Faculty Publications
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Item A simple, rapid and accurate complexometric method for the determination of palladium(II) is proposed, based on the selective demasking property of 2-mercapto propionyl glycine (MPGH2) towards palladium(II). In the presence of diverse metal ions, palladium(II) is complexed with excess of EDTA and the surplus EDTA is back titrated at pH 5-5.5 (acetic acid-acetate buffer) with standard zinc sulphate solution using xylenol orange as indicator. An excess of a 0.2% aqueous solution of MPGH2 is then added to displace EDTA from Pd(II)-EDTA complex. The released EDTA is titrated with the same standard zinc sulphate solution as before. Reproducible and accurate results are obtained in the concentration range 2-22 mg of palladium with relative error of ±0.36% and coefficient of variation (n=6) not exceeding 0.31%. The effect of diverse ions are studied. The method is used for the determination of palladium in its complexes, catalysts and synthetic alloy mixtures.(Complexometric determination of palladium(II) using 2-mercapto propionyl glycine as demasking agent) Shetty, P.; Nityananda Shetty, A.N.; Gadag, R.V.2002Item A simple, rapid, selective and sensitive spectrophotometric method for the determination of palladium is proposed using piperonal thiosemicarbazone (PATS) as a reagent. The reagent forms a 1:2 complex (Pd:Reagent) with palladium. The yellow complex is soluble in 32-40% ethanol and has an absorption maximum at 363 nm. Beer's law is obeyed upto 3.85 ppm of palladium and the optimum concentration range is 0.5-2.45 ppm of Pd. The molar absorptivity and Sandell's sensitivity are 3. 80 x 104 dm3 mol-1 cm -1 and 2.8 x 10-3 ?g cm-2, respectively. The experimental conditions for complete colour development and the interference from various ions are investigated. The method is used for the determination of palladium in its complexes and synthetic mixtures.(Spectrophotometric determination of palladium(II) using piperonal thiosemicarbazone) Shetty, P.; Nityananda Shetty, A.N.; Gadag, R.V.2003Item A simple, rapid and selective complexometric method is proposed for the determination of mercury(II) in the presence of associated metal ions. Mercury(II) is first complexed with an excess of EDTA and the surplus EDTA is titrated against standard zinc sulphate solution at pH 5-6 using xylenol orange indicator. Glutathione is then added to displace EDTA from the Hg-EDTA complex quantitatively and the EDTA released is back titrated against a standard zinc sulphate solution as before. The method works well in the range 4 to 80 mg of mercury with a relative error of less than 0.30% and a coefficient of variation of not more than 0.38%. The effect of the presence of various diverse ions has been studied. The method is used for the determination of mercury(II) in its alloys and complexes.(Rapid complexometric determination of mercury(II) using glutathione as a selective demasking reagent) Shetty, P.; Nityananda Shetty, A.N.2004Item Spectrophotometric determination of platinum(IV) in alloys, complexes, environmental, and pharmaceutical samples using 4-[N,N-(diethyl)amino] benzaldehyde thiosemicarbazone(2010) Naik, P.P.; Karthikeyan, J.; Nityananda Shetty, A.N.4-[N,N-(Diethyl)amino] benzaldehyde thiosemicarbazone (DEABT) is proposed as an analytical reagent for the spectrophotometric determination of platinum(IV). The DEABT forms 1:2 yellow complex with Pt(IV), which is sparingly soluble in water and completely soluble in water-ethanol-DMF medium. The Pt(IV)-DEABT complex shows maximum absorbance at 405 nm. Beer's law is valid up to 7.80 ?g cm-3, and optimum concentration range for the determination of platinum(IV) is 0.48-7.02 ?g cm-3. The molar absorptivity and Sandell's sensitivity of the method are found to be 1.755 × 104 dm3 mol-1 cm-1 and 0.0012 ?g cm-2, respectively. The relative error and coefficient of variation (n=6) for the method does not exceed ±0.43% and 0.35%, respectively. Since the method tolerates a number of metal ions commonly associated with platinum, it can be employed for the determination of platinum in environmental samples, pharmaceutical samples, alloys, catalysts, and complexes. The method is rapid as the Pt(IV)-DEABT complex is soluble in water-ethanol-DMF medium and not requiring any time consuming extraction method for the complex. © 2010 Springer Science+Business Media B.V.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 Colorimetric and fluorometric turn-on sensor for selective detection of fluoride ions: Sol-gel transition studies and theoretical insights(Royal Society of Chemistry, 2018) Pangannaya, S.; Mohan, M.; Trivedi, D.R.A new organic receptor R1 based on a naphthyl unit covalently linked to a long alkyl chain has been designed, synthesized and characterized by standard spectroscopic techniques. The colorimetric response of receptor R1 from colorless to a pale yellow color and blue fluorescence emission in the presence of F- ions revealed its selective sensing ability in the solution phase. UV-Vis titration, fluorescence titration and 1H NMR titration studies confirmed the formation of the R1-F- complex. Receptor R1 formed a stable gel in DMSO and was confirmed through the standard heating-and-cooling method. Addition of F- ions resulted in disruption of the gel forming a solution that exhibited blue fluorescence emission. The binding constant of the R1-F- complex was found to be of the order of 5.9 × 105 M-1. DFT studies revealed the formation of the receptor-anion complex agreeing well with the experimental results. The detection limit was calculated and found to be 0.8 ppm, implying the potential for application of receptor R1 in environmental applications. © 2018 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Evaluation of pyrolyzed areca husk as a potential adsorbent for the removal of Fe2+ ions from aqueous solutions(Academic Press, 2019) Sheeka Subramani, B.; Shrihari, S.; Manu, B.; BabuNarayan, K.S.[No abstract available]Item Theoretical insights into molecular mechanism and energy criteria of PARP-2 enzyme inhibition by benzimidazole analogues(John Wiley and Sons Inc, 2021) Venugopal, P.P.; Shilpa, M.; Chakraborty, D.The emergence of poly (ADP-ribose) polymerase (PARP) inhibitors targeting a class of PARP enzymes has gained a great interest in cancer therapy. Majority of the PARP inhibitors are not isoform-selective which may cause unwanted off-target effects. In the present study, we explore the molecular mechanism and energy requirements for PARP-2 inhibition. This involves docking studies, frontier molecular orbital analysis, 500 ns molecular dynamics simulation (MD), binding free energy analysis and principal component analysis. The results clearly suggest the importance of hydrogen bonding (Gly429, Gln332, Ser470, Tyr455) and ?-? stacking interactions (His428, Tyr455, Tyr462, Phe463, Tyr473) between residues and the inhibitor. Presence of lowest unoccupied molecular orbitals favors ?-? stacking interactions and highest occupied molecular orbital orbital favors hydrogen-bonding interactions in the ligands. The stability of most active/PARP-2 complex is confirmed by hydrogen bonding and ?-? stacking interaction parameters. Molecular-mechanics Poisson-Boltzmann surface area energy calculations showed that van der Waals and nonpolar solvation energy terms are crucial components for the stable binding of the ligands. Per residue analysis showed that tyrosine, histidine, and phenyl alanine residues are responsible for hydrophobic interactions with the ligands. Four new inhibitors are designed based on this study and the stability of PARP-2/inhibitor complex is validated by MD, density functional theory studies, and ADME/toxicity properties. Information from the present study can serve as a basis for designing new isoform-selective PARP-2 inhibitors. © 2021 Wiley Periodicals LLC.Item Developing a biocatalyst showcasing the synergistic effect of rice husk biochar and bacterial cells for the removal of heavy metals(Royal Society of Chemistry, 2023) Manikandan, S.K.; Nair, V.Heavy metals like cadmium (Cd) and nickel (Ni) are toxic pollutants that affect the environment and pose health risks. Removal of Cd and Ni through bioremediation in the presence of biochar is a sustainable strategy. This study investigated the removal of Cd and Ni by Pseudomonas stutzeri immobilized on rice husk biochar (PRHB). The removal efficiency was calculated by varying the culture incubation time, pH, temperature, biocatalyst dosage, and initial metal ion concentration. PRHB showed a maximum metal removal capacity of 95% Cd and 92% Ni. The removal efficiency of PRHB was higher than that of free cells, which could be attributed to simultaneous adsorption, ion exchange, complexation, precipitation, and bioaccumulation caused by the biochar carrier and bacteria. The rice husk biochar material served as both an adsorbent and a carrier supplying nutrients for the growth of the bacteria. Considering the excellent metal ion removal capability and reusability, the use of PRHB could be a promising, cost-effective, and environment-friendly strategy for treating wastewater containing heavy metals. © 2023 The Royal Society of Chemistry.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. © 2024