Structural and associational aspects of isomers of anisidine and toluidine under a gigahertz electric field

The relaxation times τ1 and τ2 for rotations of the flexible parts and the whole molecules of the isomers of anisidine and toluidine (j) in benzene (i) under a 9.945 GHz electric field are predicted from the slope and intercept of a linear equation of (χ0ij-χ'ij)/χ'ij against χ''ij/χ'ij for different weight fractions wj's of solute at 35 °C. χ'ij and χ''ij are the real and imaginary parts of the high-frequency complex orientational susceptibility χ*ij and χ0ij is the low-frequency susceptibility which is real. The τ's; dimensionless parameters b's involved with τ's and linear coefficients β's of χ'ij-wj curves are used to obtain dipole moments µ1 and µ2 of the flexible parts and the whole molecules. The theoretical weighted contributions c1 and c2 due to τ1 and τ2 towards dielectric dispersions from Frohlich's equations are worked out to compare with experimental ones by graphical variations of χ'ij/χ0ij and χ''ij/χ0ij at wj→0. The estimated τ's from the ratio of the individual slopes of χ''ij and χ'ij with wj's at wj→0 are compared with those of Murthy et al (1989 Indian J. Phys. B 63 491) and reported τ's. The symmetric and characteristic relaxation times τs and τcs by symmetric and asymmetric distribution parameters γ and δ are computed to suggest the symmetric relaxation behaviour of the molecules. The measured µ1 and µ2 from double relaxation phenomena and the reported µ's signify the fact that a part of the molecule is rotating under a gigahertz electric field. The slight disagreement between the theoretical dipole moment µtheo from available bond angles and bond moments of substituent polar groups attached to the parent molecules and measured µ1 demands the inductive and mesomeric effects suffered by the substituent polar groups, in addition to structural and associational aspects of such molecules.