Growth, spectral and quantum chemical investigations on N-butyl-4-nitroaniline single crystal for nonlinear optical and optoelectronic device applications

N-butyl-4-nitroaniline (NB4N), an organic chromophore crystal, was synthesized by a slow solvent evaporation method. Single - crystal X-ray diffraction analysis was carried out to determine the cell parameter values. A UV–Vis-NIR spectral analysis was performed to investigate the band gap energy and optical quality. The direct optical band gap was found to be 4.83 eV and the lower cut-off wavelength is shown to be as low as 235 nm. Vibration frequencies were analyzed using FTIR spectral analysis. The Second Harmonic Generation (SHG) was confirmed via the Kurtz-Perry powder technique. The N-butyl-4-nitroaniline crystal was theoretically acquired using various computational tools to analyse its geometry (B3LYP/6-311++G(d,p)) and electronic properties. The quantum chemical calculations, such as HOMO-LUMO and molecular electrostatic potential, were calculated and presented for NB4N. The donor and acceptor’s interaction and stabilisation energy were analysed by Natural Bond Orbital (NBO) analyses. Quantum chemical evaluations of NLO activity have been computed and reported. The thermodynamic characteristics and hyperpolarizability of N-butyl-4-nitroaniline have been described.