Faculty Publications
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Publications by NITK Faculty
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Item Dual colorimetric receptor with logic gate operations: Anion induced solvatochromism(Royal Society of Chemistry, 2014) Kigga, M.; Swathi, N.; Manjunatha, J.R.; Das, U.K.; Nityananda Shetty, A.N.; Trivedi, D.R.A receptor R1 was designed and synthesised for colorimetric detection of F- ions as well as Cu2+ ions via intramolecular charge transfer mechanism. Upon addition of F- ions in dry DMSO, the color of the receptor R1 changed from pale yellow to blue. The receptor showed a unique property of solvatochromism by displaying different coloration with different solvents only in the presence of F- ions, which were applied to determine the percentage composition of binary solvent mixtures. The receptor R1 was able to detect Cu2+ ions colorimetrically where it exhibited a color change from pale yellow to orange-red. In addition, the receptor was subjected to molecular logic gate applications, wherein it showed 'ON-OFF' switching operations. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.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 Colorimetric and fluorometric turn-on sensor for selective detection of fluoride ions: Sol-gel transition studies and theoretical insights(Royal Society of Chemistry, 2018) Pangannaya, S.; Mohan, M.; Trivedi, D.R.A new organic receptor R1 based on a naphthyl unit covalently linked to a long alkyl chain has been designed, synthesized and characterized by standard spectroscopic techniques. The colorimetric response of receptor R1 from colorless to a pale yellow color and blue fluorescence emission in the presence of F- ions revealed its selective sensing ability in the solution phase. UV-Vis titration, fluorescence titration and 1H NMR titration studies confirmed the formation of the R1-F- complex. Receptor R1 formed a stable gel in DMSO and was confirmed through the standard heating-and-cooling method. Addition of F- ions resulted in disruption of the gel forming a solution that exhibited blue fluorescence emission. The binding constant of the R1-F- complex was found to be of the order of 5.9 × 105 M-1. DFT studies revealed the formation of the receptor-anion complex agreeing well with the experimental results. The detection limit was calculated and found to be 0.8 ppm, implying the potential for application of receptor R1 in environmental applications. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Discriminative ion detection of Hg2+ and Cu2+ and selective recognition of PO43? ions: Real time monitoring in food and water samples and molecular keypad lock integration(Elsevier B.V., 2025) Hebbar, S.D.; Trivedi, D.R.A series of sensors, designated S3R1-S3R4, were designed and synthesized for the detection of PO43? ions and toxic metals, specifically Hg2+ and Cu2+ ions. The colorimetric detection of PO43? ions using these sensors exhibited a distinct visual color transition from yellow to purple in organo-aqueous media. The intrinsic cavity-like structure in the thiosemicarbazide-based derivative S3R4 significantly enhances the binding affinity for Hg2+ and Cu2+ ions in organic media. Utilizing UV–visible spectroscopic techniques and electrochemical investigations, the binding constants, stoichiometric ratios, limits of detection (LOD), and the electrochemical properties of the sensor-ion complexes were comprehensively characterized alongside their stability. Density Functional Theory (DFT) validation studies elucidated the binding mechanisms involved in the ion detection process. The LOD for PO43? with S3R1 was determined to be 0.28 ppm, while the LODs for Hg2+ and Cu2+ with S3R4 were found to be 0.15 ppm and 0.15 ppm, respectively. The significant binding constants and detection limits underscore the potential of S3R1-S3R4 as real-time sensors for detecting PO43?, Cu2+, and Hg2+ ions in environmental applications. Furthermore, the integration of molecular keypad locks and logic gate constructions highlights the applicability of these sensors in molecular communication systems. © 2025 Elsevier B.V.