Structural and theoretical study of copper(ii) complex incorporating chalcone and 2,2′-bipyridine mixed ligands: a probable candidate for optical material

Abstract

A mixed ligand containing a Cu(II) complex, CuM [Cu(L·bpy)(NO₃)] {LH = 1-(2-hydroxyphenyl)-3-(3-methyl-2-thienyl)-2-propen-1-one, bpy = 2,2′-bipyridine}, has been synthesized and characterized using spectroscopy and X-ray crystallography. It forms an orthorhombic crystal system with space group, Pbca. The Cu(II) metal exhibits slight distortion in a square pyramidal geometry in which an oxygen atom from the nitrate occupies the central apex, and the N₂O₂ core from chalcone and bipyridine form the basal plane. The crystal structure shows C–H⋯O, C–H⋯S and π–π weak non-covalent interactions and forms a chair-like 2D supramolecular architecture which is further analysed through hirshfeld surfaces, fingerprint plots and energy frameworks. The natural bond orbital, time dependent DFT and polarizability calculations are evaluated using the B3LYP/6-31G++(d,p) basis set for C, H, N, and O, and LANL2DZ set for copper. The DFT calculated nonlinear optical (NLO) responsive properties i.e. dipole moment (μ), polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ) have promising values in gas as well as solvent phases (methanol, acetonitrile, water, DSMO). The NLO properties i.e. first and second hyperpolarizability (β, γ) of CuM in the gas phase are calculated as 20.36 × 10⁻³⁰ esu and 2775.176 × 10⁻³⁶ esu, respectively. The computed NLO properties enhance with solvent polarity. The calculated nonlinear optical properties indicate that CuM is a strong candidate for the fabrication of future optoelectronic devices.