Conformation solvents

The axial-equatorial conformational equilibria for 2-fluoro- and 2-chlorotetrahydropyran have been investigated with several MO calculations, including calculations at the MP2/6-31G level. The MP2/6-31G calculations give values of 3.47 and 2.84kcal/mol, respectively, for the energy favoring the axial conformer. Solvent effects were also explored computationally and show the usual trend of reduced stability for the axial conformation as solvent polarity increases. 

Accurate measurements of fluid viscosity are important in many industries for such diverse uses as monitoring syrup manufacture or studying polymer structures such as polymer branching, chain conformation, solvent interactions or polymer molecular weight (MW). Historically, the drop-time type glass capillaries, such as the Ubbelohde or Cannon and Fenske types, have been widely used to measure fluid viscosity. However, this traditional method is tedius and labor intensive, and lacks the desired speed and sensitivity to... 

Proton transfer is coupled to the dynamics of two nuclear mode sets with widely different timescales, viz. the proton modes themselves and the environmental protein conformational and external solvent modes. The proton is trapped at the donor fragment at the equilibrium environmental conformational/solvent configuration in the reactants state, but fluctuations in these nuclear coordinates induce a state of resonance between the proton vibrational levels in the reactants and products states. Environmental gating modes with their special status in proton transfer are parts of this process. 

Peptides containing three or more amino-acid residues have been demonstrated to be better models for protein studies than the amino-acids themselves. This is because the effect of peptide-bond formation on chemical shifts has been included, while other factors such as peptide conformation, solvent effects, ionization of terminal groups, and vicinal electrostatic and steric interactions have remained... 

The solvent in which a polymer is dissolved strongly affects its conformation. Solvent quality is a general termi-... 

A structure-activity relationship has been developed for formamides which activate allyltrichlorosilane in the allylation of benzaldehyde. In the case of secondary formamides (79), the frani-conformer trans-19) predominates, but the cis- (cis-19) is suggested to be the reactive conformation. Solvent effects are also explored. 

Cellulose derivatives /Left- or right-handed helix conformation Solvents... 

Keywords Ideal polymer chain Realistic polymer chain Chain conformations Solvent quality Quenched polyelectrolyte Annealed polyelectrolyte Pearl necklace model Persistence length... 

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