Influence of molecular structure and thermodynamic conditions on the dynamics, halogen bonding, and self-assembly of halogenated monoalcohols

Abstract

The research focuses on the effects of carbon chain length, halogen atom type (Cl, Br, I), and thermodynamic conditions on the molecular dynamics and formation of supramolecular structures in halogenated monoalcohols such as 2-chloro-1-ethanol, 3-chloro-1-propanol, 2-bromo-1-ethanol, 3-bromo-1-propanol, 2-iodo-1-ethanol, and 3-iodo-1-propanol. The results showed that the carbon chain length and the type of halogen atom significantly affect the relaxation processes and the ability to organize into supramolecular aggregates. Alcohols with shorter carbon chains, such as 2-chloro-1-ethanol, 2-bromo-1-ethanol, and 2-iodo-1-ethanol, showed higher Kirkwood factor values than their longer alkyl chain counterparts, suggesting a greater abundance of H-bonded clusters and/or a greater aggregation of molecules in these structures. High-pressure dielectric data combined with molecular dynamics simulations revealed that halogen-halogen interactions contribute to enhanced local structural heterogeneity, especially in brominated systems. The results indicate a greater tendency for Br atoms to form local clusters, which promotes the formation of larger and more branched O-H···O hydrogen-bonded networks. These observations highlight the critical role of halogen type and carbon chain length in shaping molecular dynamics and driving the formation of diverse supramolecular structures.