Abstract
In the present study, we use a dual approach comprising of experimental and computational techniques to report the syntheses, characterizations (H-1 NMR, C-13 NMR, FT-IR, UV-visible spectroscopy and X-ray structure determination) and theoretically evaluated the third order NLO response properties of the new organic compounds; 1-((E)-(2-methoxy-4-nitrophenylimino)methyl)naphthalen-2-ol hydrate (HL1), (E)N-(ethoxy(2,3-dichlorophenyl)methyl))-2-methoxy-4-nitrobenzenamine(L 2 ) and copper(II) complex [Cu(L-3)(py)] of (E)-N'-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide(H2L3). The HL1 and L-2 were crystallized in the triclinic system of the space group P-1 with two molecules in the unit cell, whereas complex [Cu(L-3)(py)] was crystallized in the monoclinic system in the space groups P2(1/)c with eight molecules in the unit cell. The thermal properties (DSC and TG-DTG analysis) of these compounds were also investigated. State of the art quantum computational methods are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. For HL1 , L-2 and complex [Cu(L-3)(py)], their isotropic (anisotropic) values are found to be 55.46 x 10(-24) esu (71.69 x 10(-24) esu), 44.67 x 10(-24) esu (26.92 x 10(-24) esu) and 60.73 x 10(-24) esu (69.71 x 10(-24) esu), respectively. The differences in isotropic and anisotropic values are 16.23 x 10(-24) esu, 17.75 x 10(-24) esu and 9.00 x 10(-24) esu, respectively. The NLO response properties including third-order polarizability (gamma) are calculated using density functional theory (DFT) methods. The calculated gamma amplitudes for the synthesized HL1, L-2 and complex [Cu(L-3)(py)] are found to be 801.54 x 10(-36), 77.81 x 10(-36) and 311.17 x 10(-36) esu, respectively. These gamma amplitudes of HL1, L-2 and complex [Cu(L-3)(py)] are about 44, 4 and 17 times larger than that of standard para-nitroaniline (PNA, a prototype NLO molecule), respectively, which show the potential of these compounds as efficient NLO materials. Their electronic parameters and NLO properties were also evaluated using TD-DFT calculations. The HL1, L-2 and complex [Cu(L-3)(py)] showed maximum absorptions with oscillator strengths of 0.749, 0.393 and 0.368 at 2.751 3.476 and 3.214 eV, respectively. (C) 2019 Elsevier B.V. All rights reserved.