Exploring dielectric relaxation in nicotinic acid-DMSO mixtures: a combined LCR, TDR and FTIR spectroscopic approach

Abstract The electrical and dielectric properties of nicotinic acid (NIA) and dimethyl sulfoxide (DMSO) binary mixtures have been investigated by using time domain reflectometry technique (TDR) in the 10 MHz to 50 GHz range at 25 °C 20 °C & 10 °C and frequency domain technique ( LCR) in the 20 Hz to 2 MHz range at 25 °C. The dielectric parameters such as complex permittivity ( ε *( ω )), loss tangent (tan δ ), Static dielectric permittivity ( ε s ), relaxation time ( τ ) and Kirkwood correlation factor (g eff ) were obtained. Thermodynamic parameters including activation enthalpy (ΔH) and entropy (ΔS) were derived to explore molecular dynamics. Optical and volumetric properties such as refractive index (n) and excess molar volume (V E ) along with electrical properties like complex conductivity σ *( ω ) and complex electrical modulus M*( ω ) were analyzed. Hydrogen bonding interactions between NIA and DMSO molecules were confirmed through these parameters and also supported by FTIR- Spectroscopy.