Cross-linkage Of Molecules Research Articles

Molecular interaction in binary mixtures of 3-Bromoanisole and methanol: A microwave dielectric relaxation spectroscopy and molecular dynamic simulation study

Complex permittivity spectra for the binary mixtures of 3-bromoanisole (3-BA) and methanol (MeOH) with varying concentrations at different temperatures (T = 293.15 to 323.15 K) were obtained over a broad microwave frequency range. The complex permittivity data were fitted to different dielectric relaxation models using complex nonlinear least square fitting method. From the best fitting model dielectric relaxation parameters were extracted. Concentration dependence of the dielectric relaxation parameters were used to gain information about the molecular interaction among the constituent of the mixtures. The formation and deformation of H-bonds among the molecules of the mixture are discussed using wait-and-switch model. Temperature and concentration dependent static permittivity provided information about the alignment and cross-linkage of molecules in liquid mixtures. Molecular dynamics (MD) simulations of mixtures of 3-BA and MeOH at 293.15 K temperature have also been conducted to gain additive information regarding molecular interaction and to justify the inferences derived from the experimental microwave complex permittivity data.

Effect of esterification condensation on the Folin–Ciocalteu method for the quantitative measurement of total phenols

The Folin–Ciocalteu method is widely applied for the determination of the total phenolic contents in natural products. This method is significantly affected by the addition of sodium carbonate. The currently applied Folin–Ciocalteu methods may have been modified without any validation in the quantitative standards and the order of processes. In this study, serial experiments were performed to investigate the effect of phenolic calibrations based on the classic Folin–Ciocalteu method. Esterification condensations were observed in the assays with prior basification for gallic acid and catechin used as quantitative standards. The phenolic contents obtained in the samples differed depending on when basification occurred compared with the gallic acid calibration. The bias of the classic Folin–Ciocalteu method derived from cross-linkage of molecules was first defined in this study. The performance of the Folin–Ciocalteu method is optimised and validated again.