TITLE:
The Effects of Oxidation States and Spin States of Chromium Interaction with Sargassum Sp.: A Spectroscopic and Density Functional Theoretical Study
AUTHORS:
Mohammad Abdul Matin, Md. Aftab Ali Shaikh, Md. Anwar Hossain, Md. Alauddin, Tapas Debnath, Mohammed Abdul Aziz
KEYWORDS:
Transition Metal, Time Dependent Density Functional Theory, Binding Energy, Spectroscopy, Electronic Properties and Homoleptic Coordinated Complex
JOURNAL NAME:
Green and Sustainable Chemistry,
Vol.11 No.4,
November
17,
2021
ABSTRACT: 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 Sargassum sp. decorated with carboxylate (acetate) at the wB97XD/6-311++ G(d,p) level of theory. The structures and binding energies of chromium metal-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 compared to the other oxidation states. Vibrational frequency analysis, for the homoleptic
monomers of tris [CrIII(AC)3]0 and [CrVI(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, Eij(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 SEij(2) favor the formation of [CrVI(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.