Faculty Publications
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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 Colorimetric anion sensors based on positional effect of nitro group for recognition of biologically relevant anions in organic and aqueous medium, insight real-life application and DFT studies(Elsevier B.V., 2018) Singh, A.; Sahoo, S.K.; Trivedi, D.R.A new six colorimetric receptors A1-A6 were designed and synthesized, characterized by typical common spectroscopic techniques like FT-IR, UV–Visible, 1H NMR, 13C NMR and ESI-MS. The receptor A1 and A2 exhibit a significant naked-eye response towards F? and AcO? ions in DMSO. Due to presences of the NO2 group at para and ortho position with extended ?-conjugation of naphthyl group carrying –OH as a binding site. Compared to receptor A2, A1 is extremely capable of detecting F? and AcO? ions present in the form of sodium salts in an aqueous medium. This is owed to the occurrence of –NO2 group at para position induced in increasing the acidity of –OH proton. Consequently, it easily gets deprotonated in aqueous media. The detection limit of receptor A1 was turned out to be 0.40 and 0.35 ppm for F? and AcO? ions which is beneath WHO permission level (1.0 ppm). Receptor A1 shows a solitary property of solvatochromism in different aprotic solvents in presence of AcO? ion. Receptor A1 depicts high selectivity towards AcO? ion in DMSO: HEPES buffer (9:1, v/v). Receptor A1 proved itself for real life application by detecting anion in solution and solid state. The binding mechanism of receptor A1 with AcO? and F? ions was monitored from 1HNMR titration and DFT study. © 2017 Elsevier B.V.Item Photophysical and electrochemical properties of organic molecules: Solvatochromic effect and DFT studies(Elsevier B.V., 2018) Mohan, M.; Pangannaya, S.; Satyanarayan, M.N.; Trivedi, D.R.A series of five Schiff base molecules M1, M2, M3, M4 and M5 have been designed and synthesized by aldol condensation reaction. Synthesized molecules have been characterized by standard spectroscopic techniques in order to confirm their structural traits. The solvatochromic behavior of molecules M1 to M5 in solvents of varying polarity were investigated by UV–Vis, fluorescence spectroscopy and supported by TD-DFT calculations. DFT studies performed in the gas phase confirmed the energy stabilized structure of the molecules M1 to M5. Structural characteristics of molecule M2 favored higher fluorescence emission with a quantum yield of 0.35 and a solid-state emission of 512 nm. Fluorescence lifetime measurement of the molecules M1 to M5 exhibited a lifetime of order 2–5 ns. Overall, molecule M2 can find its application in organic light emitting diodes as a non-dopant emitter material. © 2018 Elsevier B.V.