Structures and spectroscopic properties of low-energy candidate structures for toluene-(H2O)n (n=1-10) clusters

In this study, the dynamic behavior, geometric structure, electron density parameters and infrared spectra for toluene(T)-water(W) systems were calculated using molecular dynamics simulation, quantum chemistry calculation and wavefunction analysis. Dynamic simulations demonstrate that there are three interaction ways, H-w...pi(T), H-w...C-T and O-w...C-T, in TW system, and due to these interactions, each toluene can form 5 similar to 10H-bonds with water molecules, indicating that the toluene are easy to form H-bonds with H2O particularly at low temperature, while high temperature is harmful for that. Analyses of the TWn(n=1-10) cluster by quantum chemistry calculations and wavefunction analysis indicate that H-W...pi(T) is primarily responsible for the stabilization of TWna (n=1-2), while O-W...H-T is primarily responsible for the stabilization of TWna (n=3-10). In addition, H-w...pi(T), H-w...C-T and O-w...C-T show the dispersion and electrostatic nature. Furthermore, the degeneracy and delocalization of free OH and donor O-H modes are changed due to the formation of H-w...pi(T), H-w...C-T and O-w...C-T. The results displayed here have potential application prospects for the development of molecular recognition systems involving aromatic interactions. (C) 2020 Elsevier B.V. All rights reserved.