Complex compounds where two cyclic molecules are interlaced together as links in a chain. They have potential use in NANOTECHNOLOGY.
CIRCULAR DNA that is interlaced together as links in a chain. It is used as an assay for the activity of DNA TOPOISOMERASES. Catenated DNA is attached loop to loop in contrast to CONCATENATED DNA which is attached end to end.
A group of compounds with three aromatic rings joined in linear arrangement.
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.
Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)
A genus of facultatively anaerobic coccoid ARCHAEA, in the family SULFOLOBACEAE. Cells are highly irregular in shape and thermoacidophilic. Lithotrophic growth occurs aerobically via sulfur oxidation in some species. Distribution includes solfataric springs and fields, mudholes, and geothermically heated acidic marine environments.
A strictly autotrophic species of bacteria that oxidizes sulfur and thiosulfate to sulfuric acid. It was formerly called Thiobacillus thiooxidans.
Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity.
The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.
DNA TOPOISOMERASES that catalyze ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. These enzymes bring about relaxation of the supercoiled DNA and resolution of a knotted circular DNA duplex.
Enzymes that recombine DNA segments by a process which involves the formation of a synapse between two DNA helices, the cleavage of single strands from each DNA helix and the ligation of a DNA strand from one DNA helix to the other. The resulting DNA structure is called a Holliday junction which can be resolved by DNA REPLICATION or by HOLLIDAY JUNCTION RESOLVASES.
A bacterial DNA topoisomerase II that catalyzes ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. Topoisomerase IV binds to DNA as a heterotetramer consisting 2 parC and 2 parE subunits. Topoisomerase IV is a decatenating enzyme that resolves interlinked daughter chromosomes following DNA replication.
A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)

A reversible synthetic rotary molecular motor. (1/10)

The circumrotation of a submolecular fragment in either direction in a synthetic molecular structure is described. The movement of a small ring around a larger one occurs through positional displacements arising from biased Brownian motion that are kinetically captured and then directionally released. The sense of rotation is governed solely by the order in which a series of orthogonal chemical transformations is performed. The minimalist nature of the [2]catenane flashing ratchet design permits certain mechanistic comparisons with the Smoluchowski-Feynman ratchet and pawl. Even when no work has to be done against an opposing force and no net energy is used to power the motion, a finite conversion of energy is intrinsically required for the molecular motor to undergo directional rotation. Nondirectional rotation has no such requirement.  (+info)

Chemical peristalsis. (2/10)

Molecules that emulate in part the remarkable capabilities of protein motors were recently chemically synthesized. A promising approach is based on physically interlocked macromolecular complexes such as rotaxanes and catenanes. Using the latter, Leigh et al. [Leigh, D. A., Wong, J. K. Y., Dehez, F. & Zerbetto, F. (2003) Nature 424, 174-179] constructed a molecular rotor in which two small rings are induced by pulses of light to move unidirectionally around a third, larger ring. The mechanism is similar to that by which a peristaltic pump operates. Unlike macroscopic peristalsis, however, in which a traveling wave forces material through a series of one-way valves, the chemical peristaltic mechanism does not directly cause the small rings to move but only alters the energetics, with the motion itself arising by thermal activation over energy barriers. Engines operating by this mechanism are "Brownian" motors. Here we describe a minimal two-state mechanism for a catenane-based molecular motor. Although fluctuations caused by equilibrium processes cannot drive directed motion, nonequilibrium fluctuations, whether generated externally or by a far-from-equilibrium chemical reaction, can drive rotation even against an external torque. We discuss a possible architecture for input and output of information and energy between the motor and its environment and give a simple expression for the maximum thermodynamic efficiency. The proposed Brownian motor mechanism is consistent with the high efficiency observed by Yasuda et al. [Yasuda, Y., Noji, H., Kinoshita, K. & Yoshida, M. (1998) Cell 93, 1117-1124] for the F(1)-ATP synthase operating as an ATP-powered molecular rotor.  (+info)

Amplification of acetylcholine-binding catenanes from dynamic combinatorial libraries. (3/10)

Directed chemical synthesis can produce a vast range of molecular structures, but the intended product must be known at the outset. In contrast, evolution in nature can lead to efficient receptors and catalysts whose structures defy prediction. To access such unpredictable structures, we prepared dynamic combinatorial libraries in which reversibly binding building blocks assemble around a receptor target. We selected for an acetylcholine receptor by adding the neurotransmitter to solutions of dipeptide hydrazones [proline-phenylalanine or proline-(cyclohexyl)alanine], which reversibly combine through hydrazone linkages. At thermodynamic equilibrium, the dominant receptor structure was an elaborate [2]-catenane consisting of two interlocked macrocyclic trimers. This complex receptor with a 100 nM affinity for acetylcholine could be isolated on a preparative scale in 67% yield.  (+info)

Bovine mitochondrial peroxiredoxin III forms a two-ring catenane. (4/10)

A crystal structure is reported for the C168S mutant of a typical 2-Cys peroxiredoxin III (Prx III) from bovine mitochondria at a resolution of 3.3 A. Prx III is present as a two-ring catenane comprising two interlocking dodecameric toroids that are assembled from basic dimeric units. Each ring has an external diameter of 150 A and encompasses a central cavity that is 70 A in width. The concatenated dodecamers are inclined at an angle of 55 degrees, which provides a large contact surface between the rings. Dimer-dimer contacts involved in toroid formation are hydrophobic in nature, whereas the 12 areas of contact between interlocked rings arise from polar interactions. These two major modes of subunit interaction provide important insights into possible mechanisms of catenane formation.  (+info)

Dynamic donor-acceptor [2]catenanes. (5/10)

Donor-acceptor [2]catenanes based on cyclobis(paraquat-p-phenylene) as the pi-acceptor ring have been used prominently in the construction of functional molecular devices. We report here their thermodynamically controlled synthesis from isolated pi-donor and pi-acceptor rings under the catalytic influence of tetra butylammonium iodide. The initial nucleophilic attack of iodide ion, which opens up the pi-acceptor ring, is followed by complexation to the pi-donor ring and the subsequent catenation of the pi-donor ring by the pi-acceptor ring [2]catenane. The reaction is general in scope and proceeds in high yields, without giving rise to side-products.  (+info)

A bistable poly[2]catenane forms nanosuperstructures. (6/10)

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A pseudocatenane structure formed between DNA and A cyclic bisintercalator. (7/10)

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[2]Catenanes decorated with porphyrin and [60]fullerene groups: design, convergent synthesis, and photoinduced processes. (8/10)

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TY - JOUR. T1 - Polymeric catenanes synthesized via click chemistry and atom transfer radical coupling. AU - Bunha, Ajaykumar. AU - Cao, Peng Fei. AU - Mangadlao, Joey. AU - Shi, Fei Mo. AU - Foster, Edward. AU - Pangilinan, Katrina. AU - Advincula, Rigoberto. PY - 2015/5/1. Y1 - 2015/5/1. N2 - A novel route for the synthesis of polymeric catenanes was demonstrated by grafting an alkyne functionalized polymer onto a supramolecularly templated azide terminated ligand followed by ring closure via atom transfer radical coupling (ATRC). The polymeric catenane was characterized via GPC and AFM imaging. This journal is. AB - A novel route for the synthesis of polymeric catenanes was demonstrated by grafting an alkyne functionalized polymer onto a supramolecularly templated azide terminated ligand followed by ring closure via atom transfer radical coupling (ATRC). The polymeric catenane was characterized via GPC and AFM imaging. This journal is. UR - ...
TY - JOUR. T1 - Towards molecular scale mechano-electronic devices:. T2 - porphyrin catenanes. AU - Gunter, Maxwell J.. AU - Johnston, Martin R.. PY - 1992. Y1 - 1992. N2 - Using self-assembly strategies, catenanes consisting of zinc and free base porphyrins with hydroquinol-containing polyether straps of different lengths interlinked with a tetracationic bipyridinium cyclophane have been synthesised.. AB - Using self-assembly strategies, catenanes consisting of zinc and free base porphyrins with hydroquinol-containing polyether straps of different lengths interlinked with a tetracationic bipyridinium cyclophane have been synthesised.. UR - http://www.scopus.com/inward/record.url?scp=37049082995&partnerID=8YFLogxK. U2 - 10.1039/C39920001163. DO - 10.1039/C39920001163. M3 - Article. AN - SCOPUS:37049082995. SP - 1163. EP - 1165. JO - Journal of the Chemical Society, Chemical Communications. JF - Journal of the Chemical Society, Chemical Communications. SN - 0022-4936. IS - 17. ER - ...
A team of researchers affiliated with several institutions in Japan has developed a way to create catenanes and a molecular trefoil knot out of para-connected benzene rings. In their paper published in the journal Science, the group describes their process and possible uses of their results. Jeff Van Raden, and Ramesh Jasti with the University of Oregon, have published a Perspective piece on the work done by the team in the same journal issue. In recent years, carbon-based materials such as graphene, fullerenes and carbon nanotubes have captured the imagination of scientists-such materials have a wide range of unique physical properties that make them useful for certain applications. Graphene, for example, is a zero-gap semiconductor. Scientists have also been looking at ways in which such structures can be formed. In this new effort, the researchers have found a way to get benzene rings to form into two kinds of catenanes, and also a trefoil knot. Catenanes are a type of molecular architecture ...
TY - JOUR. T1 - Predicting knot and catenane type of products of site-specific recombination on twist knot substrates. AU - Valencia, Karin. AU - Buck, Dorothy. N1 - Copyright © 2011 Elsevier Ltd. All rights reserved.. PY - 2011/8/12. Y1 - 2011/8/12. N2 - Site-specific recombination on supercoiled circular DNA molecules can yield a variety of knots and catenanes. Twist knots are some of the most common conformations of these products, and they can act as substrates for further rounds of site-specific recombination. They are also one of the simplest families of knots and catenanes. Yet, our systematic understanding of their implication in DNA and important cellular processes such as site-specific recombination is very limited. Here, we present a topological model of site-specific recombination characterizing all possible products of this reaction on twist knot substrates, extending the previous work of Buck and Flapan. We illustrate how to use our model to examine previously uncharacterized ...
Benzylic amide catenanes are a class of synthetically-accessible interlocked molecular rings which can rotate one through the other depending on the nature of the local environment. The rings contain four phenyl units each and interlocking also affords their packing in novel, highly interacting ways that may lead to unexpected properties thus opening up the possibility of developing new materials. Third harmonic generation in benzylic amide catenane solutions was measured at a wavelength of lambda = 1064 nm, with the fundamental and the harmonic wavelengths in the region of transparency of the material. The thoroughly non resonant value of the hyperpolarisability gamma(-3 omega; omega, omega, omega) was found to be (6.5 +/- 0.7) x 10(-35) esu with a neg ligible imaginary part, in agreement with the value of (6.8 +/- 0.9)x 10(-35) esu calculated from a bond-additivity model of hyperpolarisability. The static second order hyperpolarisability predicted by a Molecular Orbital model was about a ...
The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and {[}2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen-bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB {[}2]catenane, in comparison to the acyclic XB receptor, due to the interlocked hosts unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the {[}2]catenane in competitive organicaqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared to the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy ...
The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and {[}2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen-bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB {[}2]catenane, in comparison to the acyclic XB receptor, due to the interlocked hosts unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the {[}2]catenane in competitive organicaqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared to the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy ...
Here is another molecule of the year, on a topic close to my heart, the catenane systems 1 and the trefoil knot 2 Such topology is closely inter-twinned with
The synthesis and photophysical properties of small gold nanoparticles (NPs, AuNP-[Ru-PFF]) surface functionalized by 5-substituted-1,10-phenanthroline-ligand based Ru(ii) complexes are described. Luminescence of the grafted and confined Ru(ii) complexes is totally quenched on the gold surface. Nonlinear opt
The discovery of the B-form structure of DNA by Watson and Crick led to an explosion of research on nucleic acids in the fields of biochemistry, biophysics, and genetics. Powerful techniques were developed to reveal a myriad of different structural conformations that change B-DNA as it is transcribed, replicated, and recombined and as sister chromosomes are moved into new daughter cell compartments during cell division. This article links the original discoveries of superhelical structure and molecular topology to non-B form DNA structure and contemporary biochemical and biophysical techniques. The emphasis is on the power of plasmids for studying DNA structure and function. The conditions that trigger the formation of alternative DNA structures such as left-handed Z-DNA, inter- and intra-molecular triplexes, triple-stranded DNA, and linked catenanes and hemicatenanes are explained. The DNA dynamics and topological issues are detailed for stalled replication forks and for torsional and structural
As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. ...
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Molecular Biology. STRUCTURAL MOLECULAR BIOLOGY. ...
This invention is concerned with removing metals and sulfur from oil, preferably from residual oil, by contact with a novel catalyst. Said catalyst comprises a Group VIII metal and a Group VI metal deposited within an amorphous porous glass support of controlled pore size distribution.
Diffusion ordered spectroscopy (DOSY) NMR experiments have been used to characterize a dynamic combinatorial library of helical strands and grid-type metallosupramolecular architectures. The technique allows the deconvolution of very similar chemical structures differing only by their hydrodynamic radius. Moreover, the occurrence of springlike, extension-contraction conformational motions in helical strands can be revealed as a function of the temperature. ...
Scientists at Nagoya University have succeeded in synthesizing molecular nanocarbons with knots and catenanes by using a novel method in which silicon atoms are used. The epoch-making product of this research will pave the way to the development of new nanocarbon materials with complex geometric structures.
20] Spruell, J. M.†; Coskun, A.†; Friedman, D. C.; Forgan, R. S.; Sarjeant, A. A.; Trabolsi, A.; Fahrenbach, A. C.; Barin, G.; Paxton, W. F.; Dey, S. K.; Olson, M. A.; Benítez, D.; Tkatchouk, E.; Colvin, M. T.; Carmielli, R.; Caldwell, S. T.; Rosair, G. M.; Hewage, S. G.; Duclairoir, F.; Seymour, J. L.; Slawin, A. M. Z.; Goddard III, W. A.; Wasielewski, M. R.; Cooke, G; Stoddart, J. F. Highly Stable TTF Radical Dimers in [3]Catenanes, Nature Chem., 2010, 2, 870-879. pdf ...
On the other hand, for both regular triangular and quadrilateral meshes, we present several examples of interpolatory ternary subdivision schemes with two-ring stencils such that the critical Hölder smoothness exponents of their basis functions do achieve the optimal smoothness upper bound ...
Mixed metallo-porphyrin cages were selected and amplified from dynamic combinatorial libraries (DCLs) by using appropriate templates. The cages are composed of two bisphosphine substituted zinc(II) porphyrins as ligand donors and two rhodium(III) or ruthenium(II) porphyrins as ligand acceptors, and are connected through metal-phosphorus coordination. Ru and Rh porphyrins that display a large structural diversity were employed. The templating was achieved by using 4,4-bpy, 3,3-dimethyl-4,4-bipyridine and benzo[lmn]-3,8-phenanthroline, and acts through zinc-nitrogen coordination. The absolute amount of amplification from the DCLs is strongly dependent on the combination of the Ru/Rh porphyrin and the template; cages with sterically demanding porphyrins can only form with smaller templates. In the case of tert-butyl-substituted TPP (TPP=tetraphenylporphyrin), cages are not formed at all. The formation of the cages is usually complete within 24 h at an ambient temperature; in the case of the cage ...
We have demonstrated that, in Escherichia coli, quinolone antimicrobial agents target topoisomerase IV (topo IV). The inhibition of topo IV becomes apparent only when gyrase is mutated to quinolone resistance. In such mutants, these antibiotics caused accumulation of replication catenanes, which is diagnostic of a loss of topo IV activity. Mutant forms of topo IV provided an additional 10-fold resistance to quinolones and prevented drug-induced catenane accumulation. Drug inhibition of topo IV differs from that of gyrase. (i) Wild-type topo IV is not dominant over the resistant allele. (ii) Inhibition of topo IV leads to only a slow stop in replication. (iii) Inhibition of topo IV is primarily bacteriostatic. These differences may result from topo IV acting behind the replication fork, allowing for repair of drug-induced lesions. We suggest that this and a slightly higher intrinsic resistance of topo IV make it secondary to gyrase as a quinolone target. Our results imply that the quinolone ...
The tyrosine family of recombinases produces two smaller DNA circles when acting on circular DNA harboring two recombination sites in head-to-tail orientation. If the substrate is supercoiled, these circles can be unlinked or form multiply linked catenanes. The topological complexity of the products varies strongly even for similar recombination systems. This dependence has been solved here. Our computer simulation of the synapsis showed that the bend angles, phi, created in isolated recombination sites by protein binding before assembly of the full complex, determine the product topology. To verify the validity of this theoretical finding we measured the values of phi for Cre/loxP and Flp/FRT systems. The measurement was based on cyclization of the protein-bound short DNA fragments in solution. Despite the striking similarity of the synapses for these recombinases, action of Cre on head-to-tail target sites produces mainly unlinked circles, while that of Flp yields multiply linked catenanes. In full
Ethylene cross-bridged cyclam with two acetate pendant arms, ECB-TE2A, is known to form the most kinetically stable 64Cu complexes. However, its usefulness as a bifunctional chelator is limited because of its harsh radiolabeling conditions. Herein, we report new cross-bridged cyclam chelator for the development of ultrastable 64Cu-radiolabeled bioconjugates. Propylene cross-bridged TE2A (PCB-TE2A) was successfully synthesized in an efficient way. The Cu(II) complex of PCB-TE2A exhibited much higher kinetic stability than ECB-TE2A in acid decomplexation studies, and also showed high resistance to reduction-mediated demetalation. Furthermore, the quantitative radiolabeling of PCB-TE2A with 64Cu was achieved under milder conditions compared to ECB-TE2A. Biodistribution studies strongly indicate that the 64Cu complexes of PCB-TE2A cleared out rapidly from the body with minimum decomplexation. © 2012 American Chemical Society. ...
The crystal structure of the double-stranded DNA bacteriophage HK97 mature empty capsid was determined at 3.6 angstrom resolution. The 660 angstrom diameter icosahedral particle contains 420 subunits with a new fold. The final capsid maturation step is an autocatalytic reaction that creates 420 isopeptide bonds between proteins. Each subunit is joined to two of its neighbors by ligation of the side-chain lysine 169 to asparagine 356. This generates 12 pentameric and 60 hexameric rings of covalently joined subunits that loop through each other, creating protein chainmail: topologically linked protein catenanes arranged with icosahedral symmetry. Catenanes have not been previously observed in proteins and provide a stabilization mechanism for the very thin HK97 capsid. ...
Dynamic combinatorial chemistry utilises reversible reactions to set up a dynamic library of molecules, with the library composition determined by the thermodynamic stability of each library member. Upon addition of a protein template, any library members which bind to the template are stabilised and amplified. Analysis of the library composition enables the identification of molecules which bind to the template protein. The suitability of two enzyme catalysed reactions catalysed by N-acetylneuraminic acid aldolase and subtilisin® Carlsberg was investigated for use in the synthesis of a DCL. A 173 component dynamic combinatorial library was successfully synthesised using these reactions with the resulting library screened against two protein template molecules, wheat germ agglutinin and Div1B. Several methods were investigated for the simplification of DCL analysis including the immobilisation of protein template molecules and the segregation of DCL proteins using semi-permiable membranes, ...
We design and synthesise new molecular materials, and explore how their properties relate to their molecular structures. This is molecular engineering - engineering at the nano-scale. We use non-covalent self-assembly to control the behaviour of organic semiconductors and dyes, for diverse applications. Our core technique is synthesis, but we also do many other types of experiments, from biological testing to solid-state physics. We explore the conformational, electronic and recognition properties of our compounds using a wide range of spectroscopic and analytical techniques, and we collaborate closely with physicists, physical chemists and biologists.. Projects are being pursued in the following areas: (1) Light-harvesting π-conjugated porphyrin arrays; (2) Photoactive molecules as tools for biomedical research; (3) Single-molecule electronic devices; (4) Polyyne rotaxanes and catenanes; (5) Understanding cooperatively and molecular recognition; (6) Luminescent insulated molecular ...
Catenanes, rotaxanes and knots are characterized by their mechanically interlocked architectures. These molecules are of interest to scientists due to their rare and curious presence in nature, difficulty to synthesize, and potential for use in molecular machines. While synthetic organic chemists have made great strides in creating these entangled structures, very few examples exist in protein-based biological macromolecules. Lasso peptides are one of the only naturally occurring examples of a [1]rotaxane structure in protein space. These molecules are ribosomally synthesized and post-translationally modified into their unique threaded fold. Many of these peptides harbor native biological activity and impressive topological stability, and their potential use as a bioactive scaffold has motivated research in the field. While many approaches to engineer these molecules focus on genetic transformation, we show that altering the chemistry/shape of these structures in vitro offers a new route for ...
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A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to modulate DNA topology and maintain chromosomes in an underwound state. Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Also able to catalyze the interconversion of other topological isomers of dsDNA rings, including catenanes and knotted rings. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner.
DNA gyrase subunit A; A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to modulate DNA topology and maintain chromosomes in an underwound state. Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Also able to catalyze the interconversion of other topological isomers of dsDNA rings, including catenanes and knotted rings. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner (923 aa ...
The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI). Hence, data of the category substances can be used to cover this endpoint. Yakabe et al (1994) found that for loadings of 400 - 10,000 mg/L, and under heterogeneous conditions, oligomeric MDI had a half-life of ca. 20h at 25°C when the disappearance rate was fitted to a zero-order kinetic model. However the rate constant increased approximately linearly with the nominal concentration of oligomeric MDI for all constituents. For the two-ring constituents the rate constant was found to be 0.5h-1 (i.e. half-life = 1.4 hour) for a loading of 1000 mg/L oligomeric MDI. The findings in the Yakabe et al (1994) study concur with the generally accepted chemistry of hydrolysis of an isocyanate whereby the initially produced carbamate decarboxylates to amine which then reacts very readily with more isocyanate to produce a urea. For a diisocyanate of low solubility such as MDI, the reaction system is usually ...
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TY - JOUR. T1 - Complete Double Epoxidation of Divinylbenzene Using Mn(porphyrin)-Based Porous Organic Polymers. AU - Zhang, Kainan. AU - Farha, Omar K.. AU - Hupp, Joseph T.. AU - Nguyen, Son Binh T.. PY - 2015/8/7. Y1 - 2015/8/7. N2 - A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields via the Yamamoto-Ullmann couplings of tetrabromo spirobifluorene with several brominated porphyrin monomers. After isolation and demetalation, the metal-free PPOP can be postsynthetically metalated to form a MnIII-PPOP that is catalytically active toward the selective double-epoxidation of divinylbenzene to divinylbenzene dioxide. (Chemical Equation Presented).. AB - A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields via the Yamamoto-Ullmann couplings of tetrabromo spirobifluorene with several brominated porphyrin monomers. After isolation and demetalation, the metal-free PPOP can be postsynthetically metalated to form a ...
A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to modulate DNA topology and maintain chromosomes in an underwound state. Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Also able to catalyze the interconversion of other topological isomers of dsDNA rings, including catenanes and knotted rings. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner.
NTCDI is redox-active, forming stable radical anions near -1.10 V vs. Fc/Fc+.[5] Its ability to accept electrons reflects the presence of an extended conjugated ring system and the electron withdrawing groups (carbonyl centers). NDI is used in supramolecular chemistry owing to its tendency to form charge-transfer complexes with crown ethers, e.g., to give rotaxanes and catenanes. As another consequence of their planar structure and electron-acceptor properties, NDIs intercalate into DNA. It is also suitable for fabrication of soft electronic devices.[6]. ...
Mitochondria are involved either directly or indirectly in oncogenesis and the alteration of metabolism in cancer cells. Cancer cells contain large numbers of abnormal mitochondria and produce large amounts of reactive oxygen species (ROS). Oxidative stress is caused by an imbalance between the production of ROS and the antioxidant capacity of the cell. Several cancer therapies, such as chemotherapeutic drugs and radiation, disrupt mitochondrial homeostasis and release cytochrome c, leading to apoptosome formation, which activates the intrinsic pathway. This is modulated by the extent of mitochondrial oxidative stress. The peroxiredoxin (Prx) system is a cellular defense system against oxidative stress, and mitochondria in cancer cells are known to contain high levels of Prx III. Here, we review accumulating evidence suggesting that mitochondrial oxidative stress is involved in cancer, and discuss the role of the mitochondrial Prx III antioxidant system as a potential target for cancer therapy. We hope
Get this from a library! Synthesis and reactivity of donor-acceptor substituted aminocyclopropanes and aminocyclobutanes. [Florian de Nanteuil] -- This thesis presents a general approach to accessing nitrogen-substituted hetero- and carbocycles. In short, the annulation reactions developed in the thesis make it possible to access ...
DNA gyrase subunit A; A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to modulate DNA topology and maintain chromosomes in an underwound state. Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Also able to catalyze the interconversion of other topological isomers of dsDNA rings, including catenanes and knotted rings. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner (897 aa ...
Aromatic donor-acceptor interactions have been utilized by the Iverson group in the development of abiotic molecules, called aedamers, that achieve new folding motifs, intermolecular association in heteroduplexes, and new material properties. These molecules exploit the interaction between the electron-rich 1,5-dialkoxynapthalene (DAN) and electron-deficient 1,4,5,8-naphthalenetetracarboxylic diimide (NDI) units in a face-centered stacking geometry in aqueous solution. This dissertation describes the use of DAN-NDI interactions in the realm of peptides and proteins to expand the scope for applications of this interaction. This work specifically focuses on three areas of aromatic donor-acceptor interactions: achieving protein behavior with abiotic molecules, introducing the interaction into natural peptides, and utilizing the interaction in the intermolecular association of an abiotic molecule and a natural peptide. Chapter 2 refines the model of aggregation of an amphiphilic aedamer, which forms ...
58. X.-H. Xu, X.-G. Fu, L.-Z. Wu, B. Chen, L.-P. Zhang, C.-H. Tung, H.-F. Ji, K. S. Schanze, R.-Q. Zhang, Intramolecular Triplet Energy Transfer in Donor-Acceptor Molecules Linked by Flexible-Rigid Block Bridge , Chem. Eur. J., 2006, 12, 5238-5245. (PDF file ...
ID LACDN_1_PE6 STANDARD; PRT; 823 AA. AC LACDN_1_PE6; E4SUM1; DT 00-JAN-0000 (Rel. 1, Created) DT 00-JAN-0000 (Rel. 2, Last sequence update) DT 00-JAN-0000 (Rel. 3, Last annotation update) DE SubName: Full=DNA gyrase subunit A; (LACDN_1.PE6). GN OrderedLocusNames=LDBND_0006; OS LACTOBACILLUS DELBRUECKII SUBSP. BULGARICUS ND02. OC Bacteria; Firmicutes; Lactobacillales; Lactobacillaceae; Lactobacillus. OX NCBI_TaxID=767455; RN [0] RP -.; RG -.; RL -.; CC -!- SEQ. DATA ORIGIN: Translated from the HOGENOM CDS LACDN_1.PE6. CC Lactobacillus delbrueckii subsp. bulgaricus ND02 chromosome, complete CC genome. CC -!- ANNOTATIONS ORIGIN:E4SUM1_LACDN CC -!- FUNCTION: DNA gyrase negatively supercoils closed circular double- CC stranded DNA in an ATP-dependent manner and also catalyzes the CC interconversion of other topological isomers of double-stranded CC DNA rings, including catenanes and knotted rings (By similarity). CC -!- CATALYTIC ACTIVITY: ATP-dependent breakage, passage and rejoining CC of ...
The relationship between autoantibody status and cancer-associated scleroderma was assessed by logistic regression. Scientific evidence and mass media: Investigating the journalistic buy flomax uk intention to represent scientific uncertainty. On-surface self-organization of a robust metal-organic cluster based on copper(I) with chloride and organosulphur ligands. Catenanes: A molecular mechanics analysis of the (C13H26)2 Structure 13-13 bactrim buy online D2. and the Chapel Hill Consensus Conference (CHCC) was updated in 2012, there are currently prednisone buy online no validated diagnostic criteria for systemic vasculitides. De novo hepatitis B virus infection from anti-HBc-positive donors in pediatric living donor liver transplantation.. Risks related to the resorption dapoxetine priligy buy of a glycine-based irrigation solution. The clinical role of somatosensory evoked potential studies: a critical appraisal. We report a new atlastin mutation causing spastic paraplegia in association with ...
The first part of this Lecture will introduce the concept of molecular recognition, overview major forces of molecular self-assembly and cover several important historical milestones of the field such as the recent Nobel Prize in Chemistry 2016. We will cover many textbook examples of self-assembled systems including molecular (crown ethers, cyclodextrine and calixarenes) as well as biological (proteins, DNA) systems and slowly go up in complexity talking about rotaxanes and catenanes as precursors for the topic of molecular machines. Following examples will present self-assembled systems of various dimensionalities: 0D (micelles, fullerenes), 1D (carbon nanotubes), 2D (self-assembled monolayers, Langmuir-Blodgett films, graphene) and 3D (block copolymers, liquid crystals). We will spend much time trying to classify and sort out non-covalent interactions (e.g. van der Waals forces) that are very important in the world of molecular self-assembly. At the end of this first part, we will look at the ...
Transformation of mechanically interlocked molecules (e.g., rotaxanes and catenanes) into nanoscale materials or devices is an important step towards their real applications. In our current work, an azobenzene-modified β-cyclodextrin (β-CD) derivative that can form a self-inclusion complex in aqueous solution was prepared. The self-included β-CD derivative was then functionalized onto a gold nanoparticle (AuNP) surface via a ligand-exchange reaction in aqueous solution, leading to the formation of AuNP-[1]rotaxane hybrids. Corresponding non-self-included β-CD derivative functionalized AuNPs were also developed in a DMF/H2O mixture solution for control experiments. These hybrids were fully characterized by UV-vis and circular dichroism spectroscopies, together with transmission electron microscopy (TEM). The competitive binding behavior of the hybrids with an adamantane dimer was investigated.
Title: Rationally Designed Donor-Acceptor Random Copolymers with OptimizedComplementary Light Absorption for Highly Efficient All-Polymer Solar Cells Author: Sang Woo Kim, Joonhyeong Choi, Thi Thu Trang Bui, Changyeon Lee,Changsoon Cho, Kwangmin Na,
Composed of alternating electron-rich and electron-deficient repeating units in a fused rigid backbone, donor-acceptor conjugated ladder polymers represent a class of promising material candidates possessing a host of intriguing properties. These polymers are challenging to synthesize because of the typically low r Emerging Investigators
1: MDNSLSVCNT QLSVQDSVTL VEGSYLSQWT PVLFVLAAPF HFLYFKRNFQ ASVVQYKFIL 61: AVFITLIGTL RISIGLRDIH DILFGEKSPD GLILSISIVL TTIIIQDESH KTQMKKKRKY 121: RFFRIFGLFC SFGISSAYII HKRTDTTVDN KWELQLIEWT TQLYCVLISV YLIESVILVL 181: KQVLGTDQSF QKGNADKDVS PEIKASYLSQ LTWSWVTPLV LHGYKHNLEQ SDLWPLTPGN 241: VSTNIIPIFE KYWEEEVEKA TRERQSQEKR KIQTTTNNVE KQIKANLLNC IIRASGPALL 301: LSAFYKLLYH FAEFAFPYIL RLLIGITKDR KEDIWKGYIL AILMFSVTIF KSVVLNLHIK 361: ETQEAGRSNW VALTAVIYKK TLRLTNAAKQ DSTVGEIINL MSVDAEKIGN CVWSLNEVWA 421: VPLLFSMAFY FLWQTLGSSV FVGLIIVLLL VPVNFVLMRK SKQLQLESMD LKDARIKKMN 481: EVLNGIKVLK MYAWEECFEK CILKIRDQEL HILAKREGIQ NWMHVIWATT PFTISLCTFG 541: AYVFMDVNNV MSAEKVFVSL SLFNILQYSL HLVPHVINYF IQTAVSLKRI QNFLNNEELD 601: TSIITRNTDS EYGITVEDGT FVWDTAMEPT LKNIRFKIPE GLLVAIVGSV GAGKSSLLSA 661: ILGEMESETA KVNIKGSIAY VAQQPWIMNT SLQQNILFGQ DLDKKKYEYI LDASALRKDL 721: EVLPGGDQTE IGEKGINLSG GQKQRVSLAR AVYQNADIYL LDDSLSAVDA HVGKHIFDKI 781: IGSNGLLKEK TRILVTHGLN FIRKVDIIIT MVDGQIGEIG SFDELTGHDG PFAGFMKTYM 841: AEELSTKDAQ ...
"Guinness World Records certificate". catenane.net. Retrieved 26 May 2020. "Nanobot (Havana Parody) - A Capella Science ft. ... catenanes and molecular knots and some of the earliest synthetic molecular motors, molecular robots and functional nanomachines ...
Rotaxanes and catenanes beyond the small molecule". Chemical Society Reviews. 48 (19): 5016-5032. doi:10.1039/C8CS00888D. ISSN ... Schill, Gottfried (1971). Catenanes, Rotaxanes, and Knots (1st ed.). Academic Press. p. 204. ISBN 9781483275666. G. A. Breault ... Olympiadane Rotaxane Catenane Molecular knot Molecular Borromean rings Browne, Wesley R.; Feringa, Ben L. (2006). "Making ... This increased strength is demonstrated by the necessity of harsher conditions to remove a metal template ion from catenanes as ...
Gibson, Harry W.; Bheda, Mukesh C.; Engen, Paul T. (1994). "Rotaxanes, catenanes, polyrotaxanes, polycatenanes and related ... Gibson, Harry W.; Bheda, Mukesh C.; Engen, Paul T. (1994). "Rotaxanes, catenanes, polyrotaxanes, polycatenanes and related ... doi:10.1016/s0040-4020(01)96671-2. Schill, Gottfried; Logemann, Enno; Littke, Walter (August 1984). "Makrocyclen, Catenane und ...
Rotaxanes and catenanes beyond the small molecule". Chemical Society Reviews. 48 (19): 5016-5032. doi:10.1039/C8CS00888D. ISSN ...
Related compounds in organic chemistry are the catenanes. See: Cahn-Ingold-Prelog priority rules The stereochemical descriptors ...
Some drug molecules are chiral, and the enantiomers have different effects on biological entities. They can be sold as one enantiomer or as a racemic mixture. Examples include thalidomide, ibuprofen, and salbutamol. Adderall is an unequal mixture of both amphetamine enantiomers. A single amphetamine dose combines the neutral sulfate salts of dextroamphetamine and amphetamine, with the dextro isomer of amphetamine saccharate and D/L-amphetamine aspartate monohydrate. The prescription analgesic tramadol is also a racemate. In some cases (e.g., ibuprofen and thalidomide), the enantiomers interconvert or racemize in vivo. This means that preparing a pure enantiomer for medication is largely pointless. However, sometimes samples containing pure enantiomers may be made and sold at a higher cost in cases where the use requires specifically one isomer (e.g., for a stereospecific reagent); compare omeprazole and esomeprazole. While often only one enantiomer of the drug may be active, there are cases in ...
These differences can be very small, as in the case of the boiling point of straight-chain alkenes, such as pent-2-ene, which is 37 °C in the cis isomer and 36 °C in the trans isomer.[4] The differences between cis and trans isomers can be larger if polar bonds are present, as in the 1,2-dichloroethenes. The cis isomer in this case has a boiling point of 60.3 °C, while the trans isomer has a boiling point of 47.5 °C.[5] In the cis isomer the two polar C-Cl bond dipole moments combine to give an overall molecular dipole, so that there are intermolecular dipole-dipole forces (or Keesom forces), which add to the London dispersion forces and raise the boiling point. In the trans isomer on the other hand, this does not occur because the two C−Cl bond moments cancel and the molecule has a net zero dipole (it does however have a non-zero quadrupole). The two isomers of butenedioic acid have such large differences in properties and reactivities that they were actually given completely different ...
These approaches have been particularly successful in preparing unpredictable Catenanes and other complex macrocycles including ... "Amplification of acetylcholine-binding catenanes from dynamic combinatorial libraries". Science. 308 (5722): 667-9. Bibcode: ...
The unlinking of catenanes is performed by type IIA topoisomerases, which were recently found to be more efficient unlinking ... positive supercoiled catenanes affects their features in respect to their corresponding enzymatic reaction catalyzed by ... Topologically linked circular molecules, aka catenanes, adopt a positive supercoiled form during the process of replication of ... Vologodskii A (September 2011). "Unlinking of supercoiled DNA catenanes by type IIA topoisomerases". Biophysical Journal. 101 ( ...
Catenane Made to Order". Angewandte Chemie International Edition in English. 28 (10): 1396-1399. doi:10.1002/anie.198913961.CS1 ...
His Nobel Prize work was done in 1983, when he was the first to synthesize a catenane, a complex of two interlocking ring- ... He has described syntheses of catenanes and molecular knots based on coordination complexes. He was elected a correspondent ... "Rotaxanes and catenanes as prototypes of molecular machines and motors". Pure and Applied Chemistry. 75 (10): 1383-93. doi: ...
In the same year, Guillaume showed how the ability of the two rings in [2]catenane to rotate alone each other enables [2] ... De Bo, Guillaume; Zhang, Min (2020). "A Catenane as a Mechanical Protecting Group". J. Am. Chem. Soc. 142 (11): 5029-5033. doi: ... CS1 maint: discouraged parameter (link) De Bo, Guillaume; Zhang, Min (2020). "A Catenane as a Mechanical Protecting Group". J. ... catenane to be used as a mechanical protecting group via the diversion of technical forces away from a mechanically active ...
1989). "A [2] Catenane Made to Order". J. Angew. Chem. Int. Ed. 28 (10): 1396-1399. doi:10.1002/anie.198913961. Luo, R; Gilson ... The major challenge for the synthesis of catenane is to interlock molecules in a controlled fashion. Stoddart and co-workers ... A notable example of applying π-π interactions in supramolecular assembly is the synthesis of catenane. ... catenane product. Noncovalent interaction Dispersion (chemistry) Cation-pi interaction Intercalation (biochemistry) ...
Levene, SD; Donahue, C; Boles, TC; Cozzarelli, NR (1995). "Analysis of the structure of dimeric DNA catenanes by electron ... when he collaborated with Nicholas Cozzarelli's group on the structure and properties of supercoiled DNA and DNA catenanes. ...
"Geometry and Physics of Catenanes Applied to the Study of DNA Replication". Biophysical Journal. 74 (6): 2815-2822. doi:10.1016 ...
Catenane Mechanically interlocked molecular architecture Molecular Borromean rings Molecular knots Polyrotaxane Bravo, José A ... Sauvage, J. P. (1999). "Transition Metal-Containing Rotaxanes and Catenanes in Motion: Toward Molecular Machines and Motors". ... Much of the research concerning rotaxanes and other mechanically interlocked molecular architectures, such as catenanes, has ...
To create catenanes, the cyclobis(paraquat-p-phenylene) can be used as a template to "thread" a crown ether with a π-donor ... A bistable catenane (a ring with two π-donor components) is already a simple example of a molecular switch. In the present ... The modifications include mechanically entrapped compounds such as catenanes and rotaxanes, molecular switches and larger ... "Cyclobis(paraquat-phenylene)-Based [2]Catenanes Prepared by Kinetically Controlled Reactions Involving Alkynes". Organic ...
1. [2]Rotaxanes and a [2]catenane made to order". Journal of the American Chemical Society. 114 (1): 193-218. doi:10.1021/ ...
The molecule is a linear pentacatenane or a [5]catenane. It was synthesized and named by Fraser Stoddart and coworkers in 1994 ... The molecule was designed without any practical use in mind, although other catenanes may have possible application to the ...
He has also synthesised catenanes and metal-containing polymers by dynamic ring opening polymerisation. Puddephatt was won ...
A polycatenane is a polymer consisting of mechanically linked catenane structures. Depending on the location of the catenane ... n]-Catenanes (for large n), which consist solely of the mechanically interlocked cyclic components, can be viewed as "optimized ...
Catenane Möbius strip Nucleoid Plasmid Ribbon theory Rolling circle replication Topoisomerase Theta type replication This ... In this particular experiment, when DNA gyrase alone were inhibited, most of the catenanes were unlinked. However, when ... catenanes' or topologically interlinked circles. The circles are not covalently linked, but cannot be separated because they ...
One on the synthesis of catenanes began with serious chemistry and gradually - imperceptibly - became less credible; it ...
... such as rotaxanes and catenanes. Illustrative, α-cyclodextrin form second-sphere coordination complex with tetrabromoaurate ...
Examples of mechanically interlocked molecular architectures include catenanes, rotaxanes, molecular knots, molecular Borromean ...
Examples of molecules for which there exist topoisomers include DNA, which can form knots, and catenanes. Each topoisomer of a ... Mechanically-interlocked molecular architectures Catenane Rotaxanes Molecular knot Molecular Borromean rings ^ New Molecular ... Topologies Beyond Catenanes and Rotaxanes Essay 2000 Theresa Chang American Chemical Society Online Article. ...
Cryptand Rotaxane Catenane Molecular knot Effective molarity Macrocyclic stereocontrol Hamilton-Miller, JM (1973). "Chemistry ...
Fujita, M.; Ogura, K (1996). "Supramolecular Self-Assembly of Macrocycles, Catenanes, and Cages through Coordination of ... Fujita, M.; Ogura, K (1996). "Supramolecular Self-Assembly of Macrocycles, Catenanes, and Cages through Coordination of ...
Catenane and Rotaxane molecules, and Molecular knot Interlock fabric, a double-knitted jersey fabric. Interlocking directorate ...
An interwoven grid complex has been used to template the synthesis of a doubly-twisted [2]catenane (otherwise known as a ... catenane and a granny knot. In 2021, the first report of a 3 × 3 interwoven grid was published. It was used to template the ... Catenane with Twisted Rings, and a Molecular Granny Knot". Angewandte Chemie International Edition. 57 (42): 13833-13837. doi: ...
... "catenane" in order to indicate how many rings are involved. Discrete catenanes up to a [7]catenane have been synthesised. ... Another family of catenanes are called pretzelanes or bridged [2]catenanes after their likeness to pretzels with a spacer ... When molecular recognition motifs exist in the finished catenane (usually those that were used to synthesize the catenane), the ... Li, J.; Nowak, P.; Fanlo-Virgos, H.; Otto, S. (2014). "Catenanes from Catenanes: Quantitative Assessment of Cooperativity in ...
A link (or catenane) is composed of two or more such curves, which can be intertwined. If the path can be laid flat without any ... In the case of simple torus links with 2m crossings (also called 2m-catenanes, or 2m-cats) for an integer m , 1, the sites are ... 2011) Predicting knot and catenane type of products of site-specific recombination on twist knot substrates. J Mol Biol 411(2): ... FtsK-dependent XerCD-dif recombination unlinks replication catenanes in a stepwise manner. Koya Shimokawa, Kai Ishihara, Ian ...
Different forms of DNA catenanes. (A) CatA catenanes composed of two fully replicated, torsionally relaxed rings that are ... C) CatA catenanes composed of two fully replicated and torsionally relaxed rings that are interlinked three times with each ... B) CatA catenanes composed of two torsionally relaxed rings that are interlinked twice and show four positive intermolecular ... The sign of catenane crossings is positive as newly replicated molecules inherit the directions of parental strands. The ...
2]Catenane 3 was obtained by self-assembly when the cavity size of the trapezoidal rings was optimised. ... Self-assembled [2]catenane in trapezoidal metallacycles with [Cp*Ir]-corners N. Liu, S. Huang, X. Liu, H. Luo and T. S. A. Hor ... 2]Catenane 3 was obtained by self-assembly when the cavity size of the trapezoidal rings was optimised. ...
Catenanes - molecules consisting of interlocked macrocyclic rings - have been prepared by templation strategies for some thirty ... and thermodynamically controlled reactions to synthesize catenanes are detailed. The class of catenanes that may be described ... Progress in the synthesis and exploitation of catenanes since the Millennium N. H. Evans and P. D. Beer, Chem. Soc. Rev., 2014 ... Catenanes - molecules consisting of interlocked macrocyclic rings - have been prepared by templation strategies for some thirty ...
Two [3]catenane molecular flasks have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, ... The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for ... catenanes. Nature Chemistry, 2 (10). pp. 870-879. ISSN 1755-4330. http://resolver.caltech.edu/CaltechAUTHORS:20101012-101217044 ...
Hydrogen-bond-mediated template synthesis of rotaxanes, catenanes, and knotanes. C. A. Schalley, T. Weilandt, J. Br üggemann, F ... The synthesis of rotaxanes, catenanes, and trefoil knotanes can only be efficiently accomplished, when a suitable template ... p,063,/p,,p,Hydrogen-bond-mediated template synthesis of rotaxanes, catenanes, and knotanes,/p, ... catenane, or knotane structure. Consequently, the variability of the structures available through these template syntheses is ...
Complex compounds where two cyclic molecules are interlaced together as links in a chain. They have potential use in NANOTECHNOLOGY.
... David A. Leigh, Robin G. Pritchard and Alexander J. Stephens, Nature Chem ... Figure 1. Starry, starry night. [A Star of David Catenane David A. Leigh, Robin G. Pritchard and Alexander J. Stephens, ... A Star of David Catenane David A. Leigh, Robin G. Pritchard and Alexander J. Stephens, Nature Chem, published online 21 Sept ... A Star of David Catenane. Nature Chem., published online 21 Sept 2014. ...
Isolation by crystallization of translational isomers of a bistable donor-acceptor [2]catenane. Author:. Wang, Cheng, Olson, ... The template-directed synthesis of a bistable donor-acceptor [2]catenane wherein both translational isomers--one in which a ...
Fingerprint Dive into the research topics of An ExBox [2]catenane. Together they form a unique fingerprint. * catenane ... The [2]catenane can act as a push-button molecular switch where the co-conformations of the [2]catenane can be controlled ... The [2]catenane can act as a push-button molecular switch where the co-conformations of the [2]catenane can be controlled ... The [2]catenane can act as a push-button molecular switch where the co-conformations of the [2]catenane can be controlled ...
Gunter, M. J., & Johnston, M. R. (1992). Towards molecular scale mechano-electronic devices: porphyrin catenanes. Journal of ... Gunter, Maxwell J. ; Johnston, Martin R. / Towards molecular scale mechano-electronic devices: porphyrin catenanes. In: Journal ... Gunter, MJ & Johnston, MR 1992, Towards molecular scale mechano-electronic devices: porphyrin catenanes, Journal of the ... Towards molecular scale mechano-electronic devices: porphyrin catenanes. / Gunter, Maxwell J.; Johnston, Martin R. ...
6. The Cube as a Sum of Linear Catenanes. Figure 6. The Linear Triple Catenanes that Link to Form the Cube. The target cube is ... The starting material for its synthesis was the linear triple catenane shown at the center of the drawing. This catenane ... However, when the cube is successfully synthesized, a linear triple catenane results. This catenane corresponds to the top, ... Next, we will describe the relationships that act as the basis for the construction of DNA knots and catenanes. Finally, we ...
Catenanes. Catenanes are compounds that are made of interlocking macrocycles. The interlocking rings are said to be ... Catenanes are named according to the number of interlocking rings. The simplest catenane, containing… ...
Catenanes are a type of molecular architecture with two or more interlocking macrocycles. And a trefoil knot, as its name ... In this new effort, the researchers have found a way to get benzene rings to form into two kinds of catenanes, and also a ... Making catenanes and a molecular trefoil knot out of para-connected benzene rings ... A team of researchers affiliated with several institutions in Japan has developed a way to create catenanes and a molecular ...
Cycloparaphenylenes and Their Catenanes: Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry ... Cycloparaphenylenes and Their Catenanes: Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry Zhang, W., Abdulkarim, ... Cycloparaphenylenes and their Catenanes - Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry.pdf (Any fulltext), ... Cycloparaphenylenes and their Catenanes - Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry.pdf ...
Knots, Catenanes Biotechnology Entrepreneur Commodity Commercial value Genetic Therapist Surgically insertable piece or " ...
フィンガープリント Polymeric catenanes synthesized via click chemistry and atom transfer radical coupling の研究トピックを掘り下げます。これらはともに一意の ... Polymeric catenanes synthesized via "click" chemistry and atom transfer radical coupling. Ajaykumar Bunha, Peng Fei Cao, Joey ... Polymeric catenanes synthesized via "click" chemistry and atom transfer radical coupling. Chemical Communications. 2015 5 1;51( ... Polymeric catenanes synthesized via "click" chemistry and atom transfer radical coupling. / Bunha
Some drug molecules are chiral, and the enantiomers have different effects on biological entities. They can be sold as one enantiomer or as a racemic mixture. Examples include thalidomide, ibuprofen, and salbutamol. Adderall is an unequal mixture of both amphetamine enantiomers. A single amphetamine dose combines the neutral sulfate salts of dextroamphetamine and amphetamine, with the dextro isomer of amphetamine saccharate and D/L-amphetamine aspartate monohydrate. The prescription analgesic tramadol is also a racemate. In some cases (e.g., ibuprofen and thalidomide), the enantiomers interconvert or racemize in vivo. This means that preparing a pure enantiomer for medication is largely pointless. However, sometimes samples containing pure enantiomers may be made and sold at a higher cost in cases where the use requires specifically one isomer (e.g., for a stereospecific reagent); compare omeprazole and esomeprazole. While often only one enantiomer of the drug may be active, there are cases in ...
These differences can be very small, as in the case of the boiling point of straight-chain alkenes, such as pent-2-ene, which is 37 °C in the cis isomer and 36 °C in the trans isomer.[4] The differences between cis and trans isomers can be larger if polar bonds are present, as in the 1,2-dichloroethenes. The cis isomer in this case has a boiling point of 60.3 °C, while the trans isomer has a boiling point of 47.5 °C.[5] In the cis isomer the two polar C-Cl bond dipole moments combine to give an overall molecular dipole, so that there are intermolecular dipole-dipole forces (or Keesom forces), which add to the London dispersion forces and raise the boiling point. In the trans isomer on the other hand, this does not occur because the two C−Cl bond moments cancel and the molecule has a net zero dipole (it does however have a non-zero quadrupole). The two isomers of butenedioic acid have such large differences in properties and reactivities that they were actually given completely different ...
Translational isomerism in a [3]catenane and a [3]rotaxane. Translational isomerism in a [3]catenane and a [3]rotaxane, (S. -H ...
... catenanes and Solomon knot. Molecular Borromean rings (BRs) are [3]catenanes topoisomers in which none of the component rings ... Beyond linear [3]catenanes, ring-in-ring complex are also a very rare structural motif, which can be considered as ... "All-in-one" strategy for metalla[3]catenanes, borromean rings and ring-in-ring complex. by Bioengineer ... Self-assembly of metalla[3]catenanes, borromean rings and ring-in-ring complex using a simple π-donor unit. https:/. /. doi. ...
Chemical consequences of mechanical bonding in catenanes and rotaxanes: isomerism, modification, catalysis and molecular ... Chemical consequences of mechanical bonding in catenanes and rotaxanes: isomerism, modification, catalysis and molecular ... Chemical consequences of mechanical bonding in catenanes and rotaxanes: isomerism, modification, catalysis and molecular ... Chemical consequences of mechanical bonding in catenanes and rotaxanes: isomerism, modification, catalysis and molecular ...
10.7 Catenanes and Rotaxanes.. 10.8 Helicates and Helical Assemblies.. 10.9 Molecular Knots. ...
Polymeric Catenanes Catenane Structures in Polymer Networks Conclusions and Perspective MULTICYCLIC POLYMERS Introduction Ring ...
Benzylic amide catenanes are a class of synthetically-accessible interlocked molecular rings which can rotate one through the ... Third harmonic generation in benzylic amide catenane solutions was measured at a wavelength of lambda = 1064 nm, with the ... UNSPECIFIED (2000) Nonlinear optical properties of benzylic amide [2] catenanes: a novel versatile photonic material. In: 5th ... Nonlinear optical properties of benzylic amide [2] catenanes: a novel versatile photonic material ...
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Synthesis of poly[n]catenanes. Stuart Rowan. University of Chicago, USA. 17.35. Cram Lehn Pedersen Prize: Engineering ... Davids research interests include the development of new strategies for interlocked molecule synthesis (catenanes, rotaxanes ...
Catenanes and Rotaxanes. Molecular Switches. The Electron Driven Molecular Shuttle Switch. The pH Driven Molecular Shuttle ... Synthesis of Rotaxanes and Catenanes. Rotaxanes and Molecular Computers. Chemical Rotors. Prodders. Flippers. Atom Shuttles. ...

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