Physicochemical Properties, Computational Chemistry and Molecular Interactions of 1,2-Propanediamine + Hexylene Glycol Binary System

Abstract

This study measured the density (ρ) and viscosity (η) of the binary system at pressures of 1005 hPa (Tianjin, China) over the temperature range of 298.15 K to 318.15 K, with 5 K increments, and systematically analyzed its thermophysical properties and intermolecular interactions. The excess molar volume (\({{V}}_{\text{m}}^{\text{E}}\)) was calculated based on the density data, and the most stable molar ratio of 1,2-PDA to HG was determined to be 2:3. The viscosity deviation (Δη) and thermodynamic properties were calculated based on the viscosity data, and the molecular dynamic characteristics were analyzed. Spectroscopic characterization (FTIR and ¹H NMR) and density functional theory (DFT) calculations confirmed the presence of hydrogen bonding between 1,2-PDA and HG in the form of [–OH···NH₂–]. This study fills a research gap in the thermodynamic and dynamic properties of the 1,2-PDA and HG binary system, providing new insights into intermolecular interactions in complex molecular systems and offering valuable guidance for applications in the chemical and materials fields.