Solvent Effects on Molecular Structure, Vibrational Frequencies, and NLO Properties of N-(2,3-Dichlorophenyl)-2-Nitrobenzene–Sulfonamide: a Density Functional Theory Study

Abstract

Density functional theory (DFT) calculations have been performed to obtain optimized geometries, vibrational wavenumbers, highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energies, nonlinear optical (NLO), and thermodynamic properties as well as molecular surfaces for N-(2,3-dichlorophenyl)-2-nitrobenzene–sulfonamide in different solvents. B3LYP level gives similar results for geometric parameters and vibration frequencies in gas phase, water, and ethanol solvents. The most stable structure, which is defined by the highest energy gap between HOMO and LUMO, is obtained in gas phase (∆E = 10.7376 eV). Obtained small energy gaps between HOMO and LUMO demonstrate the high-charge mobility in the titled compound. The magnitude of first static hyperpolarizability (β) parameter increases by the decreasing HOMO–LUMO energy gap. The intensive interactions between bonding and antibonding orbitals of titled compound are responsible for movement of π-electron cloud from donor to acceptor, i.e., intramolecular charge transfer (ICT), inducing the nonlinear optical properties. So, the β parameter for title compound is found to be in the range of 5.5255–3.7187 × 10−30 esu, indicating the considerable NLO character. All of these calculations have been performed in gas phase as well as water and ethanol solvents in order to demonstrate solvent effect on molecular structure, vibration frequencies, NLO properties, etc.