Z-scan and degenerate four wave mixing studies on newly synthesized copper complexes of curcumin

Abstract

Designing novel metal complexes with high nonlinear optical (NLO) susceptibilities is a special interest for coordination compounds. They include a wider selection of metals with a variety of ligands and oxidation states, which can result in tuneable electronic capabilities. Paramagnetic Copper (II) complexes of curcumin were synthesized using different metal precursors and keeping curcumin as the base ligand. All the complexes were characterized by elemental analysis, magnetic susceptibility, and spectroscopic methods (UV–vis, FT-IR, ESR, and mass spectrometry). Nonlinear optical transmission measurements were carried out using nanosecond laser pulses with 532 nm wavelength, via a Z-scan and Degenerate four-wave mixing (DFWM) techniques. CuAcCur, CuClCur, and CuThCur complexes provided with 1.34 × 1024, 3.61 × 1024, and 4.05 × 1024 m3/W2, proved that these complexes possess excellent NLO properties and CuThCur being best among them. The NT dropped from 100 % to 78 %, 65 %, and 75 % in CuAcCur, CuClCur, and CuThCur respectively, showing that all the complexes have great potential for optical limiting (OL) application. The Conceptual-Density-Functional-Theory (CDFT) were employed to perform the theoretical analyses of complexes. Calculations on the various CDFT-based parameters such as electronegativity, HOMO-LUMO energy gap, molecular hardness, softness, dipole moment, and electrophilicity index of both species are performed. This work introduces three copper complexes with curcumin that show an excellent NLO and OL behavior.