"Picosecond dielectric relaxation and hydrogen-bond dynamics of Trihydric alcohols in dimethyl sulfoxide mixtures".

Abstract

We report a comparative picosecond dielectric relaxation study of trihydric alcohols (glycerol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol) in binary mixtures with dimethyl sulfoxide (DMSO). Using time-domain reflectometry (TDR) in the GHz frequency range of 10 MHz to 30 GHz, we determined ε₀, τ, geff, Bruggeman factor, and excess parameters. The relaxation dynamics showed pronounced dependence on chain length and hydroxyl arrangement: longer chain triols exhibited deviations from ideal mixing due to enhanced flexibility, whereas glycerol retained unique relaxation due to compact hydrogen-bonding networks. Excess parameters and Kirkwood factors confirmed cooperative/anti-cooperative dipolar behavior modulated by solute structure. These results fill a gap in dielectric relaxation literature on trihydric alcohols and provide insights for solvent system design in biochemical and cryoprotective applications.