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

Abstract

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, Hw…πT, Hw…CT and Ow…CT, in TW system, and due to these interactions, each toluene can form 5~10H-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 HW…πT is primarily responsible for the stabilization of TWna(n=1–2), while OW…HT is primarily responsible for the stabilization of TWna (n=3–10). In addition, Hw…πT, Hw…CT and Ow…CT 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 Hw…πT, Hw…CT and Ow…CT. The results displayed here have potential application prospects for the development of molecular recognition systems involving aromatic interactions.