Faculty Publications
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Item Colorimetric recognition of water-polluting inorganic arsenic anions using near-infrared chemosensors in organic and semi-aqueous medium(Springer Science and Business Media Deutschland GmbH, 2023) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.Highly sensitive and selective chemosensors N2R1–N2R3 for detecting water-polluting inorganic arsenic anions, arsenite, and arsenate were synthesized and characterized. The selectivity of anions was studied in the pure organic media as well as the organo-aqueous media. Receptors N2R1 and N2R3 exhibited selectivity toward arsenite ion over arsenate ion in the acetonitrile media with a Limit of Detection (LOD) of 0.119 ppm and 0.323 ppm, respectively. In 30% aq. DMSO, receptors N2R1–N2R3 displayed selectivity toward arsenite and arsenate with a better LOD of 0.044 ppm. The anion binding to the receptor achieved a spectral absorption shift toward the near-infrared region in both organic and aqueous media, making the receptors better colorimetric sensors. The cyclic voltammetric investigations, 1H–NMR titration, UV–Vis titration, and DFT experiments provided strong evidence for the initial H-bonding upon interaction with the anions and the subsequent deprotonation pathway for the detection of inorganic arsenic anions. © 2023, King Abdulaziz City for Science and Technology.Item Colorimetric chemosensors for the selective detection of arsenite over arsenate anions in aqueous medium: Application in environmental water samples and DFT studies(Elsevier B.V., 2023) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.Novel organic receptors N3R1- N3R3 were developed for the selective colorimetric recognition of arsenite ions in the organo-aqueous media. In the 50% aq. acetonitrile media and 70% aq. DMSO media, receptors N3R2 and N3R3 showed specific sensitivity and selectivity towards arsenite anions over arsenate anions. Receptor N3R1 showed discriminating recognition of arsenite in the 40% aq. DMSO medium. All three receptors formed a 1:1 complex with arsenite and stable for a pH range of 6–12. The receptors N3R2 and N3R3 achieved a detection limit of 0.008 ppm (8 ppb) and 0.0246 ppm, respectively, for arsenite. Initial hydrogen bonding on binding with the arsenite followed by the deprotonation mechanism was well supported by the UV–Vis titration, 1H- NMR titration, electrochemical studies, and the DFT studies. Colorimetric test strips were fabricated using N3R1- N3R3 for the on-site detection of arsenite anion. The receptors are also employed for sensing arsenite ions in various environmental water samples with high accuracy. © 2023 Elsevier B.V.Item Colorimetric differentiation of arsenite and arsenate anions using a bithiophene sensor with two binding sites: DFT studies and application in food and water samples(Royal Society of Chemistry, 2024) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.Chemosensor N7R1 with two acidic binding sites was synthesized, and the ability of the sensor to differentiate arsenite and arsenate in the organo-aqueous medium was evaluated using colorimetric sensing methods. N7R1 distinguished arsenite with a peacock blue color and arsenate with a pale green color in a DMSO/H2O (9 : 1, v/v) solvent mixture. The specific selectivity for arsenite was achieved in DMSO/H2O (7 : 3, v/v). The sensor demonstrated stability over a pH range of 5 to 12. The computed high binding constant of 9.3176 × 1011 M−2 and a lower detection limit of 11.48 ppb for arsenite exposed the chemosensor's higher potential for arsenite detection. The binding mechanism with a 1 : 2 binding process is confirmed using UV-Vis and 1H NMR titrations, electrochemical studies, mass spectral analysis and DFT calculations. Practical applications were demonstrated by utilizing test strips and molecular logic gates. Chemosensor N7R1 successfully detected arsenite in real water samples, as well as honey and milk samples. © 2024 The Royal Society of Chemistry.