DFT computation, Hirshfeld surfaces analysis, non-linear optical and spectroscopic investigations of a novel non-centrosymmetric organic`-inorganic hybrid material [(CH3CH2)4N]HSeO4(H2SeO4)2

The new hybrid compound, tetraethylammonium monohydrogenselenate bis selenic acid [(C2H5)(4)N]HSeO4(H2SeO4) 2 is synthesized by slow evaporation at room temperature of a solution containing (C2H5)(4)NOH and H2SeO4. It is crystallized in the monoclinic space group Cc (Z = 2), with the unit cell parameters: a = 19.705 (1) angstrom, b = 7.542 (3) angstrom, c = 19.199 (1) angstrom, beta = 115 degrees. The 3D Hirshfeld surface and 2D fingerprint plots analyses showed the predominance contribution of O-H...O bonding in the crystal structure crystal packing. The contributions importance of the different contacts in crystal packing of this compound are compared to that observed in the [(C3H7)(4)N]HSeO4(H2SeO4)(2) crystal. The solid-state C-13 NMR spectrum shows two signals corresponding to two different carbon environments in CH2 and CH3 groups. The IR and Raman spectra were recorded in the range 400-3600 cm(-1) and 50-3500 cm(-1), respectively. The observed bands are assigned and discussed based on the theoretical analyses and computational calculated frequencies. The theoretical bond lengths, angles, and frequencies computed from the optimized molecular geometry through DFT method using B3LYP function and the 6-31G(d) basis set, are discussed and compared to the experimental results, which reveals a good agreement between the observed and calculated parameters. The nonlinear optical properties of [(C2H5)(4)N]HSeO4(H2SeO4)(2) were studied using the DFT method, the calculated values of the electric dipole mu, the polarizability alpha, and the hyperpolarizability beta. The calculations showed that the selenate-based compound exhibits a non-zero b value, revealing NLO behavior which could be used in potential and functional applications including optical switching and optical disk data storage.