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  • subfamily
  • Transient Receptor Potential cation channel, subfamily Melastatin, member 8 (TRPM8) is involved in detection of cold temperature, different noxious compounds and in execution of thermo- as well as chemo-sensitive responses at cellular levels. (peerj.com)
  • electrostatic
  • Cations are adsorbed to soil surfaces by the electrostatic interaction between their positive charge and the negative charge of the surface, but they retain a shell of water molecules and do not form direct chemical bonds with the surface. (wikipedia.org)
  • It was found that interaction energies of cation-π pairs correlate well with electrostatic potential above the π face of arenes: for eleven Na+-aromatic adducts, the variation in binding energy between the different adducts could be completely rationalized by electrostatic differences. (wikipedia.org)
  • It should be noted that electrostatic attraction is not the only component of cation-π bonding. (wikipedia.org)
  • undergoes
  • Reaction with a cyclopentadienide salt of sodium or lithium yields 7-cyclopentadienylcyclohepta-1,3,5-triene: C 7H+ 7X− + C 5H− 5Na+ → C 7H 7C 5H 5 + NaX When treated with oxidising agents such as chromic acid, the tropylium cation undergoes rearrangement into benzaldehyde: C 7H+ 7 + HCrO− 4 → C 6H 5CHO + CrO 2 + H 2O Many metal complexes of tropylium ion are known. (wikipedia.org)
  • Species
  • The 1960s saw a flurry of vinyl cation-related research, with kinetics data driving the argument for the existence of the species. (wikipedia.org)
  • Generally, vinylic halides are unreactive in solution: silver nitrate does not precipitate silver halides in the presence of vinyl halides, and this fact was historically used to dispute the existence of the vinyl cation species. (wikipedia.org)
  • Advocates of the non-classical nature of the stable 2-norbornyl cation typically depict the species using either resonance structures or a single structure with partial bonds (see Figure 2). (wikipedia.org)
  • anion
  • In most soils the cation exchange capacity is much greater than the anion exchange capacity, but the opposite can occur in highly weathered soils, such as ferralsols (oxisols). (wikipedia.org)
  • molecule
  • The cation is also the simplest triatomic molecule, since its two electrons are the only valence electrons in the system. (wikipedia.org)
  • Any intermediating solvent molecule will attenuate the effect, because the energy gained by the cation-π interaction is partially offset by the loss of solvation energy. (wikipedia.org)
  • transition state
  • The potential energy diagram of this model is characterized by a single energy minimum, where the structure of the cation corresponds to the transition state between the two conformers of the classical view. (wikipedia.org)
  • The authors note that in the rate limiting step, a large positive charge develops on the benzylic carbon, indicating that the reaction proceeds through a vinyl cation transition state. (wikipedia.org)
  • geometry
  • As expected from its sp hybridization, the vinyl cation prefers a linear geometry. (wikipedia.org)
  • Extended Hückel Theory calculations for the 2-norbornyl cation suggest that the orbital on carbon 6 could instead be sp2-hybridized, though this only affects the geometry of the geminal hydrogens. (wikipedia.org)
  • Several criteria influence the strength of the bonding: the nature of the cation, solvation effects, the nature of the π system, and the geometry of the interaction. (wikipedia.org)
  • carbon
  • Some effects of divalent cations on binding and engulfment of several metal oxides and carbon particles are described. (springer.com)
  • In 1973, G. Olah was able to directly observe the 2-norbornyl cation by low-temperature NMR and confirm the presence of a non-classical 2-norbornyl cation, allowing the field to reach some conclusions about the possibilities of 3 center - 2 electron bonds involving carbon. (wikipedia.org)
  • The vinyl cation is a carbocation with the positive charge on an alkene carbon. (wikipedia.org)
  • More generally, a vinylic cation is any disubstituted, trivalent carbon, where the carbon bearing the positive charge is part of a double bond and is sp hybridized. (wikipedia.org)
  • The vinyl cation is one of the main types of reactive intermediates involving a non-tetrahedrally coordinated carbon atom, and is necessary to explain a wide variety of observed reactivity trends. (wikipedia.org)
  • In the scheme shown, the (E)- and (Z)- vinyl triflates form after heterolytic carbon-iodine bond cleavage and subsequent trapping of the cation by triflate. (wikipedia.org)
  • Reactions
  • Observations made by Saul Winstein and others suggested that highly delocalized and symmetric intermediates were present in the reactions of various substituted norbornyl cations, evidence for non-classical ions. (wikipedia.org)
  • Vinyl cations are observed as reactive intermediates in solvolysis reactions, as well during electrophilic addition to alkynes, for example, through protonation of an alkyne by a strong acid. (wikipedia.org)
  • It wasn't until the fifteen years later that this idea was revisited, with Grob and Cseh detecting vinyl cation formation during solvolysis reactions of alpha-vinyl halides in their seminal work. (wikipedia.org)
  • Generating Vinyl Cations Vinyl cations have been observed as reactive intermediates during solvolysis reactions. (wikipedia.org)
  • Recently, vinyl cation reactive intermediates have been generated in photochemical solvolysis reactions. (wikipedia.org)
  • principle
  • Positive charges of soil minerals can retain anions by the same principle as cation exchange. (wikipedia.org)
  • The cation exchange principle was discovered by Thomas Way and John Bennet Lawes at Rothamsted Experimental Station in the 19th century. (wikipedia.org)
  • family
  • The Nucleobase:Cation Symporter-1 (NCS1) Family (TC# 2.A.39) consists of over 1000 currently sequenced proteins derived from Gram-negative and Gram-positive bacteria, archaea, fungi and plants. (wikipedia.org)
  • The Nucleobase:Cation Symporter-2 (NCS2) Family, also called the Nucleobase/Ascorbate Transporter (NAT) Family, consists of over 1000 sequenced proteins derived from gram-negative and gram-positive bacteria, archaea, fungi, plants and animals. (wikipedia.org)
  • soil
  • Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. (wikipedia.org)
  • Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmolc/kg. (wikipedia.org)
  • CEC is measured in moles of electric charge, so a cation exchange capacity of 10 cmolc/kg could hold 10 cmol of Na+ cations (with 1 unit of charge per cation) per kilogram of soil, but only 5 cmol Ca2+ (2 units of charge per cation). (wikipedia.org)
  • Cation-exchange capacity arises from various negative charges on soil particle surfaces, especially those of clay minerals and soil organic matter. (wikipedia.org)
  • The cation exchange capacity of a soil is determined by its constituent materials, which can vary greatly in their individual CEC values. (wikipedia.org)
  • Base-cation saturation ratio (BCSR) is a method of interpreting soil test results that is widely used in sustainable agriculture, supported by the National Sustainable Agriculture Information Service (ATTRA) and claimed to be successfully in use on over a million acres (4,000 km²) of farmland worldwide. (wikipedia.org)
  • In the BCSR system, soil cations are balanced according to varying ratios often stated as giving 'ideal' or 'balanced' soil. (wikipedia.org)
  • These ratios can be between individual cations, such as the calcium to magnesium ratio, or they may be expressed as a percentage saturation of the cation exchange capacity (CEC) of the soil. (wikipedia.org)
  • data
  • Evidence of the non-classical nature of the 2-norbornyl cation grew over the course of several decades, mainly through spectroscopic data gathered using methods such as nuclear magnetic resonance (NMR). (wikipedia.org)
  • While the majority of chemists believed that a three-center two-electron bond best depicted its ground state electronic structure, others argued that all data concerning the 2-norbornyl cation could be explained by depicting it as a rapidly equilibrating pair of cations. (wikipedia.org)
  • Most data on cation-π interaction is acquired in the gas phase, as the attraction is most pronounced in that case. (wikipedia.org)
  • form
  • Compared to other reactive intermediates such as radicals and carbanions, the vinyl cation long remained poorly-understood and were initially thought to be too high energy to form as reactive intermediates. (wikipedia.org)
  • The tropylium cation reacts with nucleophiles to form substituted cycloheptatrienes, for example: C 7H+ 7 + CN− → C 7H 7CN Reduction by lithium aluminum hydride yields cycloheptatriene. (wikipedia.org)
  • Exchangeable cations thus form part of the diffuse layer above the charged surface. (wikipedia.org)
  • PKD1 and 2 interact to form the non-selective cation channel in vitro, but PKD2 can form channels in the absence of any other associated protein. (wikipedia.org)
  • Structure
  • Though 1-norbornyl and 7-norbornyl cations have been studied, the most extensive studies and vigorous debates have been centered on the exact structure of the 2-norbornyl cation. (wikipedia.org)
  • Each partial bond is represented as a full bond in one of the three resonance structures or as a dashed partial bond if the cation is depicted through a single structure. (wikipedia.org)
  • However, the 2-norbornyl cation can be formed from derivatives of β-(Δ3-cyclopentenyl)-ethane, indicating that the pi-bonded resonance structure is significant. (wikipedia.org)
  • several
  • The following table shows a series of Gibbs free energy of binding between benzene and several cations in the gas phase. (wikipedia.org)
  • exchange
  • Organic matter also makes a very significant contribution to cation exchange, due to its large number of charged functional groups. (wikipedia.org)
  • Increasing the pH (i.e. decreasing the concentration of H+ cations) increases this variable charge, and therefore also increases the cation exchange capacity. (wikipedia.org)
  • shown
  • The most frequently proposed molecular orbital depiction of the 2-norbornyl cation is shown in Figure 3. (wikipedia.org)
  • Polycystin-L has been shown to be a cation (Na+, K+ and Ca2+) channel that is activated by Ca2+, while polycystin-2 has been characterized as a Ca2+-permeable cation-selective channel. (wikipedia.org)
  • Channel
  • Planer lipid bilayer electrophysiology showed that TRPP3 exhibits cation channel activities that are substantially augmented by alpha-actinin. (wikipedia.org)
  • often
  • In the chemical literature, substituted vinylic cations are often referred to as vinyl cations, and understood to refer to the broad class rather than the C2H3+ variant alone. (wikipedia.org)
  • highly
  • Transition metals have the ability to share electron density with π-systems through d-orbitals, creating bonds that are highly covalent in character and cannot be modeled as a cation-π interaction. (wikipedia.org)
  • effects
  • however, energetic trends do not track well with the ability of arenes and cations to take advantage of these effects. (wikipedia.org)
  • chemical
  • These are traditionally termed "base cations" because they are non-acidic, although they are not bases in the usual chemical sense. (wikipedia.org)