Journal Articles
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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 Aminophenol based colorimetric chemosensor for naked-eye detection of biologically important fluoride and acetate ions in organo-aqueous medium: Effective and simple anion sensors(Elsevier B.V., 2018) Singh, A.; Tom, S.; Trivedi, D.R.Three new novel colorimetric receptors (R1-R3) based on aminophenol have been designed and synthesized by simple Schiff base reaction and their anion sensing properties were examined, characterized by common spectroscopic techniques such as FT-IR, UV–visible, 1HNMR,13CNMR, ESI–MS and fluorescence. Receptors R1 and R2 bearing ?OH group at ortho and para position acting as anion binding sites with –NO2 moiety as an optical signaling unit. Receptors R1 and R2 elevated selective and sensitive ability towards F? and AcO? ions over the other competing anions in DMSO as well as in CH3CN. Receptors R1 and R2 showed high capability of sensing acetate and fluoride ions present in the form of sodium salts such as NaAcO and NaF in an aqueous medium. The color of both the receptors R1 and R2 solution changes from pale green to blue and pale yellow to peach color with the addition of sodium salts of acetate (NaAcO) and fluoride (NaF) with a bathochromic shift of 168 nm and 165 nm in the UV–vis absorption spectra of receptor R1 and 103 nm and 100 nm in case of receptor R2 due to ICT transition between the electron rich ?OH and electron deficient –NO2 moiety. Moreover, receptors R1-R2 showed noteworthy fluorescence enhancement, response towards F? and AcO? ion in DMSO. Compared to receptor R2, R1 shows a huge red shift towards F? and AcO? ions in organo-aqueous medium due to the presence of ?OH proton at ortho position which effectively bind with both the anions. The binding constant and stoichiometry of the receptors-anions complex was calculated by using Benesi-Hildebrand (B–H) plot. The anion binding properties of receptor R1 via ICT mechanism was enlightened by UV–vis titration, 1HNMR studies. © 2017 Elsevier B.V.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 Simple one-pot sonochemical synthesis of copper sulphide nanoparticles for solar cell applications(Elsevier B.V., 2019) Singh, A.; Ramachandran, R.; Noyel Victoria, S.Copper sulphide nanoparticles for solar cell applications were synthesized by a single step sonochemical method using copper acetate and thiourea as precursors. The effects of sonication time, ultrasonic bath temperature and annealing temperature on particle properties were studied. Synthesized particles were characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction spectrophotometer and UV–visible spectrophotometer. The particles were found to be a mixture of chalcocite, covellite and djurleite. The optical band gap of the particles was found to be in the range of 1.6–2.1 eV. Heat treatment of the particles was found to give rise to needle shaped particles while a bath temperature of 55 °C yielded few nanoplates. © 2015 The AuthorsItem Chemosensor Based on Hydrazinyl Pyridine for Selective Detection of F? Ion in Organic Media and CO3 2? Ions in Aqueous Media: Design, Synthesis, Characterization and Practical Application(Wiley-Blackwell info@wiley.com, 2019) Singh, A.; Mohan, M.; Trivedi, D.Two new organic receptors, receptors R1 and R2 based on hydrazinyl pyridine have been synthesized for colorimetric detection of fluoride, acetate, and carbonate anions. Receptor R1 selectively recognizes fluoride ions over the other interference anions in the dimethyl sulfoxide based on hydrogen bonding interaction, followed by deprotonation and reflects 1:2 complex formation between the receptor and the fluoride ion. Noticeable, R2 is able to discriminate between fluoride and acetate ions via optical changes despite similar basicity with bathochromic shift of 215 nm and 194 nm. In addition, R1 and R2 exhibit splendid selectivity toward carbonate ions in the aqueous media via visible colour change from pale yellow to aqua with detection limit of 0.51 ppm and 0.47 ppm. The binding mode of fluoride and carbonate to receptor R1 and R2 is supported by Density functional theory calculation. Moreover, receptor R1 and R2 show practical visible colorimetric test strip for the detection of fluoride, acetate, and carbonate ions. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimItem Design and synthesis new colorimetric receptors for naked-eye detection of biologically important fluoride and acetate anions in organic and arsenite in aqueous medium based on ICT mechanism: DFT study and test strip application(Elsevier B.V., 2020) Singh, A.; Mohan, M.; Trivedi, D.R.Novel three colorimetric anion receptors R1, R2 and R3 have been designed and synthesized via condensation reaction and characterized using IR, MS, and NMR spectroscopic techniques. Anion sensing properties were studied using colorimetric, UV–vis titration, 1H NMR titration, and Cyclic Voltammetric Studies. Comparing the UV–visible titration data of the receptors R1 and R2, R2 showed high redshift (??max) in the mixed competitive solution (DMSO: H2O, 9: 1; v/v) of about 155 nm, 157 nm, 169 nm for Na+F?, Na+AcO?, and Na+AsO2 ? ions with LOD of 0.23 ppm, 0.18 ppm, and 0.30 ppm, respectively. The observed spectral change of receptor R2 is due to the anion-induced deprotonation of the OH proton, which is confirmed by UV–vis titration, 1HNMR titration, and cyclic voltammetric studies. Theoretical studies via DFT calculation were carried for R1 and R2 to optimize the structure and to explain the anion-binding mechanism. The application of designed receptor R2 was successfully demonstrated for the detection of F? and AsO2 ? ions using a test strip. The receptors R1 and R2 proved itself to be potentially useful for real-life application by sensing F? and AcO? ions in real samples like toothpaste, mouthwash, vinegar and seawater in a complete aqueous medium. © 2019 Elsevier B.V.Item Design and synthesis of malonohydrazide based colorimetric receptors for discrimination of maleate over fumarate and detection of F?, AcO? and AsO2 ? ions(Elsevier B.V., 2020) Singh, A.; Mohan, M.; Trivedi, D.R.In this study, we have designed and synthesized two new organic receptors R1 and R2 based on malonohydrazide for the recognition of biologically important anions. The receptor R1 capable of colorimetric discrimination of maleate over fumarate ion, exhibit significant color change from pale yellow to wine red due to intermolecular hydrogen bond between the R1 and maleate ion, supported by 1HNMR titration, where the peak at ?12.0 ppm attributed to the NH proton experiences a downfield shift upon binding with maleate ion. Receptor R1, equipped with two electron-withdrawing [sbnd]NO2 moieties as the chromogenic signaling unit enhance the hydrogen bonding tendency and acidity, and thus when comparing with receptor R2, R1 displayed substantial higher redshift (??max) of 148 nm, 143 nm, and 140 nm towards F?, AcO?, and maleate anion in the DMSO. In addition, the synthesized receptors R1 and R2 are able to detect F?, AcO?, and AsO2 ? ions as their sodium salts in an aqueous solution with visual color change. Receptor R1 exhibit electrochemical response towards F? and AcO? ions. The receptors R1 and R2 are successfully applied for quantitative detection of F? ion in the toothpaste solution in an aqueous medium. Additionally, R1 and R2 exhibit fluorescence enhancement towards F? and AcO? ions in the DMSO. As well, R1 and R2 demonstrate to be potentially useful colorimetric chemosensor for sensing maleate ion using the test strip. The theoretical calculation based on TD-DFT corroborates well with the experimental results of the receptors R1 and R2 with fluoride, acetate and maleate. © 2019 Elsevier B.V.Item Spectroscopic studies of colorimetric receptors for detection of biologically important inorganic F?, AcO? and H2PO4 ? anions in organo-aqueous medium: Real-life application(Elsevier B.V., 2020) Singh, A.; Nishith, U.; Trivedi, D.R.Two new 4-nitrobenzylidene based receptors 2-((E)-(((E)-4-nitrobenzylidene) hydrazono) methyl)-1H-indole (R1) and 2-((E)-(((E)-4-nitrobenzylidene)hydrazono)methyl)-1H-pyrrole (R2) have been designed and synthesized by the simple condensation reaction and characterized by using spectroscopic techniques. The receptors exhibited high sensitivity and selectivity towards biologically important anions such as F?, AcO? and H2PO4 ? in DMSO and sodium salts F?, AcO? and H2PO4 ? in aqueous medium (9:1 v/v, DMSO: H2O). The receptors R1 and R2 dispensed high sensitivity towards sodium arsenite and detection limit were found to be 0.143 ppm and 0.32 ppm in (9:1 v/v, DMSO: H2O) reflect the stable complex formation of the receptor with AsO2 ? ion in aqueous medium. 1H NMR titration carried out to understand the nature of interaction between receptor R1 and F? ion. Cyclic voltammetric studies performed for receptors R1 and R2 in DMSO exhibited shift in oxidation and reduction peak with addition of basic F? ion signifying strong interaction between receptors and anions. Interesting, receptor R1 exhibited high selectivity for AcO? ion in the different range of pH from (6–11). Furthermore, receptor R1 and R2 showed colorimetric sensing of F? and AcO? ion present in commercially available toothpaste and vinegar in the form of Na+F? and Na+AcO? in aqueous medium. © 2020 Elsevier B.V.Item Utilization of lateritic soil stabilized with alkali solution and ground granulated blast furnace slag as a base course in flexible pavement construction(Springer, 2020) Amulya, A.; Ravi Shankar, A.U.; Singh, A.; Pammar, K.H.The natural aggregates are depleting in developing countries due to the excessive usage in road and building construction. In the present study, the engineering properties of abundantly available lateritic soil stabilized with Ground Granulated Blast Furnace Slag (GGBS) and alkali solutions like Sodium hydroxide and Sodium silicate was evaluated. The suitability of stabilized soil as a base course in flexible pavements was investigated. The lateritic soil was treated with 15, 20, 25 and 30% of GGBS and alkali solutions consisting of 5% of Sodium oxide with Silica Modulus (Ms) of 0.5, 1.0 and 1.5 at a constant water binder ratio of 0.25. The improved unconfined compressive strength, flexural strength, and fatigue life were observed from the soil treated with 30% of GGBS and alkali solution having Ms 1.0 air-cured for 28 days at ambient temperature. The improvement is due to the formation of Calcium Silicate Hydrates and Calcium Alumino Silicate Hydrates from an exothermic reaction between Calcium ions and the dissolved silicates and aluminates present in GGBS and alkali solutions. The samples treated with 25, 30% of GGBS and alkali solution having 1.0 Ms cured for 28 days found to be durable in Wetting-Drying and Freezing-Thawing tests. The compact and densified crystal orientation of the treated soil samples was observed from the microstructure images obtained from the Scanning Electron Microscope technique. The design of low and high volume roads was suggested with stabilized soil and strains developed at different locations on the proposed pavement were analyzed using pavement analysis software. © 2020, Chinese Society of Pavement Engineering. Production and hosting by Springer Nature.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.