Faculty Publications
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Item Colorimetric chemosensors for the detection of environment-polluting arsenite and cyanide(wiley, 2023) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.Due to the biotic and ecological implications of extremely deadly cyanide and arsenite ions, the design, manufacturing, and development of cyanide and arsenite chemosensors has been a particularly active study subject in recent decades. The main works on colorimetric/fluorimetric chemosensor sensing mechanisms and their application in cyanide and arsenite detection are summarized and highlighted. This book chapter categorizes cyanide sensors based on their structure, while arsenite sensors are segregated based on their detecting mechanism strategies. This chapter provides a detailed summary of current research in this field and will be valuable in creating and synthesizing novel cyanide and arsenite chemosensors. © 2024 WILEY-VCH GmbH. Published 2024 by WILEY-VCH GmbH. All rights reserved.Item Substituent effect on colorimetric detection of biologically and environmentally relevant anions: Insight in real-life applications(Elsevier B.V., 2019) Singh, A.; Girish Gowda, R.; Trivedi, D.A new set of chromogenic anion receptors R1-R4 have been synthesized with a different substituent, including electron withdrawing (nitro moiety in R1), conjugated group (naphthyl in R2), and electron donating (methyl in R3), respectively. The receptors R1-R4 exhibited very good sensitivity towards the F ? and AcO ? anions in the DMSO. In addition, R1 showed selectivity towards H 2 PO 4 ? ions over other tested anions. R1 especially acted as an effective sensor for sodium salts of F ? , AcO ? , AsO 2 ? , and AsO 4 2? ions in an aqueous medium due to the presence of two electron-withdrawing nitro substituents, which showed hydrogen bond donor tendency and acidity of the OH proton. This result indicates that R1 is highly capable of competing with an aqueous medium to detect anions without counter Na + ion interference. Interestingly, R1 displays solvatochromic property in the presence of AcO ? ions in different aprotic solvents. Additionally, the receptor R1 shows high binding affinity towards AcO ? ions in the buffer medium (DMSO: HEPES, 9:1 v/v), which displayed remarkable colour change from pale yellow to blue with a large ?? red shift of 170 nm. The CV studies reveal the deprotonation of the -NH proton upon interaction with the AcO ? ions. The receptor R1 is subjected to practical application to sense F ? and AsO 2 ? ions using the test strip. In addition, the receptor R1 proves itself as a potential applicant for the detection of F ? ions quantitatively in commercially available mouthwash. © 2019 Elsevier B.V.Item Chromogenic detection of fluoride, dihydrogen phosphate, and arsenite anions based on 2,4-dinitrophenyl hydrazine receptors: spectral and electrochemical study(Taylor and Francis Ltd., 2021) K, N.; Singh, A.; Nityananda Shetty, A.N.; Trivedi, D.R.The colorimetric recognition of biologically relevant fluoride (F?), acetate (AcO?), and dihydrogen phosphate (H2PO4?) ions, and poisonous arsenite (AsO2?) ions, was devised and new receptors for these anions synthesised via the Schiff base condensation procedure. UV–visible titration, fluorescence titration, 1H-NMR titration, and cyclic voltammetry were used to explore the interactions of receptors R1–R3 with anions and possible detection mechanisms. The synthesised probes could sense inorganic fluoride, acetate, dihydrogen phosphate, and arsenite in the organo–aqueous medium (H2O/ Dimethylsulphoxide, 1:?9, v/v) and displayed a change in colour detectable to the naked eye. Out of the three synthesised receptors, receptor R1 showed better sensing ability of fluoride, acetate, dihydrogen phosphate, and arsenite ions in the organo–aqueous medium with a lower detection limit of 0.1 ppm, 0.171 ppm, 0.194 ppm, and 0.144 ppm, respectively. All three receptors formed complexes with the anions through H-bonding interaction followed by deprotonation of the NH proton. © 2022 Informa UK Limited, trading as Taylor & Francis Group.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 sensors for discriminatory detection of arsenite ions: Application in milk, honey and water samples and molecular logic gates(Elsevier Inc., 2024) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.Millions of people are exposed to dangerous arsenic levels in drinking water, highlighting the urgent need for affordable, continuous on-site arsenic monitoring methods. It is crucial to specifically detect arsenite among inorganic arsenic anions because it is more poisonous than arsenate. Addressing these concerns, the present study developed 5-(4-nitrophenyl)-2-furaldehyde based two colorimetric chemosensors, N5R3 and N5R4, with different signaling groups for the selective detection of arsenite anions over arsenate in DMSO/H2O (6:4, v/v). The red-shift in the UV–Vis absorption spectra supported the distinct color changes of sensors N5R3 and N5R4 displayed upon binding with arsenite. Sensors demonstrated stability over a pH range of 6 to 12 and exhibited stability over a considerable time period. Among the chemosensors, N5R3 exhibited the lowest detection limit of 7.41 ppb with a high binding constant of 2.9976 × 106 M?1 for arsenite. The 1:1 binding interactions between the chemosensors and arsenite were confirmed using B-H plot and Job's plot analysis. The intramolecular charge transfer (ICT) mechanism for detecting arsenite was proposed through UV and 1H NMR titrations, electrochemical studies, mass spectral analysis and DFT calculations. The interactions between the sensor and arsenite anions were further analyzed using global reactivity parameters (GRPs). Practical applications were demonstrated through the utilization of test strips and molecular logic gates. Both chemosensors efficiently recognized arsenite in real water, honey, and milk samples. © 2024 Elsevier B.V.Item Julolidine-hydrazide-based D-?-A fluorescent chemoprobes for detection of Al3+ and Differentiation of Arsenic species: Applications in portable test strips, ecological assessment, and DFT studies(Elsevier Inc., 2024) Hebbar, S.D.; K A, S.; Raval, K.; Trivedi, D.R.In this study, a novel donor-?-acceptor (D-?-A) chemoprobe was synthesized using julolidine and hydrazide derivatives. The probes S1R1 and S1R2 demonstrated promising capabilities in sensing Al3+ and AsO2- ions through fluorescence. Specifically, probes S1R1 and S1R2 exhibited selectivity towards detecting Al3+ ions, with detection limits of 0.0485 ppm and 0.1754 ppm, respectively. These probes were effectively applied in environmental monitoring for detecting Al3+ ions in various samples, including natural water, soil, pharmaceutical tablets, and E.coli cells, and also a portable test strip for the easy detection of Al3+ ions. Moreover, probe S1R2 showed discriminative detection of AsO2- over AsO43- ions in semi-aqueous media, with a detection limit of 0.1055 ppm. This discrimination ability is attributed to the lower hydration energy of AsO2- ions compared to AsO43- ions, enabling preferential binding to S1R2. The observed turn-on fluorescence performance of probes S1R1 and S1R2 upon the addition of Al3+ ions are attributed to the chelation-enhanced fluorescence (CHEF) phenomenon. Additionally, live cell imaging experiments demonstrated that probes S1R1 and S1R2 can effectively detect Al3+ ions within E.coli cells using a Cell imaging reader. © 2024 Elsevier B.V.Item Selective chromogenic nanomolar level sensing of arsenite anions in food samples using dual binding site probes(Elsevier Ltd, 2025) K, K.; Nityananda Shetty, A.N.; Trivedi, D.R.In the present study, two chromogenic probes, N7R2 and N7R3, each containing two binding sites, were designed and synthesized for the selective detection of arsenite in DMSO/H2O (1:1, v/v). The probes exhibited stability across a pH range spanning from 5 to 12. The lower detection limits of 2.01 ppb (18.86 nM) for N7R2 and 1.79 ppb (16.75 nM) for N7R3, which are much lower than the WHO recommended permissible limit of arsenite, confirmed the superior efficiency of the probes in detecting arsenite. The detection mechanism for arsenite was proposed through UV and 1H NMR titrations, electrochemical studies, and DFT calculations. Practical applications were demonstrated through the fabrication of test strips and molecular logic gates. The probes efficiently recognized arsenite in real water, honey, milk samples, and fruit/vegetable juices. Both N7R2 and N7R3 exhibited excellent recovery rates in the analysis of food samples, demonstrating the probes' usefulness in real sample analysis. © 2024Item Heterocyclic-based optical responsive chemosensors for the detection of arsenite and phosphate in semi-aqueous medium: Application in logic gate operations, RGB tool, and DFT studies(Elsevier B.V., 2025) Hebbar, S.D.; Trivedi, D.R.Highly selective and sensitive organic chemosensors S2R1-S2R3 were synthesized using thienyl-substituted pyridine derivative and characterized by various spectroscopic techniques. The effect of substituents on selectivity is observed in the chemosensors S2R1 through S2R3, with the rate of reactivity toward ions following the trend as -NO2 > -CN > –OCH3 group. The chemosensor S2R1 exhibited selectivity towards arsenite and phosphate, achieving a Limit of Detection (LOD) of 0.2672 ppm and 0.5042 ppm, respectively, in 30% aq. (CH3)2SO solution. It was also observed that S2R2 was selective for PO43? ions in 100% (CH3)2SO solution with an LOD of 0.521 ppm. The spectral redshifts observed in the organo-aqueous media potentializes the sensor to be colorimetrically active. The probe S2R1 showed the lowest LOD and high binding constant with AsO2? and PO43? ions. Other characterization techniques, such as electrochemical studies, 1H NMR titration, UV–visible titration, and DFT experiments, demonstrated the sensing mechanism of arsenite and phosphate ions with the chemosensors through an intermolecular hydrogen bonding and intermolecular charge transfer (ICT) process followed by its practical applicability for real world-sensing. © 2024 Elsevier B.V.