Supramolecular architecture of third-order nonlinear optical ammonium picrate: Crystal growth and DFT approach

Single crystals of ammonium picrate (AP), having potential applications in optical devices, were grown from a mixed solvent system methanol-acetone (2:1, v/v) by the slow evaporation technique at constant temperature. The structure is elucidated by single crystal X-ray diffraction analysis. The molecule is associated with accommodating weak CH⋯O, NH⋯O, CH⋯N, π…π and H⋯H stacking interactions, very much responsible for the formation and strengthening of supramolecular assembly. Inter- and intramolecular hydrogen bonding interactions show supramolecular architecture in the crystal packing. Two different types of architecture, i.e., a column like packing and cluster network type of infrastructure are observed. Fingerprint analysis was used to locate and analyze the quantity of the molecular interactions. Third-order non-linear optical properties of the grown crystal were derived by employing a single beam Z-scan technique at a wavelength of 532 nm with He-Ne Laser system. Theoretical calculations were performed using density functional theory (DFT) method to derive the optimized geometry, dipole moment, polarizability, HOMO-LUMO energies at different levels, excited state energy and oscillator strength. Estimated large first—order molecular hyperpolarizality of >9.81 times of urea, suggests a charge transfer atmosphere facilitating micro level nonlinearity. Idea about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density with electrostatic potential.

Figure optionsDownload as PowerPoint slide