Molecular orbital analysis, vibrational spectroscopic investigation, static and dynamic NLO responses of Ethyl 6-nitro-1H-indole-3-carboxylate

Abstract

ABSTRACTThe optimized molecular geometry, vibrational spectroscopic analysis of a new hyperpolarisable molecule Ethyl 6-nitro-1H-indole-3-carboxylate (ENHIC) in the ground state were carried out using DFT (B3LYP) and LC-DFT (CAM-B3LYP) method at 6–31 + G (d). A detailed interpretation of the experimental FT-IR and FT-Raman spectra of ENHIC is reported and compared with theoretical spectrograms. Explicit vibrational assignment of all the fundamentals is identified using the potential energy distribution (PED). Natural bond orbital (NBO) analysis is revealed the charge delocalization of the molecule. In addition, a molecular electrostatic potential map (MEP) of the title compound has been analyzed for predicting the reactive sites. The electronic absorption spectra were investigated by the TD-DFT methods. HOMO-LUMO gap and reactive descriptors were calculated on the molecule. The static and dynamic (frequency) average polarizability (α), first- and second- order hyperpolarizabilities (β and γ) have been investigated by using the CAM-B3LYP method. The IEFPCM model has been used to evaluate solvent effects on the polarizability (α), first (β) – and second (γ) – order hyperpolarizabilities. These results display significant second- and third-order molecular nonlinearity of the title compound.