Role of Biomolecules in Modifying the Structural and Optical Properties of Chromium (VI) Complexes
Rajiv Vidnyan Va Vanijya Mahavidyalaya Zari-431540; Punyashlok Ahilyadevi Holkar Solapur University-413255; Shri Muktanand College Gangapur-431109; Deogiri College Chh. Sambhajinagar-431005. (MH).
Research Article
International Journal of Scholarly Research in Chemistry and Pharmacy, 2025, 05(02), 009-018.
Article DOI: 10.56781/ijsrcp.2025.5.2.0023
Publication history:
Received 08 November 2025; revised on 15 December 2025; accepted on 17 December 2025
Abstract:
Chromium(VI) complexes exhibit intense ligand-to-metal charge transfer (LMCT) transitions and strong oxidizing behavior. Their interaction with biomolecules significantly influences their structural, optical, and kinetic characteristics. This study explores the impact of four representative biomolecules—ascorbic acid, cysteine, glycine, and catechol—on Cr(VI) complexesChromium(VI) complexes exhibit strong ligand-to-metal charge transfer (LMCT) bands and high oxidative reactivity, making their interaction with biomolecules critical for understanding chromium toxicity and detoxification pathways. In this study, the structural, optical, and kinetic transformations of Cr(VI) in the presence of four representative biomolecules—ascorbic acid, cysteine, catechol, and glycine—were systematically investigated using FTIR, UV–Visible spectroscopy, HPLC analysis, and pseudo–first order kinetics. FTIR data showed disappearance or shifting of the Cr=O bands, indicating reduction to Cr(III) or coordination-induced structural changes. UV–Vis studies revealed pronounced weakening or shifts in LMCT peaks, especially for ascorbic acid and cysteine. HPLC analysis provided strong quantitative confirmation of Cr(VI) transformation, with complete disappearance of the Cr(VI) peak at 4.5 min for ascorbic acid and nearly complete reduction with cysteine.
Catechol produced distinct new peaks corresponding to Cr(III)–catecholate complexes, while glycine showed minimal chromatographic change. Kinetic analysis demonstrated that thiol- and enediol-containing biomolecules exhibit rapid electron-transfer rates. Collectively, the results establish that biomolecules significantly modulate the structural and optical behavior of Cr(VI) through reduction, chelation, or weak interaction, with HPLC offering definitive evidence of speciation changes and complex formation.
Keywords:
Chromium(VI); Biomolecules; LMCT transitions; FTIR; UV–Vis; Reduction kinetics; Cr-biomolecule complexes; HPLC Analysis.
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