Probing the thermodynamic properties of polyol deep eutectic solvents: Based on electrostatic potential polarization and inverse gas chromatography

Abstract

This study innovatively combines molecular electrostatic potential (ESP) analysis with inverse gas chromatography (IGC) to systematically probe the thermodynamic behavior of polyol deep eutectic solvents (DESs), offering a dual-methodology framework for green solvent design in complex industrial separations. By integrating quantum chemical polarity mapping of three DESs with temperature-dependent interaction measurements across 41 solute probes, we establish a critical correlation between functional group polarity and hydrogen-bonding capacity. The ESP analysis uniquely reveals that the interaction strength order follows: alcohols > ketones > ethers > esters > halocarbons > aromatics > alkanes, directly linking molecular polarization effects to separation selectivity. Through precise IGC determination of infinite dilution activity coefficients (303.15–343.15 K), we demonstrate thermally responsive solvent–solute interactions, where 85 % of tested systems exhibit decreasing affinity with rising temperature. Notably, the DESs achieve superior selectivity and capacity in benzene-methanol separation compared to conventional ionic liquids and existing DES benchmarks, validating their potential as sustainable alternatives. This work provides a novel paradigm for rational DES screening through coupled computational-experimental analysis, advancing the mechanistic understanding of hydrogen-bond-driven separations.