Browsing by Author "Trivedi, D."

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Bithiophene based red light emitting material - Photophysical and DFT studies
(American Institute of Physics Inc. subs@aip.org, 2019) Mohan, M.; Satyanarayan, M.N.; Trivedi, D.
Bithiophene based red fluorescent light emitting material BTCN has been synthesized by Schiff base condensation reaction and characterized by standard spectroscopic techniques. The effect of -CN substituted amino pyrazole unit covalently linked to bithiophene moiety enhances the emission intensity in the system. In solid state BTCN exhibits an emission wavelength of 651nm with 170nm FWHM. Cyclic voltammogram shows the HOMO energy level of the BTCN to be -5.59 eV with LUMO around -3.24 eV. DFT optimized geometry of BTCN possesses a high amount of planarity in their structure and TD-DFT estimates the nature of electronic transitions occurring in the system. Overall, BTCN can act as good red light emitting material for organic light emitting applications. Â© 2019 Author(s).
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, Weinheim
Exploring the possibilities of double proton transfer in hydrazides: A theoretical approach
(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2019) Mohan, M.; Satyanarayan, M.N.; Trivedi, D.
Hydrazides are known to exhibit keto-enol tautomerism upon photoexcitation. Theoretical aspects uncovering excited state intramolecular proton transfer (ESIPT) of N-acylsubstituted hydrazides with bithiophene core have been investigated. Geometrical aspects of the system are expected to undergo double proton translocation at its excited state. However, potential energy surface study for all the molecules reveals an impossible concurrent double proton translocation and to a greater extent dubious step-wise double proton translocation in the system. Potential energy scans reveal molecules possessing a lower forward barrier at its excited state in comparison with their ground state suggestive of possible excited state single proton transfer. Geometrical attributes and spectral analysis suggest the strengthening of intramolecular hydrogen bond (N?H???O) at its excited state, favoring single proton translocation. Theoretical estimation of electronic energy transition for all the conformers yields good correlation with the experimental figures with an energy overestimation <0.17 eV. © 2019 John Wiley & Sons, Ltd.
Functionalized pyrene-based AIEgens: synthesis, photophysical characterization and density functional theory studies
(John Wiley and Sons Ltd, 2019) Mohan, M.; James, J.; Satyanarayan, M.N.; Trivedi, D.
Three new pyrene-based derivatives P1, P2 and P3 with a substituted pyrazole were designed, synthesized and characterized using standard spectroscopic techniques. Ultraviolet–visible (UV–vis) spectroscopic studies for P1–P3 uncovered a finite bathochromic shift of the molecules in solvents of varying polarity. Photoluminescence (PL) studies revealed the significant fluorescence emission of all molecules in higher polar solvents such as MeOH and dimethylformamide (DMF). Fluorescence quantum yield studies demonstrated the importance of P3 possessing cyanofunctionality for imparting higher emission with a quantum yield of 0.36%. Ratiometric studies performed in a tetrahydrofuran (THF)/H2O mixture indicated fluorescence enhancement with increasing overall percentage of water, confirming the aggregation-induced emission effect. Cyclic voltammetry study of molecules P1–P3 revealed an irreversible oxidation peak and the band gaps were calculated to be 2.26 eV for P1 and 2.31 eV for P2 and P3 respectively. Density functional theory (DFT) studies performed on molecules P1–P3 validate the structure correlation of the molecules. Theoretically estimated highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and bandgap correlated well with the experimental values. Furthermore, time-dependent (TD)DFT showed that the major contribution for the electronic transitions occurring in the system was governed by HOMO-1 and LUMO+1 orbitals. © 2019 John Wiley & Sons, Ltd.
Hg 2+ induced hydrolysis of thiazole amine based Schiff base: Colorimetric and fluorogenic chemodosimeter for Hg 2+ ions in an aqueous medium
(Elsevier B.V., 2019) Tekuri, V.; Sahoo, S.K.; Trivedi, D.
Simple pyrene-based chemosensors 1 to 3, were synthesized from pyrene-1-carboxaldehyde and they were characterized using various spectroscopic techniques like UV–Vis, FT-IR, Mass, 1 H NMR and 13 C NMR. Among synthesized receptors, the receptor 1 shows high selectivity towards Hg 2+ ions. Further, the high selectivity of receptor 1 towards Hg 2+ ions in the presence of various other interfering metal ions like Ni 2+ , Zn 2+ , Mn 2+ , Co 2+ , Cu 2+ , Cr 3+ , Fe 3+ , Al 3+ , Ag + , Fe 2+ , Cd 2+ , Mg 2+ , Pb 2+ , Ca 2+ , Na + , K + was confirmed by UV–Vis and fluorescence methods. The detection limit for Hg 2+ ions was found to be 0.270 ?M. The chemodosimetric irreversible hydrolysis of the receptor 1 in the presence of Hg 2+ was studied by UV/Vis, fluorescence, FT-IR, LC-MS, 1 H NMR and theoretical DFT study. Further, the real life applications of receptor 1 for the determination of Hg 2+ ions were demonstrated by UV–Vis method. © 2019 Elsevier B.V.
Screening of chitin deacetylase producing microbes from marine source using a novel receptor on agar plate
(Elsevier B.V., 2019) Pawaskar, G.-M.; Pangannaya, S.; Raval, K.; Trivedi, D.; Raval, R.
Chitosan is a deacetylated form of naturally occurring polymer; chitin. On an industrial scale, the deacetylation of chitin to chitosan is performed using harsh chemicals like sodium hydroxide. This not only adds to the environmental pollution but the product is also random in terms of its deacetylation. This shortcoming can be addressed by using enzymes like chitin deacetylase (CDA). The screening of these organisms would require a reliable, fast and sensitive screening method. The deacetylation of chitin into chitosan, releases acetate as the byproduct of the reaction. A receptor which specifically binds to the acetate ion was synthesized chemically. The receptor upon binding with the acetate ion emitted a fluorescence which could be viewed using the gel documentation unit. The receptor was optimized for the screening of CDA producing microbes with the positive fungal control as Penicillium sp. and bacterial control as Bacillus megaterium. A parallel study with the 4-Nitroacetanilide, the reported screening indicator for CDA was performed. The results obtained with the receptor in the present study were concordant with the 4-Nitroacetanilide. Upon standardization, the protocol was extended for the screening of CDA producing microbes from the marine crustacean dumped soil and water samples. The CDA activity of these microbes was further confirmed using spectrophotometric MBTH assay. This is the first report using this receptor for the screening of CDA producers. The method is not only sensitive but also reproducible and can be extended for a high throughput screening of CDA producers. © 2019 Elsevier B.V.
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.