3rd TAGRA

This study investigates the temperature-dependent dielectric relaxation of bromobenzene in two structurally different nonpolar solvents, benzene and n-hexane, with the aim of elucidating the role of solvent structure and intermolecular interactions in the dynamics and thermodynamics of dipole reorientation. The complex dielectric permittivity, including its real (ε′) and imaginary (ε″) components, was experimentally determined in the microwave range at a wavelength of λ = 12.8 mm over the temperature interval of 193–293 K. The temperature dependence of the dielectric relaxation time (τ) was established for both binary systems, allowing the effect of the molecular environment on relaxation dynamics to be assessed. Within the framework of absolute reaction-rate theory, the activation free energy (ΔF), enthalpy (ΔH), and entropy (ΔS) of the relaxation process were determined. The results demonstrate a pronounced dependence of the relaxation dynamics on the molecular structure of the solvent. Comparison of the bromobenzene–benzene and bromobenzene–n-hexane systems reveals systematic differences in the relaxation behavior and thermodynamic activation parameters, reflecting the distinct intermolecular environments surrounding the bromobenzene molecules. The novelty of this study lies in establishing a direct relationship between solvent molecular structure, dielectric relaxation dynamics, and the thermodynamic parameters governing dipole reorientation. The analysis shows that the energy barrier and degree of molecular ordering during relaxation are determined not only by the properties of bromobenzene but also by the structural organization and intermolecular interactions of the surrounding solvent. These findings provide new insight into solvent effects on dielectric relaxation in nonpolar binary molecular systems.