The determination of average, anisotropic, solute-solvent interaction strengths for biphenyl, 4-bromobiphenyl, 4-cyanobiphenyl and 4-methoxybiphenyl dissolved in the nematic solvent 4′-cyano-4-methoxybiphenyl

Abstract

Deuterium NMR spectra have been obtained from samples of biphenyl-d₁₀, 4-bromobiphenyl-d₉, 4-cyanobiphenyl-d₉ and 4-methoxybiphenyl-d₅ dissolved in the nematic solvent 4-methoxy-4′-cyanobiphenyl (1-OCB), and the data used to obtain the two principal, solute order parameters, S_zz and S_xx —S_yy . These order parameters are then used to determine the average solute-solvent interaction parameters, u ₂₀₀ and u ₂₀₂, in a simple potential of mean torque. This reveals that the changes in the biaxiality, λ= u ₂₀₂/u ₂₀₀, on going from biphenyl to 1-OCB by introducing CN and OCH₃ groups are dominated by changes in u ₂₀₀ whilst u ₂₀₂ remains essentially unchanged.