Nickel curcumin complexes: Physico chemical studies and nonlinear optical activity

Abstract

Current work presents a unique material for nonlinear optical applications. Two Ni-complexes: Nickel-Chloride-Curcumin NiCl2(Cur).2H2O (NiClCur) and Nickel-Acetate-Curcumin Ni(C2H2O3)2·2H2O (NiAcCur) were synthesized using curcumin (Cur) as a base ligand. Various spectroscopic techniques like UV–Vis, FT-IR, 1H NMR, 13C NMR, Mass spectrometry, and Elemental analysis have been used to determine both complexes’ structural characteristics. 1H NMR study discloses the complexation between metal and ligand. Theoretical analysis of NiClCur and NiAcCur is accomplished by using Conceptual-Density-Functional-Theory (CDFT) methodology. CDFT-based descriptors such as HOMO-LUMO energy gap, dipole moment, molecular hardness, softness, electronegativity, and electrophilicity index of both species are calculated. HOMO-LUMO energy gap of NiClCur and NiAcCur are found as 2.699 eV and 2.400 eV respectively. The Ni-complexes were studied for nonlinear optics (NLO) and transmission measurements were performed using a Z-scan method with nanosecond laser pulses at 532 nm. Along with transmission measurements, the optical limiting (OL) behavior of Ni-complexes was calculated. Quantitative analysis of the two-photon absorption coefficients for NiClCur and NiAcCur was determined to be 5 × 10−11 m/W and 9 × 10−12 m/W, respectively. The normalized transmittance (NT) dropped from 100% to 60% in both NiClCur and NiAcCur. This work opens up a new insight into the field of NLO, where Cur-based metal novel complexes are implemented.