The Effects of Oxidation States and Spin States of Chromium Interaction with &i&Sargassum Sp&/i&.: A Spectroscopic and Density Functional Theoretical Study

摘要

The study of various oxidation states of chromium with Sargassum sp . is of particular interest since hexavalent chromium is reduced to trivalent chromium in an aqueous solution. In this study, a systematic density functional theory (DFT) calculations were performed to study the interactions of transition metal chromium ion with different oxidation states and spin states with the Sar gassum sp . decorated with carboxylate (acetate) at the wB97XD/6-311++ G(d,p) level of theory. The structures and binding energies of chromium met al - carboxylate complexes at various oxidation states and spin states in gas phase were examined. The coordination strength of Cr(VI) with the acetate ligand was predominantly the strongest compare d to the other oxidation states. Vibrational frequency analysis, for the homoleptic monomers of tris [ Cr~(III)(AC)_(3)]~(0) and [Cr~(VI)(AC)_(3)]~(3+) complexes, illustrate good harmony with the experimental and theoretical calculated frequencies. Using the time - dependent DFT (TD-DFT) at the level of CAM-B3LYP/6-311++G(d,p), the vertical excitation energies were obtained. The stabilization energies derived using the second order perturbation theory, E _(ij)~((2)), of NBO analysis confirmed the greater charge transfer for the observed trends in the metal binding. The calculated binding energies (ΔE) and interactions energies S E _( ij )~( (2) ) favor the formation of [Cr~(VI)(AC)_(3)]~(3+) complexes. The findings of this study identify efficient electronic factors as major contributors to the metal binding affinities, with promising possibilities for the design of metal-ligand complexes and sensing of the metal ions.