Synthesis, crystal structure analysis and DFT studies of 3a,8a-Dihydroxy-2-thioxo-2,3,3a,8a-tetrahydroindeno[1,2-d]imidazol-8(1H)-one

3a,8a-Dihydroxy-2-thioxo-2,3,3a,8a-tetrahydroindeno[1,2-d]imidazol-8(1H)-one (NTU) crystal was synthesized and its structural characterization was performed by X-ray diffraction method. The spectral characterization was performed by the application of MR and FT-Raman spectroscopic techniques. In order to support the experimental results, density functional theory calculations have been carried out using B3LYP/6-31G(d,p) method. The vibrational assignment of the fundamentals was proposed on the basis of potential energy distribution (PED) calculations. The stability of the molecule due to hyper conjugative interaction and charge delocalization was studied by natural bond orbital analysis. The charge transfer properties have been explained on the basis of highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs). The small energy gap between the HOMO and LUMO is an indicator of intramolecular charge transfer which is responsible for nonlinear optical properties. The first order hyperpolarizability result confirmed the nonlinear optical activity of the molecule. Molecular electrostatic potential (MEP) analysis was performed to predict the reactive sites of the molecule. The theoretical results showed good agreement with the experimental values. (C) 2017 Elsevier B.V. All rights reserved.