Faculty Publications
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Item Selective detection of mercury ions using benzothiazole based colorimetric chemosensor(Elsevier B.V., 2016) Momidi, B.K.; Tekuri, V.; Trivedi, D.R.Three new receptors L1, L2 and L3 were designed and synthesized in a single pot synthesis. The synthesized receptors were characterized by 1H NMR, FT-IR and Mass spectrometry. The cation binding affinity was studied using colorimetric and UV–Vis spectral methods for the three receptors. Receptor L1 showed high selectivity with a significant color change from yellow to colorless (turn-off response) in the presence of Hg2 + ions over the other cations such as, Ni2 +, Cr3 +, Pb2 +, Cu2 +, Cd2 +, Co2 +, Zn2 + and Fe2 + and the receptor L2, L3 did not show any color change or change in the absorption in UV–Vis spectral studies with Hg2 + ions and other tested metal ions, this may be due to lack of –OH group in receptor L2 and L3. The B-H Plot shown 1:1 complex between L1and Hg2 + ions. © 2016 Elsevier B.V.Item Pharmaceutical Co-Crystal of Flufenamic Acid: Synthesis and Characterization of Two Novel Drug-Drug Co-Crystal(Elsevier B.V., 2017) Nechipadappu, S.K.; Tekuri, V.; Trivedi, D.R.Two novel pharmaceutical co-crystals of anti-inflammatory drug flufenamic acid (FFA) with 2-chloro-4-nitrobenzoic acid (CNB) and ethenzamide (ETZ) have been synthesized by solvent evaporation method as well as by solvent drop-assisted grinding method. The synthesized co-crystals were characterized thoroughly by various spectroscopic methods and crystal structures were determined by single-crystal x-ray diffraction technique. In FFA-CNB co-crystal, robust supramolecular acid-acid homosynthon was observed. FFA-ETZ co-crystal is formed via robust supramolecular acid-amide heterosynthon. In FTIR spectra, a significant shift in the carbonyl stretching frequency was observed for the co-crystals due to the presence of intermolecular hydrogen bond. 1H nuclear magnetic resonance study suggests the presence of hydrogen bond in the solution state of FFA-ETZ co-crystal; however, it was absent for FFA-CNB co-crystal. Solubility study in Millipore water revealed that the solubility of FFA is increased by 2-fold when it is in the form of FFA-CNB co-crystal and no increment in the solubility of FFA was observed in FFA-ETZ co-crystal. About 5-fold increment in the solubility of FFA was observed in both the co-crystals in 0.1 N HCl (pH 1) solution. The synthesized co-crystals were found to be non-hygroscopic at ?75% relative humidity and stable for a period of 6 months at ambient temperature (?25°C). © 2017 American Pharmacists Association®Item A new colorimetric chemosensors for Cu2+ and Cd2+ ions detection: Application in environmental water samples and analytical method validation(Elsevier B.V., 2017) Tekuri, V.; Trivedi, D.R.A new heterocyclic thiophene-2-caboxylic acid hydrazide based chemosensor R1 to R4 were designed, synthesized and characterized by various spectroscopic techniques like FT-IR, UV-Vis, 1H NMR, 13C NMR, Mass and SC-XRD. The chemosensor R3 showed a significant color change from colorless to yellow in the presence of Cu2+ ions and chemosensor R4 showed a significant color change from colorless to yellow in the presence of Cd2+ ions over the other tested cations such as Cr3+, Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Zn2+, Ag2+, Al3+, Pb2+, Hg2+, K+, Ca2+ and Mg2+. The high selective and sensitivity of R3 towards Cu2+ and R4 towards Cd2+ ions was confirmed by UV-Vis spectroscopic study. The R3 showed a red shift in the presence of Cu2+ ions by ??max 67 nm and R4 showed a red shift in the presence of Cd2+ ions by ??max 105 nm in the absorption spectrum. The binding stoichiometric ratio of the complex between R3 - Cu2+ and R4 - Cd2+ ions have been found to be 1:1 using the B-H plot. Under optimized experimental conditions, the R3 and R4 exhibits a dynamic linear absorption response range, from 0 to 50 ?M for Cu2+ ions and 0 to 30 ?M for Cd2+ ions, with the detection limit of 2.8 × 10?6 M for Cu2+ and 2.0 × 10?7 M for Cd2+ ions. The proposed analytical method for the quantitative determination of Cu2+ and Cd2+ ions was validated and successfully applied for the environmental samples with good precision and accuracy. © 2017 Elsevier B.V.Item Multi-signaling thiocarbohydrazide based colorimetric sensors for the selective recognition of heavy metal ions in an aqueous medium(Elsevier B.V., 2017) Momidi, B.K.; Tekuri, V.; Trivedi, D.R.A series of colorimetric chemosensors R1–R6 have been developed from thiocarbohydrazide derivatives, for the selective detection of heavy metal ions. The structures of the receptors R1–R6 were well characterized by standard spectroscopic techniques like FT-IR, 1H NMR, and ESI-MS. The solid structure of receptor R1 and R2 were derived by single crystal X-ray diffraction (SC-XRD). The cation reorganization abilities of receptors R1–R6 were studied by UV–Vis spectroscopy. The receptors R1, R3 and R4 acts as a tremendous sensitive probe for heavy metal ions (Hg2 +, Cd2 + and Pb2 +) with the ?M detection (R1 for Hg2 +, 2.72, R3 for Cd2 +, 3.22, R4 for Hg2 +, Cd2 + & Pb2 +, 0.70, 0.20 & 0.30 ?M) and the receptors R2, R5 & R6 are sensitive towards Cu2 + ions with the ?M detection (3.34, 0.90 & 1.20 ?M) in an aqueous medium among all other tested cations. The receptor R4 shows a multi-color response towards Hg2 +, Cu2 +, Cd2 + and Pb2 + ions. The recognition mechanism, stoichiometric binding ratio and detection limit (DL) have been examined by UV–Visible spectroscopic titration experiments and Benesi-Hildebrand (B-H) plot, receptor R1–R6 sowed 1:1 binding ratio with good binding constant range of 103 to 105 M? 1 with Hg2 +, Cu2 +, Cd2 + and Pb2 + ions metal ions. © 2017 Elsevier B.V.Item Selective colorimetric chemosensor for the detection of Hg2+ and arsenite ions using Isatin based Schiff's bases; DFT Studies and Applications in test strips(Elsevier B.V., 2019) TG, A.K.; Tekuri, V.; Mohan, M.; Trivedi, D.R.Three isatin appended Schiff's base chemosensors (CS1-CS3) were synthesized and characterized by FT-IR, 1H-NMR, 13 C-N MR, and LC–MS. The sensing ability of the synthesized chemosensors towards Hg2+ and AsO2? ions was established through colorimetric / UV–vis techniques and achieved detection limit at ppm levels. All chemosensors CS1-CS3 exhibited rapid colorimetric / UV–vis response with Hg2+, also, CS1 and CS3 displayed dual-ion selectivity towards AsO2? (colour changes orange to aqua-blue) and Hg2+ (from orange to colorless). The binding properties and detection limit has been examined through the UV–vis instrument. The mechanism of binding was investigated using various analytical techniques like FT-IR, UV–vis, mass and 1H-NMR titration experiments. The experimental results were supported by theoretical DFT study. The developed colorimetric chemo-sensors showed a good binding affinity towards metal ions and exhibited good linearity (R2 ? >0.99). Further, the developed sensors were used for test strips application to detect the Hg2+, AsO2? ions and achieved naked-eye detection at ppm levels. Hence, CS1-CS3 sensors find its practical application in efficient detection of toxic metals like Hg2+ and AsO2?. © 2018 Elsevier B.V.Item Hg 2+ induced hydrolysis of thiazole amine based Schiff base: Colorimetric and fluorogenic chemodosimeter for Hg 2+ ions in an aqueous medium(Elsevier B.V., 2019) Tekuri, V.; Sahoo, S.K.; Trivedi, D.Simple pyrene-based chemosensors 1 to 3, were synthesized from pyrene-1-carboxaldehyde and they were characterized using various spectroscopic techniques like UV–Vis, FT-IR, Mass, 1 H NMR and 13 C NMR. Among synthesized receptors, the receptor 1 shows high selectivity towards Hg 2+ ions. Further, the high selectivity of receptor 1 towards Hg 2+ ions in the presence of various other interfering metal ions like Ni 2+ , Zn 2+ , Mn 2+ , Co 2+ , Cu 2+ , Cr 3+ , Fe 3+ , Al 3+ , Ag + , Fe 2+ , Cd 2+ , Mg 2+ , Pb 2+ , Ca 2+ , Na + , K + was confirmed by UV–Vis and fluorescence methods. The detection limit for Hg 2+ ions was found to be 0.270 ?M. The chemodosimetric irreversible hydrolysis of the receptor 1 in the presence of Hg 2+ was studied by UV/Vis, fluorescence, FT-IR, LC-MS, 1 H NMR and theoretical DFT study. Further, the real life applications of receptor 1 for the determination of Hg 2+ ions were demonstrated by UV–Vis method. © 2019 Elsevier B.V.Item Smart Colorimetric Chemosensors for Multi-Analyte Signaling: Recognition of Heavy Metal Ions in an Aqueous Medium and DFT Studies(Wiley-Blackwell info@wiley.com, 2020) Tekuri, V.; Mohan, M.; Trivedi, D.R.A Schiff's base colorimetric chemosensors R1–R3 consist of carbohydrazide, and heterocyclic aldehydes have been designed and synthesized for sensing of heavy metal ions. Synthesized receptors were well characterized by various standard spectroscopic techniques. The receptor R1 exhibited multi-ion selectivity for Cd2+, Hg2+, Pb2+, Cu2+ ions and showed lowest detection limit of 1.9 ppb, for Cd2+ & Hg2+ ions. The receptors R2 and R3 displayed dual ion selectivity (R2 for Hg2+, Cu2+, and R3 for Cu2+, AsO2 – ions) in an aqueous medium at ppb levels. The UV–Vis and colorimetric studies confirmed the selectivity and sensitivity of chemosensors R1–R3 in the presence of other interfering metal ions. Further, using the B–H plot, FT-IR, and mass analysis data, the binding modes, stoichiometric ratios of receptors R1–R3 with the metal ions were investigated. The estimated association constant values were found to be 104 to 105 M–1/M–2. The experimental results are well concordant with that of calculated theoretical DFT results. The receptors R1–R3 exhibited good sensitivity and selectivity compared to literature reports and successfully demonstrated for test strip applications. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim