Hydrogen-bond rearrangement and Raman spectral responses of glycerol-water clusters under continuum dielectric environments: A DFT and IRI analysis.

Abstract

The structural and vibrational responses of glycerol-water clusters are closely associated with their local hydrogen-bonding environments. In this work, glycerol-water clusters with 1:1, 1:2, and 1:3 cluster compositions were investigated using density functional theory at the B3LYP/6-311 + G(d,p) level combined with the integral equation formalism polarizable continuum model (IEFPCM). Four continuum dielectric environments with ε = 24.852, 32.613, 35.688, and 46.826 were considered while keeping the explicit glycerol-water compositions unchanged. Optimized structural parameters, simulated Raman spectra, potential-energy-distribution-assisted vibrational assignments, and interaction region indicator (IRI) visualization were jointly analyzed to characterize dielectric-environment-dependent variations in hydrogen bonding. The calculations indicate that changes in the continuum dielectric environment are accompanied by variations in H···O distances, O-H···O angular directionality, and OH stretching frequencies. With increasing hydration number, the vibrational response becomes increasingly influenced by multiple glycerol-water and water-water contacts rather than by a single geometric descriptor. These results provide molecular-level computational insight into the relationship among local hydrogen-bond geometry, electronic characteristics, and Raman response in the investigated glycerol-water cluster models.