Zinc-curcumin complexes: Design, synthesis, geometry optimization, and optical nonlinearity applications

This may be the first research to our knowledge that details the NLO characteristics of two zinc complexes with curcumin acting as a base ligand in solution form (viz. Zinc acetate-Curcumin (ZnAcCur) and Zinc acetate-Thiolene-Curcumin (ZnThCur)). The structural features of both complexes have been derived from various characterization techniques like UV–Vis, FT-IR, 1H NMR, 13C NMR, Elemental analysis and Mass spectrometry. The nature of ligand-to-metal interaction was validated by 1H NMR spectral studies along with DFT calculations. The result shows that the molecular system ZnAcCur is more stable with a HOMO-LUMO energy gap of 3.334 eV. The addition of an extra moiety in the form of thiolene decreased the stability and in turn the NLO properties. The computational study was extended to calculate various DFT-based descriptors. Nonlinear optical transmission was measured by a Z-scan technique with the implementation of nanosecond laser pulses at 532 nm, showed that both complexes can be prominently applied for optical limiting (OL) properties.