Ph.D Theses

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Browsing Ph.D Theses by Subject "Chemistry"

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    Inverse Electron Demand Diels Alder Reaction of Pyrido[1,2-a]pyrimidine 2-ones - Experimental and Theoretical Investigation and Antibacterial Activity of Synthesized Adducts
    (2023-03) Abinaya A; Dr. V.Sharulatha
    The IEDDA reaction of diene 2-oxo-2H-pyrido[1,2-a] pyrimidin-3(4H)-ylidiene acetic acid with various electron rich dienophiles in DMF medium yielded moderate to good yields in the presence of Lewis acid catalyst indium (III) chloride. FT-IR, 1H NMR, 13C NMR, and Mass Spectroscopy investigations were used to characterize and confirm the structures of all the synthesized adducts. Except for 3-butoxy-9-methyl-2,3,4,5 tetrahydropyrano[2,3-d]pyrido[1,2-a]pyrimidine-4-carboxylic acid (5) and Methyl-2-Oxo-1 Phenyl-1,2,3,3a,4,5-hexa hydropyrazolo[1,5-b]Pyrido[1',2':1,2]Pyrimido[5,4 e][1,2]Oxazine-4-Carboxylic Acid (7) which showed 1:1 and 6:4 ratio and for other adducts the ratio was found to be 6:1, supporting the endo rule. The analysis of the LUMO and HOMO energies of diene and dienophiles helped to prove the IEDDA reaction pathway. NBO charges computed using DFT techniques gave justification for the regioselectivity provided by the reaction. The synchronous nature of the transition states and intrinsic reaction coordinates of the reaction of diene 2-oxo-2H-pyrido[1,2-a] pyrimidin-3(4H) ylidiene acetic acid with dienophiles butyl vinyl ether and 1-methyl-1-cyclohexene by DFT method explained the observed diastereoisomeric ratio of 1:1 and 6:1 endo and exo ratio respectively. All synthesized compounds were tested for antibacterial activity, which showed moderate activity, however the compound 3a-methyl 2-oxo-1-phenyl-1,2,3,3a,4,5-hexahydropyrazolo[1,5-b]pyrido[1',2':1,2]pyrimido[5,4 e][1,2]oxazine-4-carboxylic acid was shown to be more powerful in both in-silico and in vitro investigations.
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    Investigation of Biomass Derived Functional Carbon Electrodes from leaves of Spathodea campanulata and Tecoma capensis for Supercapacitor applications
    (Avinashilingam, 2024-09) Tharani S; Guide - Dr. A. Prithiba
    This dissertation explores the process of synthesis, characterization and application of the relative biomass carbonaceous materials obtained from the ‘Spathodea campanulata and Tecoma capensis’ plants; more specifically, the effect of nitrogen doping particularly in improving its properties for use in supercapacitor applications is outlined in details. The choice to use biomass-based carbon materials is increasing due to the fact that such materials are sustainable and environment friendly. For this research, leaves of Spathodea campanulata and Tecoma capensis were selected as biomass precursors due to the fact that they are readily available. The preparation method included pyrolysis of the biomass and nitrogen doping with urea as the nitrogen source. All obtained Carbon / nitrogen-doped carbon materials were subjected to physicochemical characterizations includes FT-IR, XRD, Raman, BET, FESEM, EDAX, TEM to determine their structural and morphological properties The electrochemical performance of the carbon materials/ nitrogen-doped carbons has been analyzed. It was observed that nitrogen doping has enhanced capacitive behavior of the carbon materials. The nitrogen-doped carbons derived from Spathodea campanulata and Tecoma capensis exhibited high specific capacitance indicating their suitability as supercapacitor electrodes. This study highlights the potential of utilizing abundant biomass sources for developing high-performance supercapacitor materials through nitrogen doping, offering a sustainable approach to energy storage that aligns with green chemistry and renewable energy principle.
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    Synthesis, Computational Assessment and Biological Evaluation of 2-Amino-1,3,4-thiadiazoles and their Azo Derivatives
    (Avinashilingam, 2024-09) Kiruthika S; Dr. V. Sharulatha
    The development of new series of heterocycles has continued to support the growth of organic chemistry and pharmaceutical industry. The expansion of new and potent bio-active nitrogen and sulfur containing heterocycles was a constant requirement in the pharmaceutical industry. A search for potent anti-bacterial agents provoked us to design and synthesis 2-amino-1,3,4-thiadiazoles and their azo derivatives. The 2-amino-1,3,4-thiadiazoles were synthesized from eight different heterocyclic acids and thiosemicarbazide using concentrated sulphuric acid, p-toluene sulphonic acid and silica supported sulphuric acid catalysts. Silica supported catalyst yielded higher amount than other two catalysts. Amino group of thiadiazoles were converted into azo group by two couplers viz resorcinol and β-naphthol via conventional method resulting in excellent yields. Synthesized compound’s structures were elucidated by FTIR, UV-visible, 1H NMR, 13C NMR, mass spectroscopy and elemental analysis. DFT calculations were used to divulge the geometry optimization, quantum chemical descriptors, molecular electrostatic potential map and NBO analysis. Molecular docking analysis were performed against two proteins namely AgrA LytTR Domain of Staphylococcus aureus and LasR-TP1 complex of Pseudomonas aeruginosa. The highest docking score was found for compounds substituted with quinoline and β-naphthol rings. According to the in silico ADMET analysis all the compounds showed a good drug likeness property. The anti-bacterial activity was screened against Staphylococcus aureus and Pseudomonas aeruginosa. The target compounds with quinoline and β-naphthol substitution showed significant inhibitory activities against both the tested organisms than others. Moreover, these compounds exposed a correlation between experimental and theoretical predictions. The study provides basis for further in vivo and clinical trials of anti-bacterial activity.