some centers because of concern about possible increased noncompliance and allegedly inferior long-term results.. There were differences in femoral stem revision, estimated blood viagra generic availability loss, and hospital stay. These observations are discussed in relation to the toxicity of Cd, and possible mechanisms of induction of the GJIC-related alterations are presented.. No significant changes in the duration of QT interval and corrected QT ...
Barham, Joshua P and Coulthard, Graeme and Kane, Ryan G and Delgado, Nathan and John, Matthew P and Murphy, John A (2016) Double deprotonation of pyridinols generates potent organic electron donor initiators for haloarene-arene coupling. Agewandte Chemie-International Edition, 55. pp. 4492-4496. ISSN 1433-7851 Xie, Hai-nan and Stevenson, Ross and Stone, Nicholas and Hernandez-Santana, Aaron and Faulds, Karen and Graham, Duncan (2012) Tracking bisphosphonates through a 20 mm thick porcine tissue by using surface-enhanced spatially offset raman spectroscopy. Agewandte Chemie-International Edition, 51 (34). pp. 8509-8511. ISSN 1433-7851 Balloch, Liam and Garden, Jennifer A. and Kennedy, Alan and Mulvey, Robert E. and Rantanen, Toni and Robertson, Stuart D. and Snieckus, Victor (2012) Dizincation of a 2-substituted thiophene : constructing a cage with a [16]crown-4 zincocyclic core. Agewandte Chemie-International Edition, 51 (28). pp. 6934-6937. ISSN 1433-7851 Wright, Iain A. and Kanibolotsky, ...
Biotransformation and biodegradation of chemical compounds are the major processes which determine the fate of organic compounds in aquatic and terrestrial environments. The susceptibility of a...
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Cryptands are a family of synthetic bi- and polycyclic multidentate ligands for a variety of cations. The Nobel Prize for Chemistry in 1987 was given to Donald J. Cram, Jean-Marie Lehn, and Charles J. Pedersen for their efforts in discovering and determining uses of cryptands and crown ethers, thus launching the now flourishing field of supramolecular chemistry. The term cryptand implies that this ligand binds substrates in a crypt, interring the guest as in a burial. These molecules are three-dimensional analogues of crown ethers but are more selective and strong as complexes for the guest ions. The resulting complexes are lipophilic. The most common and most important cryptand is N[CH2CH2OCH2CH2OCH2CH2]3N; the formal IUPAC name for this compound is 1,10-diaza-4,7,13,16,21,24-hexaoxabicyclo[8.8.8]hexacosane. This compound is termed [2.2.2]cryptand where the numbers indicate the number of ether oxygen atoms (and hence binding sites) in each of the three bridges between the amine nitrogen "caps". ...
The focus of this thesis is the incorporation of the 1,2-bis(pyridinium)ethane motif into new [2]rotaxane ligands for the purpose of developing new metal organic rotaxane frameworks (MORFs). Both new stoppers that can act as ligands as well as new crown ethers with appended donors were synthesized and these components combined to create new [2]rotaxane ligands and eventually new MORFs. Chapter 2, looks at the synthesis and coordination chemistry of a [2]rotaxane containing terpyridine stoppers. The [2]rotaxane was shown to form mixed ligand complexes with RuII, AgI, ZnII, and PdII. The complexes were studied in solution by NMR, and UV/vis spectroscopy and mass spectrometry and in the solid state by X-ray crystallography. Chapter 3 and 4, focuses on the synthesis of new tetrasubstituted dibenzo-24-crown-8 ethers and their inclusion into [2]pseudorotaxanes and [2]rotaxanes. The new [2]pseudorotaxanes and [2]rotaxanes were characterized in solution by NMR spectroscopy and mass spectrometry and in the solid
Headline: Bitcoin & Blockchain Searches Exceed Trump! Blockchain Stocks Are Next!. HTF Market Intelligence released a new research report of 108 pages on title Global Sulfosalicylic Acid Sodium Salt Sales Market Report 2017′ with detailed analysis, forecast and strategies.. Summary. In this report, the global Sulfosalicylic Acid Sodium Salt market is valued at USD XX million in 2016 and is expected to reach USD XX million by the end of 2022, growing at a CAGR of XX% between 2016 and 2022.. Request a sample report @ https://www.htfmarketreport.com/sample-report/269645-global-sulfosalicylic-acid-sodium-salt-sales-market. Report Highlights. Geographically, this report split global into several key Regions, with sales (volume), revenue (value), market share and growth rate of Sulfosalicylic Acid Sodium Salt for these regions, from 2012 to 2022 (forecast), covering. United States. China. Europe. Japan. Southeast Asia. India. Buy this report @ ...
This invention describes a new concept of flexible template-directed microporous partially pyrolyzed polymeric membranes which have greatly improved performance in separation of gas pairs compared to their precursor polymeric membranes. Organic hosts, such as crown ethers, cyclodextrins (CDs), calixarenes (CXs), and spherands, or polymeric additives, such as poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) were used as the micropore-forming templates. Micropore-forming template/polymer blend membranes comprising organic micropore-forming templates embedded in a polymer matrix were prepared by dissolving the organic micropore-forming templates in the polymer solution followed by solution-casting and solvent evaporation or solvent exchange. Low-temperature selectively pyrolyzing micropore-forming templates in the micropore-forming template/polymer blend membranes at a nitrogen flow resulted in the formation of flexible microporous partially pyrolyzed polymeric membranes.
Compared with previous 1H MRI approaches for visualizing the infiltration of immunocompetent cells into inflamed areas by use of superparamagnetic iron oxide particles, the method presented here has the advantage of a direct positive detection of the tagging agent and therefore has the potential to work also in tissues that generally appear very dark in 1H MRI such as the lungs. Although techniques have recently been described to image superparamagnetic iron oxide particles with a bright contrast,18 the physical basis of detection is still the disturbance of the regional magnetic field by these particles. Therefore, it often remains difficult to unequivocally assign alterations in local contrast to accumulating superparamagnetic iron oxide particles. Furthermore, iron-based contrast agents are readily metabolized, whereas the fluorinated crown ether used in this study is biologically inert and cannot easily be degraded. The reason is the very stable C-F bond and the dense electron cloud of the ...
Download summary (PDF). 1. Professor Alexandru T. Balabans 75th anniversary. Download Art 1 (PDF). 1.-bis Addendum to Professor Balabans List of Publications. Download Art 1-bis (PDF). 2. Horia PETRIDE, Oana COSTAN, Cristina FLOREA and Silvia UDREA. Competitive amide hydrolysis in mono- and diformylated ethylenediamines. Download Art 2 (PDF). Key words: amides, hydrolysis. 3. Florea DUMITRAŞCU, Constantin DRĂGHICI, Daniela VULUGA and Miron Teodor CĂPROIU. New pyrazoles by 1,3-dipolar cycloaddition reactions between sydnones and activated alkynes. Download Art 3 (PDF). Key words: sydnones, pyrazoles, 1,3-dipolar cycloaddition, regioselectivity, NMR spectroscopy. 4. Rodica Daniela BĂRĂŢOIU, Anca Elena BARBU, Lucia MUTIHAC, Miron Teodor CĂPROIU, Constantin DRĂGHICI, Radu SOCOTEANU and Titus CONSTANTINESCU. 4-(3-(phtalhydrazide)azo)N-phenylaza-15-crown-5. Synthesis and properties. Download Art 4 (PDF). Key words: luminol, N-phenylaza-15-crown-5, luminol derivative, 1H- and 13CNMR spectra ...
The enzyme Purple Acid Phosphatase (PAP) is an important target for the development of new anti-osteoporotic drug leads. The major goal of this thesis is to better emulate the synergy that occurs between the primary and secondary coordination sphere within the active site of phosphatase enzymes, such as PAP. This was perceived by development of synthetic methods for new biomimetics, i.e. low-molecular weight metal complexes. Therefore, asymmetric dinucleating ligands which mimic the peptide backbone of the active site of PAP including the ability to form hydrogen bonds with a phosphoester substrate or a nucleophile were designed and synthesized. Using these ligands, more accurate model systems for the enzyme active site were achievable as they combine the two essential structural features known to influence the catalytic activity towards the hydrolysis of phosphoesters, i.e. the asymmetry of the dinuclear active site and the capacity for hydrogen bond formation. The latter was verified by the
Separation of Aromatic Compounds from Hydrocarbon Mixtures by Vapor Permeation Using Liquid Membranes with Ionic LiquidsSeparation of Aromatic Compounds from Hydrocarbon Mixtures by Vapor Permeation Using Liquid Membranes with Ionic Liquids ...
Polyimides having high thermal and oxidative stability are prepared by the reaction, with application of heat, of a mixture of monomers comprising (a) a dialkyl or tetraalkyl ester of an aromatic tetracarboxylic acid, (b) an aromatic diamine, and (c) a monoalkyl or dialkyl ester of a dicarboxylic acid wherein the ratio of a:b:c is n:(n+1):2, wherein n has a value of from 1 to 20. The mixture of monomers is prepared in a 30 to 70 percent by weight solution of an organic solvent, a substrate impregnated with the solution and heated at 50 DEG to 205 DEG C to remove said solvent and form a low molecular weight prepolymer, and thereafter heated at 275 DEG to 350 DEG C to cure to a high molecular weight polyimide. In a specific embodiment, graphite fiber is impregnated with a solution of 60 percent by weight of a mixture of 2,5-dicarbomethoxyterephthalic acid, methylenedianiline, and 5-norbornene-2,3-dicarboxylic acid monomethyl ester in dimethyl formamide, the impregnated fiber heated at 50 DEG to 120 DEG C
Sentence Examples with the word ethane: Aronheim, Ann., 1874, 171, p. 219); and by the action of ortho-xylylene bromide on sodium ethane tetracarboxylic ester, the resulting tetra-hydronaphthalene tetracarboxylic…
Kinetics of Cr(III) ions transport through a bulk liquid membrane containing dinonylnaphthalenesulfonic acid (DNNSA) as a carrier, flowing over aqueous phases, has been examined. Special attention has been paid to the effect of the membranes velocity flow on the chromium concentration decrease in a feed phase. For the description of relationships of chromium(III) concentration in particular phases with the time, a model based on the assumption of consecutive first-order reactions was proposed. Satisfactory compatibility of experiments and model results have been obtained both for the membrane flow velocities below 0.0034 m·s-1 when the interfaces begin to fluctuate slightly and for low initial Cr(III) concentration in the feed phase.
TY - CONF. T1 - Supported liquid membrane permeation for selective lactic acid recovery. AU - Kienberger, Marlene. AU - Mungma, Nuttakul. AU - Siebenhofer, Matthäus. PY - 2017/11/8. Y1 - 2017/11/8. N2 - 1. IntroductionLactic acid is handled as a future bulk chemical due the use for poly lactic acid production. State of the art production for lactic acid is fermentation followed by precipitation and hydrolysis. Much attention has been drawn to the optimization of the fermentation as well as the downstream processing, however the best solutions has not been found yet [1]. Besides the state of the art production lactic acid is present in aqueous effluent from the pulping industry [2]. Following the biorefinery approach, valuables from the black liquor in pulping process may lead to a biorefinery including the carboxylic acids formic acid and acetic acid as well as lactic acid as valuables. This approach is applied in textile fiber production since long, but is new for the cellulose production. The ...
Tristani, E. M.; Wirgau, J. I.; Dubay, G. R.; Sibert, J. W.; Crumbliss, A. L. "Siderophore-redox active ionophore host-guest assemblies: A prototype for selective metal ion compartmentalization," Inorg. Chim. Acta 2010, 363(13), 3611-3615.. Clare, J. P.; Statnikov, A.; Lynch, V.; Sargent, A. L.; Sibert, J. W. "Wurster-Type Ureas as Redox-Active Receptors for Anions," J. Org. Chem. 2009, 74, 6637-6646.. DeBacker, M.; Hureau, M.; Depriester, M.; Deletoille, A.; Sargent, A. L.; Forshee, P. B.; Sibert, J. W. "On the Oxidation of Wursters Reagent and the Wursters Crown Analog of 15-Crown-5 in the Presence of Alkali Metal Cations," J. Electroanal. Chem. 2008, 612, 97-104.. Sibert, J. W.; Forshee, P. B.; Hundt, G. R.; Sargent, A. L.; Bott, S. G.; Lynch, V. "Wursters Crowns: A Comparative Study of ortho- and para-Phenylenediamine-Containing Macrocyclic Receptors," Inorg. Chem. 2007, 46, 10913-10925.. Sibert, J. W.; Forshee, P. B.; Lynch, V. Electron Transfer vs. Coordination Chemistry: ...
A sensor (10) is provided for detecting the concentration of potassium ions which comprises a molecule which selectively complexes potassium ions. The molecule, e.g., 2,2-bis[3,4-(15-crown-5)-2-nitrophenylcarbamoxymethyl]tetradecanol-14, has at least one binding site and is provided with a fluorophore group, e.g., Rhodamine-B, at that site. The molecule is one that expands upon complexation of potassium ions, such that the intensity of fluorescence increases. The change in fluorescent intensity is a direct measure of the concentration of potassium ions. A detector employing the sensor is also provided.
docUedtek jjuni&i College THE JAUSEE ECHO XXIX ROCHESTER, MINNESOTA .FRIDAY, DECEMBER 22, 1961 NO. 6; Lw Week Date L "Brothers 4" hlertains Feb. 6 lie date for the annual Roch- ,r Junior College Snow Week [been set for February 5-10. Inning the activities of Snow U will be a convocation on Lary 23. At this convocation s club will present its queen lidate by putting on a skit. ■Wednesday, January 31, the liminary election will be held. ■queen candidates will be nar- fed down to three. On Febru- [2, the final election will be to determine the queen and ■two attendants. jhe announcement and crown- lof the queen and attendants [be on February 6 at a condition. Also, at this time, the letball players will be intro- pd, and the cheerleaders will I the students in a pep fest. (the evening of February 6, J Brothers Four will present a lour concert in Central Audi- lum. Student tickets and guest fcs will be sold for this pro- ,(Cont. on page 9, col. 5) M. Prow Wins Potlatch With Potato Landslide ...
Karlstetter, Marcus und Lippe, Elena und Walczak, Yana und Moehle, Christoph und Aslanidis, Alexander und Mirza, Myriam und Langmann, Thomas (2011) Curcumin is a potent modulator of microglial gene expression and migration. Journal of Neuroinflammation (OA-ID: 52). Knoblach, Theresa und Grandel, Benedikt und Seiler, Jana und Nevels, Michael und Paulus, Christina (2011) Human cytomegalovirus IE1 protein elicits a type II interferon-like host cell response that depends on activated STAT1 but not interferon-y. PLoS Pathogens (OA-ID: 10). Korber, Nikolaus und Gärtner, Stefanie (2011) [Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb2Sn9 x 5NH3. Acta Crystallographica Section E (OA-ID: 27). Kreczi, Amelia und Proff, Peter und Reicheneder , Claudia und Faltermeier , Andreas (2011) Effects of hypodontia on craniofacial structures and mandibular growth pattern. Head & Face Medicine (OA-ID: 60). Kreuzer, Peter und Landgrebe, Michael und Schecklmann, Martin und Timm, Pöppl und Vielsmeier, Veronika und Hajak, ...
Physiologic concentration in amniotic fluid (AF) of several metabolites has not been established with certainty. In this study, we initially assayed purines, pyrimidines, and amino compounds in 1,257 AF withdrawn between the 15th and the 20th week of gestation from actually normal pregnancies (normal gestations, normal offspring). Results allowed to determine physiologic reference intervals for 45 compounds. In these AF, not all purines and pyrimidines were detectable and uric acid (238.35 +/- A 76.31 mu mol/l) had the highest concentration. All amino compounds were measurable, with alanine having the highest concentration (401.10 +/- A 88.47 mu mol/l). In the second part of the study, we performed a blind metabolic screening of AF to evaluate the utility of this biochemical analysis as an additional test in amniocenteses. In 1,295 additional AF from normal pregnancies, all metabolites fell within the confidence intervals determined in the first part of the study. In 24 additional AF from women ...
Hydrogen bonding underpins the properties of a vast array of systems spanning a wide variety of scientific fields. From the elegance of base pair interactions in DNA to the symmetry of extended supramolecular assemblies, hydrogen bonds play an essential role in directing intermolecular forces. Yet fundamental aspects of the hydrogen bond continue to be vigorously debated. Here we use dynamic force microscopy (DFM) to quantitatively map the tip-sample force field for naphthalene tetracarboxylic diimide molecules hydrogen-bonded in two-dimensional assemblies. A comparison of experimental images and force spectra with their simulated counterparts shows that intermolecular contrast arises from repulsive tip-sample interactions whose interpretation can be aided via an examination of charge density depletion across the molecular system. Interpreting DFM images of hydrogen-bonded systems therefore necessitates detailed consideration of the coupled tip-molecule system: analyses based on intermolecular ...
1ETH: Lipase activation by nonionic detergents. The crystal structure of the porcine lipase-colipase-tetraethylene glycol monooctyl ether complex.
Ferric pyrophosphate, an iron replacement product, is a mixed-ligand iron complex in which iron (III) is bound to pyrophosphate and citrate.
1. The action of a number of acids on four properties of gelatin (membrane potentials, osmotic pressure, swelling, and viscosity) was studied. The acids used can be divided into three groups; first, monobasic acids (HCl, HBr, HI, HNO3, acetic, propionic, and lactic acids); second, strong dibasic acids (H2SO4 and sulfosalicylic acid) which dissociate as dibasic acids in the range of pH between 4.7 and 2.5; and third, weak dibasic and tribasic acids (succinic, tartaric, citric) which dissociate as monobasic acids at pH 3.0 or below and dissociate increasingly as dibasic acids, according to their strength, with pH increasing above 3.0.. 2. If the influence of these acids on the four above mentioned properties of gelatin is plotted as ordinates over the pH of the gelatin solution or gelatin gel as abscissæ, it is found that all the acids have the same effect where the anion is monovalent; this is true for the seven monobasic acids at all pH and for the weak dibasic and tribasic acids at pH below ...
Angewandte Chemie Phosphorus Heterocycles Dibenzophosphasemibullvalene** Jens Geier, Gilles Frison, and Hansjrg Grtzmacher* Dedicated to Professor Horst Prinzbach on the occasion of his "70 + " birthday Because of their frequently unusual properties, small heterocycles are of constant interest.[1] They also remain a challenge to any synthetic chemist. Three-membered rings with phosphorus are less strained than their carbon analogues,[2] tetrahedral P4 being the most prominent example.[2c] BabarPhos (I Scheme 1), a remarkable stable polycyclic phosphir- For the synthesis of the dibenzo-1-phosphasemibullvalene (4), we adopted a method developed by Niecke et al. (Scheme 1).[8] As a precursor, we prepared the 5-bis(trimethylsilyl)phosphanyl-5H-dibenzo[a,d]cycloheptene (troppSiMe3, 2)[9] which was converted into the highly air, moisture, and temperature sensitive unsymmetrical tropp(Cl)SiMe3 compound 3. The yields of 2 and 3 are almost quantitative in both reactions. The controlled thermolysis of 3 ...
Benzo- In a random urine screening as an outpatient being treated for PTSD/alcoholism, I tested 1160 for benzodiazapenes. I do not, nor have I ever taken drugs, even avoiding prescriptions at all costs (e.g., I lost weight so as to get off blood pressure meds, which worked.) I have been refusing psyche meds, opting for an intensive vitamin regimen instead. On Dec 9, I was hospitalized for drinking heavily due to flashbacks from the PTSD, at the same hospital where I am attending the IOP program. I think (not sure) I might have had a day or two of ativan? During the detox period- Im looking into that. Is it possible for that much to still be in my system a month later? My liver functions were returning to close to normal upon discharge from inpatient Dec 15th. I should also mention that this also happened about 6 months ago after a hospitalization for the same problem. I know it sounds unusual to say I have a drinking problem sometimes, but I swear I do not take drugs and have not been on ...
Several new synthetic agents show high affinity for binding adenine derivatives. The structures feature complementary hydrogen bonds that cause the molecular chelation of the purine nucleus. The high lipophilicity of the new agents permits the transport of adenosine and deoxyadenosine across organic liquid membranes. The use of synthetic receptors for small biological targets may have application in drug delivery. ...
We study the effect of membrane viscosity in the dynamics of liquid membranes{possibly with free or internal boundaries{ driven by conservative forces (curvature elasticity and line tension) and dragged by the bulk dissipation ...
The enantiomeric excess of 3.10b and 3.1 Og, has been determined from H-NMR measurements (Varian VXR 300 MHz) in the presence of the chiral europium tris-(3-(trifluormethylhydroxymethylene)-d-camphorate) (Eu(tfc)3) shift reagent. To a solution of 100 mg of Diels-Alder adduct in 0.7 ml of CDQj, 10-25 1 portions of a solution of 30 mg of Eu(tfc) j in 250 1 of CDClj were added and the H-NMR spectrum was recorded. For the enantiomers of endo-3.10g, the signals of one of the vinyl protons ( = 5.82 ppm in the absence of shift reagent) were baseline separated after addition of 65 1 (0.2 eq.) of the solution of the shift reagent. For 3.10b the sirglet of the phenyl protons at 7.15 ppm (in the absence of shift reagent) was monitored. After addition of 125 1 (0.5 eq.) of the solution of the shift reagent, the enantiomeric excess was determined after integration of the signal of the minor enantiomer (7.06 ppm, s, 4H) and of half of the sigrrificanfly shifted and splitted signal of the major enantiomer ...
A process of making a polymeric phenazonium compound having the general formula: ##STR00001## wherein R1, R2, R4, R5, R6, R8 and R9 are the same or different, and represent hydrogen, a low alkyl or a substituted aryl, R3 starts with NH2 and is diazotized followed by polymerization, R5 and R8 may alternatively represent monomeric or polymeric phenazonium radicals, R7 is a substituted amine, RX and RY represent any combination of CH3, C2H5, ##STR00002## and hydrogen, except that RX and RY cannot both be hydrogen, A is an acid radical, and n is an integer from 2 to 100, preferably from 2 to 20 is described. The polymeric phenazonium compound is usable in as an additive in a metal plating bath. The method includes the steps of: a) dissolving an effective amount of an amino compound in a formic acid solution; b) adding a nitrite salt to diazotize the amino compound; and c) adding sulfamic acid to neutralize any excess nitrous acid that may be formed in step b), whereby a polymeric phenazonium ...
Process for the preparation of aromatic amines which additionally still contain C-C multiple bonds, characterized in that aromatic nitro compounds which still contain C-C multiple bonds are hydrogenated in the presence of cobalt sulphides as catalysts, at 20 to 140 C and at 5 to 150 bars hydrogen pressure.
J. C. Ball, L. G. Puckett, and L. G. Bachas, "Covalent Immobilization of b-Galactosidase onto a Gold-Coated Magnetoelastic Transducer via a Self-Assembled Monolayer: Toward a Magnetoelastic Biosensor", Anal. Chem., 75, 6932-6937 (2003).. R. D. Johnson, I. H. A. Badr, T. Wedge, M. Diaz, M. F. Hawthorne, and L. G. Bachas, "Electronic Effects on the Selectivity of Mercuracarborand Ionophores in Ion-Selective Electrodes and Membrane Formulations for Their Use in High Protein Concentration Environments", Electroanalysis, 15, 1244-1250 (2003).. V. G. Gavalas, J. Wang, and L. G. Bachas, "Membranes for the Development of Biosensors", Membrane Science and Technology Series, 8, 379-392 (2003).. R. B. Iyer, V. Pavlov, I. Katakis, and L. G. Bachas, "Amperometric Sensing at High Temperature with a Wired Thermostable Glucose-6-phosphate Dehydrogenase from Aquifex aeolicus", Anal. Chem., 75, 3898-3901 (2003).. R. D. Johnson and L. G. Bachas, "Ionophore-Based Ion-Selective Potentiometric and Optical Sensors", ...
1.FIX BLOOD IMPRESSION: Immerse in Methanol - 1 hour - or - Immerse in 5-Sulfosalicylic acid. 2.WORKING SOLUTION APPLICATION Squeeze bottle application of dye for 2 minutes. - or - Tray immersion of item into dye for 2 minutes. 3.RINSE SOLUTIONS Squeegee bottle used to apply rinse solution for 1 minute. - or - Tray immersion containing rinse, rock tray gently for 1 minute ...
Different types of crowns and locations require different preparation, bonding and cementation techniques. This is why Dr. Koeppel has a vast array of cementation and bonding agents, to fit each case specifically.. Loose Crowns - Sometimes crowns become loose or fall off due to the bonding process, materials used, or fit or using expired materials. Matching the proper cement to the bonding agent is critical, and keeping the area clean from saliva, blood, and water during the bonding process is imperative, it is technique sensitive. Over-preparation or under-preparation may also be the culprit. If this is the problem, then re-cementing the crown will not fix the problem. Crowns that have been on for long periods of time can become loose due to decay growing underneath the crown. A little decay is mistakenly left under the crown during preparation or an ill-fitting crown can leak, where bacteria can work itself in. Some of the older cements wash, causing a space between the crown and tooth where ...
The introduction [1] of a reliable liquid membrane ion-selective micropipette (ISM) for H+has opened up an important new window onto ion and metabolic homeostasis in brain tissue. Formerly, glass...
A tooth must usually be reduced in size to accommodate a crown. A cast is made of the existing tooth and an impression is made. The impression is sent to a special lab, which manufactures a custom-designed crown. In some cases, a temporary crown is applied until the permanent crown is ready. Permanent crowns are cemented in place ...
Crown Removers Sale - price range within $10 for tip morrel crown remover, tip morrel crown remover and tip morrel crown remover.
I had a crown on #18 done which was so high I could not close my mouth. After several adjustmentsAdjustment disorder I was told it could not be adjusted anymore. I was in excrutiating pain for 3 weeks, then had the opposing tooth and crown adjusted several more times to make it fit into my mouth and relieve the biting pain I was having. I feel now that the crown fits in my mouth but the tooth next to it is hitting very hard ...
Define crown: a reward of victory or mark of honor; especially : the title representing the championship in a sport - crown in a sentence
Crown Point Cabinetry Corp in Claremont is ready to help. Make your home even more uniquely you with expert help from the skilled carpenters at Crown Point Cabinetry Corp.Think your home could use some fixing-up? Just call up Crown Point Cabinetry Corp, your friendly neighborhood service.
Crown lengthening adjusts the gum and bone level to expose more of the tooth so it can be restored. Call 410-709-3663 for an appointment.
... gigi yang dipasang pada gigi yang belum dicabut tetapi telah rosak dan tidak dapat dibaiki atau pecah. Tetapi akar gigi mestilah masih hidup dan kuat. Crown ataupun Mahkota Gigi Tiruan diperbuat daripada Porselain dan ia lebih tahan dan mudah sebab tidak perlu ditanggalkan semasa tidur, ia disemen dengan gigi kekal…
Map of The Crown Inn, Snape: Locate Snape hotels for The Crown Inn based on popularity, price, or availability, and see TripAdvisor reviews, photos, and deals.
For over 50 years, Crown Automotive has been the leading manufacturer and distributor of replacement parts for Jeep vehicles. With over 8,000 different part num
For over 50 years, Crown Automotive has been the leading manufacturer and distributor of replacement parts for Jeep vehicles. With over 8,000 different part num
Medigo lists clinics around the world offering Crown Lengthening procedures from $ 40. Compare clinics, hospitals, reviews and prices. Book an appointment and save up to 80% on Dentistry treatment abroad.
has moved to a new address:. A CUP OF JO: Half-up braided crown Sorry for the inconvenience… Redirection provided by Blogger to WordPress Migration Service ...
Call Dr. James Willoughby with all your questions regarding the CEREC system. It allows you to get a crown in about an hour. Dr. James Willoughby is a dentis…
Dioxins and dioxin-like chemicals are predominantly produced by thermal processes such as incineration and combustion at concentrations in the range of 10-100 ng of I-TEQ/kg (I-TEQ = international toxic equivalents). In this work, a new approach for the removal of dioxins from high-temperature vapor streams using facilitated supported ionic liquid membranes (SILMs) is proposed. The use of ceramic membranes containing specific ionic liquids, with extremely low volatility, for dioxin removal from incineration sources is proposed owing to their stability at very high temperatures. Supported liquid membranes were prepared by successfully immobilizing the ionic liquids tri-C₈-C₁₀-alkylmethylammonium dicyanamide ([Aliquat][DCA]) and 1-n-octyl-3-methylimidazolium dicyanamide ([Omim][DCA]) inside the porous structure of ceramic membranes. The porous inorganic membranes tested were made of titanium oxide (TiO₂), with a nominal pore size of 30 nm, and aluminum oxide (Al₂O₃), with a nominal ...
Disclosed are epoxy resin compositions comprising at least one polyglycidyl derivative of an aminophenol having the structure ##STR1## and at least one biphenyl anhydride having the structure ##STR2## wherein m is 1 or 2; wherein A is selected from the group consisting of ##STR3## WHEREIN EACH R.sup.o is individually a monovalent radical selected from the group consisting of hydrogen, halogen, hydroxy, alkyl radical having from 1 to 5 carbon atoms, alkoxy radical having from 1 to 5 carbon atoms and ##STR4## wherein R.sup.1 is an alkyl radical having from 1 to 5 carbon atoms; and wherein each R.sup.2 is individually a monovalent radical selected from the group consisting of hydrogen, halogen, alkyl radical having from 1 to 5 carbon atoms, --NO.sub.2, --COOH --SO.sub.3 H, and --NH.sub.2. The compositions are useful in such applications as molding resins, laminates, adhesives, coatings, and the like. The disclosed epoxy resin-anhydride
By using ionic liquid as membrane liquid and tri-n-octylphosphine oxide (TOPO) as additive, hollow fiber supported liquid phase microextraction (HF-LPME) was developed for the determination of five sulfonamides in environmental water samples by high-performance liquid chromatography with ultraviolet detection The extraction solvent and the parameters affecting the extraction enrichment factor such as the type and amount of carrier, pH and volume ratio of donor phase and acceptor phase, extraction time, salt-out effect and matrix effect were optimized. Under the optimal extraction conditions (organic liquid membrane phase: [C8MIM][PF6] with 14% TOPO (w/v); donor phase: 4mL, pH 4.5 KH2PO4 with 2M Na2SO4; acceptor phase: 25microL, pH 13 NaOH; extraction time: 8 h), low detection limits (0.1-0.4microg/L, RSD,or=5%) and good linear range (1-2000ng/mL, R(2),or=0.999) were obtained for all the analytes. The presence of humic acid (0-25mg/L dissolved organic carbon) and bovine serum albumin (0-100 ...
Nominated Substances: 2-Acetylamino-4-methylphenol, N-Acetyl-m-aminophenol, 5-(4-Aminobenzamido)-2,3-cresotic acid, 2-Amino-4-chloro-5-nitrophenol, 2-Amino-4-chloro-6-nitrophenol, 2-Amino-6-chloro-4-nitrophenol, 2-Amino-4-chlorophenol, 6-Amino-4-chloro-1-phenol-2-sulfonic acid, 5-Amino-o-cresol, 2-Amino-4,6-dichlorophenol, 2-Amino-4,6-dinitrophenol, 4-Amino-4-hydroxy-3-methyl-diphenylamine, 2-Amino-4-methylphenol, 3-Amino-4-methylphenol, 2-Amino-4-(methylsulfonyl)phenol, 2-Amino-3-nitro-4-methylphenol, 2-Amino-5-nitro-4-methylphenol, 4-Amino-2-nitrophenol, 2-Amino-6-nitro-1-phenol-4-sulfonic acid, 6-Amino-4-nitro-1-phenol-2-sulfonic acid, 3-Aminophenol, p-Aminophenol, 2-Amino-1-phenol-4-sulfonic acid, 3-Amino-5-sulfosalicylic acid, 5-Amino-3-sulfosalicylic acid, 2-Amino-3,4,6-trichlorophenol, 4-(3-Carbazoylamino)phenol, 4-Chloro-2-(2,4-dinitroanilino)phenol, 5-Diethylamino-2-nitroso-4-methylphenol, 5-Diethylamino-2-nitrosophenol, 3-Diethylaminophenol, 3-Dimethylamino-4-methylphenol, ...
When filtered alkaline extracts of pulverized bacteria of several varieties are precipitated with acid in the cold, boiled with acid, and all materials thrown down by these procedures removed, there remains a small amount of an alcohol-precipitable material which no longer gives any of the ordinary chemical reactions for proteins, such as the biuret, Hopkins-Cole, Millon, and sulfosalicylic acid reactions. The only protein reaction usually given by this material is a very weak xanthoproteic reaction. Nevertheless, the material, which is, as far as we can determine at present, free from coagulable protein, is specifically precipitable by homologous antiserum and gives specific complement fixation reactions.. Such material can also be obtained from organisms like the influenza bacillus, pneumococcus, and meningococcus by extraction without preliminary grinding of the bacteria, and is present in filtrates of young and old broth cultures of the organisms.. We believe that these acid- and ...
Biological light-driven proton pumps use light to move protons across a cell membrane, creating a proton gradient. Although photochromic compounds such as spiropyrans can reversibly convert between two structures with differing pKa values, spiropyrans have not been used to generate either a light-driven proton pump or an electrical current. Here, we report an artificial light-harvesting system based on a supported liquid membrane doped with a spiropyran. Irradiating the membrane with ultraviolet light induces a ring-opening reaction, converting spiropyran to merocyanine, whereas irradiation with visible light induces the reverse reaction. When the membrane is irradiated with ultraviolet and visible light on opposite sides, H+ is taken up by merocyanine, carried through the polymeric membrane and released on the other side. We show that this system produces a light-induced proton flux, an electrical current with an efficiency of ~0.12%, an open-circuit voltage of ~210 mV and a membrane gradient of ~3.6
A method for simultaneous determination of polyamines and catecholamines in cell extracts by micellar electrokinetic capillary chromatography with UV detection at 254 nm was established at the first time. The polyamines (putrescine, spermidine and spermine) and catecholamines (dopamine, serotonin, norepinephrine and epinephrine) were extracted from PC-12 cells and were derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Different derivatization conditions such as temperature, ratio of derivatization reagents and incubation time were investigated to find the best reaction condition which gave the highest detection sensitivity for polyamines and catecholamines. The influence of running buffer and additives on the separation such as pH, sodium dodecyl sulfate (SDS) concentrations and various additives was also investigated. Separation was achieved within 20 min with good repeatability in a 100 mM boric acid buffer containing 10 mM SDS and 10 mM 18-crown-6 at a pH of 9.5. The detection limit
Biological fluids such as urine, saliva and whole blood were analyzed for contents of drugs by a new combination of desorption electrospray ionization mass spectrometry (DESI-MS) and thin liquid membrane extraction (TLME). Analytes from the sample were extracted into a thin liquid membrane of hexadecane deposited on a porous Teflon membrane, from which they were subsequently analyzed directly by DESI. The total analysis time was 15 minutes for analysis of several samples with a potential analysis time of less than a minute per sample. Thanks to the pre-concentration and sample clean-up built into the method, methadone was detected in urine in full-scan mode with an LOD of 4 ng mL(-1), while amitriptyline, nortriptyline and pethidine showed LODs of 17 ng mL(-1). Quantification was possible for several basic drugs using one common internal standard, providing relative accuracies in the range of 10-30%. A reliability test was performed on 20 samples with methadone, amitriptyline, nortriptyline and ...
A vertical soap film, freely suspended at the end of a tube, is vibrated by a sound wave that propagates in the tube. If the sound wave is a piece of music, the soap film comes alive: colours, due to the soap film iridescences, swirl, split and merge at the rate of the music (see the snapshots on figure 1 below). In this article, we analyse the rich physics behind those fascinating dynamical patterns: it combines the acoustic propagation in a tube, the light interferences, and the static and dynamic properties of soap films. The interaction between the acoustic wave and the liquid membrane results in capillary waves on the soap film, as well as non-linear effects leading to a non-oscillatory flow of liquid in the plane of the film, which induces several spectacular effects: vortices generation, diphasic dynamical patterns inside the film, and swelling of the soap film under certain conditions. Each of these effects is associated with a characteristic time scale, which interacts with the characteristic
10.1021/ja00538a026 Photoresponsive crown ethers. 2. Photocontrol of ion extraction and ion transport by a bis(crown ether) ... 85550-7 Photoresponsive crown ethers. 1. Cis-trans isomerism of azobenzene as a tool to enforce conformational changes of crown ... Preparation of a crown-ether by photocycloisomerization Jean-Pierre Desvergne and Henri Bouas-Laurent J. Chem. Soc., Chem. ... construct a crown ether already incorporating the anthracene units (an anthracenophane) and also study ion uptake vs ...
... "crown" compounds with variety of ring sizes, a number of ether oxygens and substituent groups. Shortly after crown compounds, ... Classic examples are crown ethers and porphyrins. Macrocyclic ligands exhibit particularly high affinity for metal ions. ...
Crown ethers. neutral. primarily for alkali and alkaline earth metal cations 2,2,2-cryptand. hexadentate. primarily for alkali ...
"Cation Complexation and Conductivity in Crown Ether Bearing Polyphosphazenes". Macromolecules. 29 (23): 7544-7552. Bibcode: ... H. R. Allcock; S. R. Pucher; M. L. Turner; R. J. Fitzpatrick (1992). "Poly(organophosphazenes) with Poly(alkyl ether) Side ... Other side groups, such as non-fluorinated alkoxy or oligo-alkyl ether units, yield hydrophilic or hydrophobic elastomers with ...
In 1976, less than ten years after the discovery of crown ether, Cram et al. developed a functionalized binapthyl crown ether ... The catalyst makes use the crown ether motif's ability to capture cation to bind to the ammonium ion part of the substrate and ... A notable example of catalysts that employ this mechanism is Jean-Marie Lehn's crown ether. In addition, catalysts based on ... Self-assembled molecules have an advantage over crown ether and cyclodextrin in that they can capture significant larger ...
In 1967 he published two works that are now considered classics; they describe the methods of synthesizing crown ethers (cyclic ... Charles J. Pedersen (1988). "Macrocyclic Polyethers:Dibenzo-18-Crown-6 Polyether and Dicyclohexyl-18-Crown-6 Polyether". ... was an American organic chemist best known for describing methods of synthesizing crown ethers. He shared the Nobel Prize in ...
"Complexation of caesium and rubidium cations with crown ethers in N,N-dimethylformamide". Polyhedron. 15 (21): 3897-3903. doi: ...
Crown ethers arise from dialkylations that are templated by alkali metals. Other template reactions include the Mannich and ... The alkali metal-templated syntheses of crown ether syntheses are a notable exception. Another complication is that some so- ... The phosphorus analogue of an aza crown can be prepared by a template reaction. where it is not possible to isolate the ... George W. Gokel; Donald J. Cram; Charles L. Liotta; Henry P. Harris; Fred L. Cook (1988). "18-Crown-6". Organic Syntheses. ; ...
Many synthetic ionophores are based on crown ethers, cryptands, and calixarenes. These synthetic species are often macrocyclic ...
Crown-ethers bind to polyamine complexes through their second coordination sphere. Polyammonium cations bind to the nitrogen ...
... or 1,4,7,10-tetraazacyclododecane is a macrocycle and the aza analogue of the crown ether 12-crown-4. Derivatives of ... Like crown ethers, cyclen compounds are capable of selectively binding cations. They are used as a ligand in chemistry for ...
In the research lab, crown ethers are used for this purpose. Polyethylene glycols are more commonly used in practical ... and the sodium cyanide does not dissolve well in the ether. Upon the addition of small amounts of hexadecyltributylphosphonium ...
A bodipy dye attached to a crown-ether and two pyridyl groups separated by spacers (as shown below) works according to an AND ... Excess acid locks the crown ether by protonation and again the complex is dethreaded. A full adder system based on fluorescein[ ... This process is accompanied by an increase in emission intensity at 343 nm resulting from freed crown ether. Added ... phenyldiaminocarboxylate and crown ether receptors. The processing mode operates similarly as discussed above - fluorescence is ...
... has also been the director and co-director of many Ph.D.'s •Chemistry: Biomimetic chemistry, crown ethers ... crown-ether and cryptates). After his Ph.D. (1978) he spent one year at ONERA for his military service. He was then hired by ...
In one such system one macrocycle is an electron deficient oligo Bis-bipyridinium ring and the other cycle is crown ether ... The bis-macrocycle (red) contains two phenanthroline units in a crown ether chain. The interlocking ring is self-assembled when ... An example of this approach used bis-bipyridinium salts which form strong complexes threaded through crown ether bis(para- ... phenylene)-34-crown-10. Template directed syntheses are mostly performed under kinetic control, when the macrocyclization ( ...
... such as crown ethers of different sizes. The property of these peptide-crown channels depend strongly on the identity of the ... The above diagram illustrates one example, where a crown-ether was fixed across the mouth of the ion-passing portal. This ... Jochen R. Pfeifer; Philipp Reiß; Ulrich Koert (2005). "Crown Ether-Gramicidin Hybrid Ion Channels: Dehydration-Assisted Ion ...
In contrast to crown ethers, cryptands bind the guest ions using both nitrogen and oxygen donors. This three-dimensional ... These molecules are three-dimensional analogues of crown ethers but are more selective and strong as complexes for the guest ... such as crown ethers. They are able to bind otherwise insoluble salts into organic solvents. They can also be used as phase ... Pedersen for their efforts in discovering and determining uses of cryptands and crown ethers, thus launching the now ...
Since the salt is poorly soluble in nonpolar solvents, crown ethers are typically used. The tetraethylammonium salt is also ...
"Critical evaluation of stability constants and thermodynamic functions of metal complexes of crown ethers". Pure Appl. Chem. 75 ...
Classically artificial enzymes bind substrates using receptors such as cyclodextrin, crown ethers, and calixarene. Artificial ...
Charles J. Pedersen won the 1987 Nobel Prize in Chemistry for his methods of synthesizing crown ethers. Yoichiro Nambu won the ...
In most of the cases, hydrogen bonding between the crown ethers and OH or NH/NHCO moieties are involved in the form of the ... Crown ethers are another type of monomacrocyclic polymers that are used in synthesis of polyrotaxanes. The polyrotaxanes can be ... "Synthesis and characterization of new aromatic polyamides bearing crown ethers or their dipodal counterparts in the pendant ... and crown ethers (ring) and naphthalene-1,5-di-isocyanate (stopper), which involves the threading equilibrium in the chain-ring ...
Lithium ions may be chemically removed by binding to species such as cryptands or crown ethers. Metal free carbenes have been ...
A series of polynomial heterocyclic compounds, known as crown ethers, can be synthesized with ethylene oxide. One method is the ... solution of ethylene oxide in diethyl ether. The ether normally has a water content of 1.5-2%; in absence of water, ethylene ... For comparison, in alcohols the C-O-H angle is about 110°; in ethers, the C-O-C angle is 120°. The moment of inertia about each ... Ethylene glycol ethers are part of brake fluids, detergents, solvents, lacquers and paints. Other products of ethylene oxide. ...
The ketone was converted into cyanohydrin 29 with trimethylsilyl cyanide, potassium cyanide and a crown ether. As shown in ... Protection: trimethylsilyl cyanide, potassium cyanide, and a crown ether Deprotection: tetra-n-butylammonium fluoride ... The primary alcohol was protected as a silyl ether and the secondary alcohol was activated as a triflate (11). Heating this ... Ketone 14 was converted to silyl enol ether 15 by reaction with trimethylsilyl triflate, and a modified Rubottom oxidation ...
Such salts can be isolated by the addition of macrocyclic ligands such as crown ether and cryptands. These ligands bind ...
... s also readily form complexes with crown ethers (e.g. 12-crown-4 for Li+, 15-crown-5 for Na+, 18-crown-6 for K+, ... Liquid ammonia, ether, or hydrocarbon solvents are used, the most common of which being tetrahydrofuran. The most important of ... They cause the cleavage of ethers, generating alkoxides. Unlike alkyllithium compounds, alkylsodiums and alkylpotassiums cannot ... another route is the reaction of ethers with alkyl- and aryllithiums that act as strong bases.[10]:105 In non-polar solvents, ...
The use of crown ether binding with metal or ammonium cations is ubiquitous in supramolecular chemistry. The formation of ... The breakthrough came in the 1960s with the synthesis of the crown ethers by Charles J. Pedersen. Following this work, other ... Cyclodextrins, calixarenes, cucurbiturils and crown ethers are readily synthesized in large quantities, and are therefore ...
Structures of some common crown ethers. Structures of common crown ethers: 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown ... Aza-crowns. "Aza-crowns" consist of crown ethers wherein an ether oxygen has been replaced by an amine group. A well-known ... Crown ethers are heterocyclic chemical compounds that consist of a ring containing several ether groups. The most common crown ... Crown ethers in nature. Crown ethers are not the only macrocyclic ligands that have affinity for the potassium cation. ...
Contact to Crown Ethers Exporters in India, Crown Ethers Wholesalers, Crown Ethers Distributors and Traders from India. ... Search Indian Crown Ethers Manufacturers and Suppliers Details - ...
... crown ether (15-crown-5 and 18-crown-6) salts of [TcNCl4]- and [MoOCl4]-, and a new refinement of the X-ray structure of [Cs(18 ... 1 crown ether/Cs+ sand-wich cations and isolated [TcNCl4]- anions, could be obtained from reaction of Cs+/18-crown-6 and [ ... Spectra for other crown ether salts are consistent with isolated [TcNCL4]- or [TcNCL4(OH2)]- anions, with dipolar broadening ... The structure consists of an infinite sandwich Cs+ cation/crown ether configuration and polymeric [TcNCL4]- anions, with Tc≡N ...
Crown Ethers Telephone:021-67121166, 0510-85840486, 85840487 Country/Region:china ... Lauryl Pyridinium Chloride 104-74-5 LPB ... The materials in the water soluble, slightly dissolved in ethanol, ethyl ether or ...
The new crown ethers were then used for the development of [2]rotaxane ligands and metal organic rotaxane frameworks. The ... Chapter 5, focuses on a new class of MORFs in which donor groups have been incorporated on to the crown ethers which allows for ... Chapter 6, looks at ways to combine chelating axles with coordinating crown ethers to form unique combo [2]rotaxane ligands ... Chapter 3 and 4, focuses on the synthesis of new tetrasubstituted dibenzo-24-crown-8 ethers and their inclusion into [2] ...
Crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups. The most common crown ethers ... Crown ethers are much broader than the oligomers of ethylene oxide; an important group are derived from catechol. Crown ethers ... "crown" refers to the resemblance between the structure of a crown ether bound to a cation, and a crown sitting on a persons ... and 12-crown-4 for lithium cation. The high affinity of 18-crown-6 for potassium ions contributes to its toxicity. Crown ethers ...
This chapter provides the diffusion coefficient of dicyclohexano-24-crown-8-ether in ethanol at different concentrations ... Winkelmann J. (2018) Diffusion coefficient of dicyclohexano-24-crown-8-ether in ethanol. In: Lechner M.D. (eds) Diffusion in ... This chapter provides the diffusion coefficient of dicyclohexano-24-crown-8-ether in ethanol at different concentrations ...
34 Crown 10 Ether (26ZJ20)? Graingers got your back. Price:$839.45. Easy ordering & convenient delivery. Log-in or register ...
Get Crown Ethers at Spectrum Chemical. SpectrumChemical.com carries a full line of fine chemicals, lab appliances and lab ... 15-Crown 5-Ether TCI-C0859 , 33100-27-5 , C10H20O5 , TCI America 15-Crown 5-Ether is the cyclic pentamer of ethylene oxide. It ... 4-Acetylbenzo-15-crown 5-Ether TCI-A1603 , 41757-95-3 , C16H22O6 , TCI America 4-Acetylbenzo-15-crown 5-Ether ... 4-Acetylbenzo-18-crown 6-Ether TCI-A1604 , 41855-35-0 , C18H26O7 , TCI America 4-Acetylbenzo-18-crown 6-Ether ...
Crown Ether Complexes of Alkali-Metal Chlorides from SO. [Kirsten Reuter, Stefan S Rudel, Magnus R Buchner, Florian Kraus, ...
1-Aza-15-crown 5-Ether 98.0 %, TCI America 1G Chemicals:Organic Compounds:Organic nitrogen compounds:Organonitrogen compounds: ... aza-15-crown-5,1-aza-15-crown 5-ether,1-aza-15-crown-5,1-aza-15-crown,1-aza-4,7,10,13-tetraoxacyclopentadecane. ... aza-15-crown-5,1-aza-15-crown 5-ether,1-aza-15-crown-5,1-aza-15-crown,1-aza-4,7,10,13-tetraoxacyclopentadecane. ...
The Chemistry of Ethers Crown Ethers Hydroxyl Group and Their Sulphur Analogue, Supplement E, Part 1, Volume 1. ... The Chemistry of Ethers Crown Ethers Hydroxyl Group and Their Sulphur Analogue, Supplement E, Part 1, Volume 1. Saul Patai ( ...
... nanofibers functionalized with dibenzo-18-crown-6 (DB18C6) crown ether and showed the potential of these fibers for the ... The maximum adsorption capacity of the crown ether modified nanofibers for K+ was 0.37 mmol g−1 and the nanofibers followed the ... Polyacrylonitrile (PAN)/crown ether composite nanofibers for the selective adsorption of cations S. Tas, O. Kaynan, E. Ozden- ... Adsorption of Ba2+ ions onto crown ether-modified nanofiber was examined by XPS and the results confirmed the adsorption of the ...
... crown-6)]2+ cations and different anions were obtained by equimolar reaction of the hybrid disila-crown ethers 1,2-disila[15] ... crown-5 (1), 1,2-disila[18]crown-6 (2) and 1,2-disila-benzo[18]crown-6 Silicon Chemistry: Discoveries and Advances ... crown-n)]2+ (M = Mg, Ca, Sr, Ba; n = 5, 6) and [Ba(1,2-disila-benzo[18] ... crown-6)]2+ cations and different anions were obtained by equimolar reaction of the hybrid disila-crown ethers 1,2-disila[15] ...
Functionalized Derivatives of Benzo-Crown Ethers. Part 4. Antifungal Macrocyclic Supramolecular Complexes of Transition Metal ... Poly- and mononuclear metal complexes of 2,3,11,12-bis[4-(10-aminodecylcarbonyl)]benzo-18- crown-6 (L) and Cu(II); Ni(II); Co( ... In the newly prepared complexes the crown moiety oxygen atoms of the macrocyclic host did not generally interact with metal ...
The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the ... a result of the exclusion of the crown ether from the resin phase and the formation of cation-crown complexes in the solution ... Effect of crown ethers on the ion-exchange behavior of alkaline earth metals. Toward improved ion-exchange methods for the ... The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation ...
Y. Kudo, K. Harashima, S. Katsuta, and Y. Takeda, "Solvent extraction of sodium permanganate by mono-benzo 3m-crown-m ethers (m ... Extraction of Sodium Picrate by 3m-Crown-m Ethers and Their Monobenzo Derivatives (m = 5, 6) into Benzene: Estimation of Their ... Y. Kudo, N. Horiuchi, S. Katsuta, and Y. Takeda, "Extraction of cadmium bromide and picrate by 18-crown-6 ether into various ... Y. Kudo, J. Usami, S. Katsuta, and Y. Takeda, "On the difference between ion-pair formation constants of crown ether-complex ...
Up to now,more than 200 potentiometric membrane sensors for cations and anions based on Schiffs bases and crown ethers have ... Schiffs bases andcrown ethers, which feature prominently in supramolecular chemistry, can be used assensing materials in the ... Liquid membrane sensors based on Schiffs bases and crownethers will then be discussed. ... Crown Ether Supramolecule; Potentiometric membrane; Sensor; Ion Selective Electrode; Schiffs Base; Crown Ether ...
... a type of cyclic ether consisting of a ring of carbon and oxygen atoms , with two or more... , Meaning, pronunciation, ... crown ether is in the lower 50% of commonly used words in the Collins dictionary ... a type of cyclic ether consisting of a ring of carbon and oxygen atoms, with two or more carbon atoms between each oxygen atom ...
Calculated speciation curves for (a) 3,5-dnba and (b) 4-aba in methanol. Lines between points have been added as a guide to the eye. ...
Use of crown ethers can also be made in testing e.g.... ... A brief review is given on the use of crown ethers in ... Use of crown ethers can also be made in testinge.g. lithium salts for potassium by extraction as LKpicrate, L being 18-crown-6. ... A brief review is given on the use of crown ethers in solubilizing salts of alkali and alkaline earth ions in organic polar or ... Some comments on extraction analysis of cations complexed with a crown ether. ...
The CH2 vibrational modes of crown ethers have been identified and found to be split due to their interaction with ether oxygen ... Crown Ethers at the Aqueous Solution-Air Interface: 2. Electrolyte Effects, Ethylene Oxide Hydration and Temperature Behaviour ... VSFS, SFG, interface, crown ethers, ethylene oxides, ionic liquids, fatty acids, domains. Nationell ämneskategori Fysikalisk ... The presence of even small amounts of adsorbed crown ethers at the water interface is shown to considerably perturb the water ...
... Online Crown Ethers And Phase Transfer Catalysis In ... The online Crown Ethers and Phase explains a previous t fact, and by onwards the most per- Term been by a Baul violence. It ... In online Crown Ethers; pp., service David Lowery holds Info; on fiscal minutes as local books for command and will handle list ... The online Crown Ethers and Phase Transfer Catalysis in Polymer Science can thank not or now. The d enjoys additional) EPs when ...
Solvent Extraction of Sodium Permanganate by Mono-benzo 3m-Crown-m Ethers (m = 5, 6) into 1,2-Dichloroethane and Nitrobenzene: ... by crown ethers (L) into polar. diluents. Then, NaMnO4 was extracted at 25 ?C by benzo-15-crown-5 and -18-crown-6 ethers (B15C5 ... Solvent Extraction of Sodium Permanganate by Mono-benzo 3m-Crown-m Ethers (m = 5, 6) into 1,2-Dichloroethane and Nitrobenzene: ...
  • Chapter 3 and 4, focuses on the synthesis of new tetrasubstituted dibenzo-24-crown-8 ethers and their inclusion into pseudorotaxanes and rotaxanes. (uwindsor.ca)
  • Both new stoppers that can act as ligands as well as new crown ethers with appended donors were synthesized and these components combined to create new rotaxane ligands and eventually new MORFs. (uwindsor.ca)
  • The new crown ethers were then used for the development of rotaxane ligands and metal organic rotaxane frameworks. (uwindsor.ca)
  • Chapter 5, focuses on a new class of MORFs in which donor groups have been incorporated on to the crown ethers which allows for the rotaxane ligands to link though the wheel rather than axles to propagate the coordination polymer. (uwindsor.ca)
  • Chapter 6, looks at ways to combine chelating axles with coordinating crown ethers to form unique "combo" rotaxane ligands capable of forming two independent frameworks by virtue of having coordinating groups on both components of the rotaxane. (uwindsor.ca)
  • For example, ethyl methyl ether (CH 3 OC 2 H 5 ), diphenylether (C 6 H 5 OC 6 H 5 ). (wikipedia.org)
  • For example, ethyl methyl ether (CH3OC2H5), diphenylether (C6H5OC6H5). (wikipedia.org)
  • Ethyl methyl ether , or methoxyethane , is a colorless gas at room temperature, having a boiling point of 7.6 C. Like dimethyl ether, it is fairly water soluble. (angelo.edu)
  • Dimethyl ether , or more formally, methoxymethane , is a colorless gas at room temperature, having a boiling point of -42.1 C. It is fairly water soluble, with 328 grams of the gas dissolving in 100 mL of water. (angelo.edu)
  • If the ether is part of a more complex molecule, it is described as an alkoxy substituent, so -OCH 3 would be considered a " methoxy -" group. (wikipedia.org)
  • In more complicated ethers, the ether group is named as an alkoxy substituent, in which the 'yl' ending of alkyl groups is replaced by 'oxy. (angelo.edu)
  • Publications] 築部 浩: 'Double Armed Crown Ethers and Armed Macrocycles as a New Series of Metal-Selective Reagents' Talanta. (nii.ac.jp)
  • Pedersen shared the 1987 Nobel Prize in Chemistry for the discovery of the synthetic routes to and binding properties of crown ethers. (newworldencyclopedia.org)
  • Schiff's bases andcrown ethers, which feature prominently in supramolecular chemistry, can be used assensing materials in the construction of potentiometric ion selective electrodes. (mdpi.com)
  • George, M. V. (1996) Photochemistry of squaraine dyes: excited triplet state and redox properties of crown ether squaraines The Journal of Physical Chemistry, 100 (6). (ias.ac.in)
  • Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin . (wikipedia.org)
  • The crown ethers are examples of small polyethers. (wikipedia.org)
  • The phenyl ether polymers are a class of aromatic polyethers containing aromatic cycles in their main chain: Polyphenyl ether (PPE) and Poly(p-phenylene oxide) (PPO). (wikipedia.org)
  • The type of monosaccharide on the crown ether and the substituents at the nitrogen atom of the crown-ring has a major influence on both the chemical yield and enantioselectivity. (elsevier.com)
  • Acetals (α-alkoxy ethers R-CH(-OR)-O-R) are another class of ethers with characteristic properties. (wikipedia.org)
  • Epoxides, ketals, and acetals are unrepresentative classes of ethers and are discussed in separate articles. (wikipedia.org)
  • In the IUPAC nomenclature system, ethers are named using the general formula "alkoxyalkane" , for example CH 3 -CH 2 -O-CH 3 is methoxyethane . (wikipedia.org)
  • Structurally suitable ammonium phosphates, such as the Cterminal domain of RNA polymerase II or the protein kinase G target sequence, bind to the synthetic receptors by an additional intramolecular interaction between the ammonium ion and the aza crown ether. (uni-regensburg.de)
  • The binding of the ammonium ion to the aza crown ether increases the emission intensity of the fluorophore. (uni-regensburg.de)
  • Among the catalysts, the crown ether annellated to methyl-4,6-O-benzylidene-α-D-glucopyranoside, with 3-hydroxypropyl side arm at the nitrogen atom 1f proved to be the most effective (92% ee). (elsevier.com)
  • Organic hosts, such as crown ethers, cyclodextrins (CDs), calixarenes (CXs), and spherands, or polymeric additives, such as poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) were used as the micropore-forming templates. (google.ca)
  • The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. (cnrs-orleans.fr)
  • Y. Takeda, A. Kawarabayashi, K. Endō, T. Yahata, Y. Kudo, and S. Katsuta, "Solvent extraction of alkali metal (Li-Cs) picrates with 18-crown-6 into various diluents. (hindawi.com)
  • Takeda Y. The Solvent Extraction of Uni- and Bivalent Picrates by Dibenzo-24-crown-8. (springer.com)
  • Brëwster angle microscopy shows different aggregation properties of the benzo-18-crown-6-methanofullerene (1) Langmuir monolayers on pure water compared to those on a 1 M KCl subphase. (elsevier.com)
  • This work describes the immobilization of 4-carboxybenzo-18-crown-6 (CB-18-crown-6) and 4-carboxybenzo-15-crown-5 (CB-15-crown-5) assisted by lysine on aryl diazonium salt monolayers anchored to the surface of graphite-epoxy composite electrodes (GEC), and their use for the simultaneous determination of Cd(II), Pb(II) and Cu(II) by differential pulse anodic stripping voltammetry (DPASV). (uab.cat)
  • The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. (cnrs-orleans.fr)
  • 626 Hdgberg S A, G., Cram D. J. Benzocrown amino ethers // J. Org. (ximicat.com)
  • The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed. (osti.gov)
  • Ethers can again be classified into two varieties: if the alkyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. (wikipedia.org)
  • To achieve this, phthalocyanine is functionalized to possess four 18-crown-6 moieties on the macrocycle periphery, whereas fullerene is functionalized to possess an alkyl ammonium cation of short and long chain lengths. (wichita.edu)
  • Simple ethers are named by naming the alkyl groups in alphabetical order and adding the word 'ether' to the end. (angelo.edu)
  • The results of a similar experiment with the Smith tholin are shown in Figure 4, where several of the crown ether adduct peaks are labeled with an asterisk. (nasa.gov)
  • Liquid membrane sensors based on Schiff's bases and crownethers will then be discussed. (mdpi.com)
  • Dicyclohexano-18-crown-6 as active material in PVC matrix membrane for the fabrication of cadmium selective potentiometric sensor. (alfa.com)
  • Potentiometric determination of dopamine in pharmaceutical preparations by crown ether-PVC membrane sensors. (nih.gov)
  • The structure consists of an 'infinite sandwich' Cs + cation/crown ether configuration and polymeric [TcNCL 4 ] - anions, with Tc≡N distances of 1.561(36) Å, and anti-parallel chains of ---Tc≡N---Tc≡N ---with Tc···Tc separations of 4.275(4) Å. (royalsocietypublishing.org)
  • The presence of Tc≡N infrared stretching frequencies at ca . 1074 cm -1 indicates the absence of strong electron donors coordinated to Tc in the sixth position (i. e. isolated anions), whereas the polymeric chain structure of [Cs(18-crown-6)] [TcNCL 4 ] is characterized by a Tc≡N stretching frequency of 1041 cm -1 . (royalsocietypublishing.org)
  • Ion-exchange as a mode of cation transfer into room-temperature ionic liquids containing crown ethers : implications for the "greenness" of ionic liquids as diluents in liquid-liquid extraction. (osti.gov)