Síntese e espectroscopia aplicada na caracterização de copmplexos de curcumina com íons metálicos

Abstract

This study investigated the structural and spectroscopic properties of metal-based complexes derived from curcumin (CurcZn, CurcPb, and CurcCa) using Raman spectroscopy, FTIR, optical absorption spectroscopy, photoluminescence, and emission ellipsometry. The results revealed significant interactions between the central oxygenated groups of curcumin and the metals, with variations observed among the complexes. Raman and FTIR analyses identified shifts in vibrational modes, particularly in the enol and C=O groups, confirming metal coordination. However, it was also observed that the complexation of the CurcCa sample did not occur satisfactorily. The optical absorption spectra showed changes in peak positions and the appearance of shoulders, indicating alterations in electron density and molecular geometry. Photoluminescence measurements highlighted subtle changes in emission maxima due to metal-induced electronic transitions. Notably, the new technique of emission ellipsometry combined with applied magnetic fields provided a final perspective on the variation of Stokes parameters as a function of the applied magnetic field. This revealed distinct magneto-optical effects for the complexes: CurcZn exhibited a change in the preferred direction of emitted polarization, while CurcPb and CurcCa showed an increase in the percentage of polarized light in their preferred direction. Thus, we emphasize the impact of metal-curcumin interactions on optical properties and the introduction of a novel technique.