Faculty Publications
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Item Hydrazinylpyridine based highly selective optical sensor for aqueous source of carbonate ions: Electrochemical and DFT studies(Elsevier B.V., 2018) Thimaradka, V.; Pangannaya, S.; Mohan, M.; Trivedi, D.R.A series of new receptors PDZ1–3 based on 2-(arylidenehydrazinyl)pyridines have been designed and synthesized for the detection of biologically and environmentally important ions. The colorimetric detection of CO32 ? using neutral organic receptor PDZ-1 has been achieved with characteristic visual colour change from yellow to green accompanied by a large redshift of 215 nm in absorption maxima. UV–Vis spectroscopic and cyclic voltammetric studies reveal the stoichiometry of binding and electrochemistry of host-guest complex formation. The binding constant was found to be 0.77 × 104 M? 2. In addition, electrochemical studies provide an insight into the stability of the complex. DFT studies performed on the PDZ-1 and PDZ-1 ? CO32 ? complex reveal the binding mechanism involved in the anion detection process. PDZ-1 is highly selective for carbonate and does not show any colorimetric response towards any other anions or cations, while PDZ-2 and PDZ-3 remain inactive in the ion detection process. The limit of detection (LOD) and limit of quantification (LOQ) of PDZ-1 for carbonate was found to be 0.11 mM and 0.36 mM respectively. Considerable binding constant and limit of detection make PDZ-1 to be used as a real time sensor for the detection of carbonate in environmental and biological samples. © 2017 Elsevier B.V.Item Design and synthesis new colorimetric receptors for naked-eye detection of biologically important fluoride and acetate anions in organic and arsenite in aqueous medium based on ICT mechanism: DFT study and test strip application(Elsevier B.V., 2020) Singh, A.; Mohan, M.; Trivedi, D.R.Novel three colorimetric anion receptors R1, R2 and R3 have been designed and synthesized via condensation reaction and characterized using IR, MS, and NMR spectroscopic techniques. Anion sensing properties were studied using colorimetric, UV–vis titration, 1H NMR titration, and Cyclic Voltammetric Studies. Comparing the UV–visible titration data of the receptors R1 and R2, R2 showed high redshift (??max) in the mixed competitive solution (DMSO: H2O, 9: 1; v/v) of about 155 nm, 157 nm, 169 nm for Na+F?, Na+AcO?, and Na+AsO2 ? ions with LOD of 0.23 ppm, 0.18 ppm, and 0.30 ppm, respectively. The observed spectral change of receptor R2 is due to the anion-induced deprotonation of the OH proton, which is confirmed by UV–vis titration, 1HNMR titration, and cyclic voltammetric studies. Theoretical studies via DFT calculation were carried for R1 and R2 to optimize the structure and to explain the anion-binding mechanism. The application of designed receptor R2 was successfully demonstrated for the detection of F? and AsO2 ? ions using a test strip. The receptors R1 and R2 proved itself to be potentially useful for real-life application by sensing F? and AcO? ions in real samples like toothpaste, mouthwash, vinegar and seawater in a complete aqueous medium. © 2019 Elsevier B.V.Item Design and synthesis of malonohydrazide based colorimetric receptors for discrimination of maleate over fumarate and detection of F?, AcO? and AsO2 ? ions(Elsevier B.V., 2020) Singh, A.; Mohan, M.; Trivedi, D.R.In this study, we have designed and synthesized two new organic receptors R1 and R2 based on malonohydrazide for the recognition of biologically important anions. The receptor R1 capable of colorimetric discrimination of maleate over fumarate ion, exhibit significant color change from pale yellow to wine red due to intermolecular hydrogen bond between the R1 and maleate ion, supported by 1HNMR titration, where the peak at ?12.0 ppm attributed to the NH proton experiences a downfield shift upon binding with maleate ion. Receptor R1, equipped with two electron-withdrawing [sbnd]NO2 moieties as the chromogenic signaling unit enhance the hydrogen bonding tendency and acidity, and thus when comparing with receptor R2, R1 displayed substantial higher redshift (??max) of 148 nm, 143 nm, and 140 nm towards F?, AcO?, and maleate anion in the DMSO. In addition, the synthesized receptors R1 and R2 are able to detect F?, AcO?, and AsO2 ? ions as their sodium salts in an aqueous solution with visual color change. Receptor R1 exhibit electrochemical response towards F? and AcO? ions. The receptors R1 and R2 are successfully applied for quantitative detection of F? ion in the toothpaste solution in an aqueous medium. Additionally, R1 and R2 exhibit fluorescence enhancement towards F? and AcO? ions in the DMSO. As well, R1 and R2 demonstrate to be potentially useful colorimetric chemosensor for sensing maleate ion using the test strip. The theoretical calculation based on TD-DFT corroborates well with the experimental results of the receptors R1 and R2 with fluoride, acetate and maleate. © 2019 Elsevier B.V.