Structural, Spectroscopic, Mechanical, and Nonlinear Optical Properties of 4-Dimethylaminopyridinium Picrate Single Crystal for Optoelectronic Applications

A novel organic nonlinear optical (NLO) material, 4-dimethylaminopyridinium picrate (4DMAPP) with molecular formula (C7H11N2)(+).(C6H2N3O7)(-) has been synthesized. The single crystals have been grown from synthesized material by slow evaporation technique. The NLO behavior of the 4DMAPP has been investigated using the quantum chemical calculations with 6-311++G(d,p) basis set. The bond lengths, bond angles, and torsional angle of optimized structure of 4DMAPP are in good agreement with the X-ray diffraction experimental data. The global softness, electron affinity, global hardness, Ionization potential, electronegativity, global electrophilicity, and chemical potential have been estimated. The Meyer index is found to be 2.51 and the nature of the 4DMAPP NLO material is identified as soft. Thermodynamics and molecular parameters of 4DMAPP have been carried out with zero-point vibrational energy 186.191 and 171.908 kcal/mol using Hartree-Fock (HF) and density functional theory (DFT) methods, respectively. In optical absorption spectrum, the material 4DMAPP shows the lower cut off wavelength of 325 nm. The narrow energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) facilitates the intramolecular charge transfer (ICT) which makes the material to be NLO active.