Faculty Publications
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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 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 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.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 Design and development of TiO2 coated microflow reactor for photocatalytic partial oxidation of benzyl alcohol(Elsevier B.V., 2020) Pradhan, S.R.; Nair, V.; Giannakoudakis, D.A.; Lisovytskiy, D.; Colmenares, J.C.The synthesis of valuable organic compounds from naturally available and renewable biomass is an open field of research towards adaptation in real-life applications. Photocatalytic valorization is assumed as a potential candidate, although the lower efficiency of the traditional batch photocatalytic reactor sets some drawbacks. Recently, photocatalytic microreactors revealed as a prosperous candidate for various photocatalytic reactions, especially for selective oxidation. This area of research is challenging due to the development of the proper photocatalytic microreactor for the targeted application. Deposition of the catalyst on the internal surface of the microreactor, the sufficient utilization of the irradiation, optimization of the reaction parameters are among the most vital parameters that should be considered upon the design. Although, to obtain the most active material and tune its crucial features to maximize its catalytic performance inside the microreactors is the uppermost important part. This work introduces ultrasound-assisted TiO2 deposition on the inner walls of a perfluoroalkoxyalkane microtube under mild conditions. The deposition experiments were carried out with commercial and sol-gel synthesized TiO2. The materials were characterized by XRD, UV–vis DRS, Scanning Electron Microscopy (SEM), and nitrogen sorption. The photocatalytic activities of the TiO2 nano-engineered fluoropolymer based microreactors were evaluated for the oxidation of benzyl alcohol in flow. © 2020 The Author(s)