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 Recent advances in the fluorescent and colorimetric detection of dihydrogen phosphate(Taylor and Francis Ltd., 2021) K, N.; Nityananda Shetty, A.N.; Trivedi, D.R.In biological systems, phosphates and their derivatives show vital roles in signal transduction and storing of energy. Due to the biotic and chemical importance of dihydrogen phosphate, the detection of the anion has gained greater focus in the area of sensing and supramolecular chemistry. Among the various methods, colorimetric and fluorescent recognition provides a simple and easy way of detection without the need for sophisticated instrumentation and technical skills. The present review focuses on highlighting the colorimetric and fluorescent detection of dihydrogen phosphate (H2PO4−) via various detection mechanisms. This review divides the content into six major subtitles (i) Chemosensors based on H- bonding interaction (ii) Chemosensors based on deprotonation mechanism (iii) Chemosensors based on charge transfer interaction (iv) Chemosensors based on photoinduced electron transfer (v) Macrocycles as chemosensors (vi) Metal complexes as chemosensors. In each subdivision, more attention has been given to the detailed mechanism of detection. © 2022 Informa UK Limited, trading as Taylor & Francis Group.Item Supramolecular synthons in noncovalent synthesis of a class of gelators derived from simple organic salts: Instant gelation of organic fluids at room temperature via in situ synthesis of the gelators(2009) Das, U.K.; Trivedi, D.R.; Adarsh, N.N.; Dastidar, P.(Chemical Equation Presented) The supramolecular synthon approach has been employed to synthesize noncovalently a series of low molecular mass organic gelators (LMOGs) derived from benzylammonium salts of variously substituted benzoic acids. The majority of the salts (75%) prepared showed interesting gelation properties. Instant gelation of an organic fluid, namely methyl salicylate, was achieved at room temperature by using most of the gelator salts by in situ synthesis of the gelators. Table top rheology and scanning electron microscopy (SEM) were used to characterize the gels. Single crystal X-ray diffraction studies revealed the presence of both 1D and 2D supramolecular synthons. X-ray powder diffraction (XRPD) studies indicated the presence of various crystalline phases in the fibers of the xerogels. By using these data, a structure-property correlation has been attempted and the working hypothesis for designing the gelator has been reinforced. © 2009 American Chemical Society.Item Colorimetric receptors for naked eye detection of inorganic fluoride ion in aqueous media using ICT mechanism(Royal Society of Chemistry, 2012) Kigga, M.; Nityananda Shetty, A.N.; Trivedi, D.R.A new series of receptors were designed and synthesized based on benzohydrazide for the colorimetric detection of fluoride ion. The receptors L1 and L2 are highly selective towards fluoride ion over other anions. These receptors are able to detect inorganic fluoride such as NaF in aqueous solutions. The presence of two carbonyl groups in the receptor molecule makes the -NH proton highly acidic and hence these receptors are capable of competing with water molecules to bind fluoride ion. The receptors L1 and L2 showed a significant colour change from colourless to yellow in aqueous solutions of NaF with a ??max of 149 nm and 147 nm respectively. The mechanism involved in the colour change was deprotonation, formation of imidic acid intermediate followed by stabilization of complex through Intramolecular Charge Transfer (ICT). This was further confirmed by 1H NMR titrations where the formation of imidic acid was observed. The receptor L1 proved itself to be potentially useful for real-life applications by detecting fluoride ion quantitatively in sea water and commercially available mouth wash. © 2012 The Royal Society of Chemistry.Item Condensation of malononitrile with salicylaldehydes and o-aminobenzaldehydes revisited: Solvent and catalyst free synthesis of 4H-chromenes and quinolines(Royal Society of Chemistry, 2012) Bhat, S.I.; Choudhury, A.R.; Trivedi, D.R.The reaction of malononitrile with salicylaldehyde under solvent and catalyst free conditions was re-investigated using mechanochemical mixing, thermal heating and a direct crystallization process. The resulting condensation product by all three types of molecular activation, was found to be (2-amino-3-cyano-4H-chromene-4-yl)malononitrile, which is not the previously reported benzofuran-2-carbonitrile. The structure of the resulting chromene derivative was confirmed by FT-IR, MS, 1H, 13C NMR and single crystal and powder X-ray diffraction. The reaction pathway under neat conditions (mechanochemical mixing) at ambient temperature was monitored by IR spectral measurements. The versatility of the current green protocol was examined through the reaction of eleven derivatives of o-hydroxybenzaldehyde with malononitrile to obtain 2-amino-3-cyano-4H-chromene derivatives. In addition, malononitrile was further reacted with o-aminobenzaldehydes under neat conditions to yield quinoline derivatives. © 2012 The Royal Society of Chemistry.Item Fast and efficient synthesis of N-substituted ?-aminobutyric acids by grinding at room temperature(Springer Verlag, 2013) Bhat, S.I.; Trivedi, D.R.Green chemistry is gaining increasing interest due to the growing awareness of the chemical community for sustainable development. Green chemistry solutions include synthesis without solvent and catalyst because many solvents and catalysts are toxic and expensive. Herein, we report the solvent and catalyst free method for the synthesis of N-substituted derivatives of ?-aminobutyric acid by direct aza-Michael addition of amines to crotonic acid. The protocol involves simple mixing or grinding the reactants at room temperature. The ?-amino acid derivatives were obtained in 82-100 % yield with a short reaction time without any tedious workup procedures. Our findings thus reveal a promising alternative to previously used procedures. © 2013 Springer-Verlag Berlin Heidelberg.Item A catalyst- and solvent-free three-component reaction for the regioselective one-pot access to polyfunctionalized pyrroles(2013) Bhat, S.I.; Trivedi, D.R.A facile method for the regioselective synthesis of tetrasubstituted pyrroles, from readily accessible 1,3-dicarbonyls, benzoin derivatives and ammonium acetate, has been developed. The one-pot three-component reactions were performed to afford tetrasubstituted pyrroles under solvent- and catalyst-free conditions. © 2013 Elsevier Ltd. All rights reserved.Item 4-Nitrobenzoic acid-sulfathiazole (1/1)(2014) Oruganti, M.; Trivedi, D.R.In the crystal structure of the title compound, C7H 5NO4·C9H9N3O 2S2, the sulfathiazole and 4-nitrobenzoic acid molecules are held together by short ?-? contacts between the thiazole and nitrobenzene rings, with a centroid-centroid distance of 3.8226(7)Å. The sulfathiazole molecules form dimers via N-H.N hydrogen bonds involving the thiazole and sulfonamide moieties, owing to the fact that sulfathizole exhibits amide-imide tautomerism. The N-H (amine) groups of two sulfathiazole molecules are linked to the two S=O groups of a sulfathiazole via N-H.O hydrogen bonds. Two molecules of coformer are held together by O-H.O hydrogen bonds. These units self-assemble, forming a three-dimensional network stabilized by (acid)C-H.?(sulfathiazole benzene ring) interactions.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 Receptor with an active methylene group as binding site for extraction of inorganic fluoride ions from seawater(Wiley-VCH Verlag info@wiley-vch.de, 2014) Kigga, M.; Trivedi, D.R.Two new receptors R1 and R2 based on triphenylphosphonium salts with an active methylene group as binding site have been designed and synthesised for the detection of F- ions. The detection limit of these receptors in organic media was found to be 0.2 ppm. Upon adding F- ions, a ??max of 188 nm and 256 nm was observed for receptors R1 and R2, respectively. The detection process followed deprotonation of the methylene proton, which has been confirmed by 1H NMR titration. The receptors were evaluated for real-life applicability by extracting F- ions from aqueous media and seawater into organic media. Receptor R2 was able to extract F- ions from seawater with 99 % efficiency. The level of F- ions present in seawater has been quantified and found to be 1.4 ppm, which is comparable to the reported literature value. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.