Sahu, Saugata2018-06-292023-10-192018-06-292023-10-192016ROLL NO.11612212https://gyan.iitg.ac.in/handle/123456789/1025Supervisor: G. KrishnamoorthyProton transfer is one of the fundamental reactions in many chemical and biological processes. In the above mentioned thesis, the intermolecular proton transfer, intramolecular proton transfer, excites state double proton transfer were investigated with different molecular systems. The studies revealed that how the proton transfer processes yielded different end products like different tautomer, anion, cation, zwitterion etc. The thesis also described molecular switches, binary subtraction, keypad lock system with simple cation anion interaction with different azole systems. The construction of fuzzy interference system is represented with an azole system to follow the stimuli response of the fluorophore. A brief description of the thesis work is presented below.The intermolecular proton transfer was studied between 2-(2'-hydroxyphenyl)benzimidazole (HPBI) and different anions. Despite the fact that HPBI exists as cis-enol (major) and trans- enol (minor) in neutral form, earlier it was reported to exist only in the trans-form upon deprotonation in aqueous medium. It was also stated that the dianion formed in the ground state was reprotonated to form the trans-anion in the excited state. In the current thesis, it was established that the cis-anion and dianion can be obtained upon proper stabilization. It was also demonstrated that the switching between cis- and trans- anion is possible. Theoretical calculations were also performed to substantiate the existence of cis-anion and dianion. In converse to the literature report, it was also proven that not only in protic solvents but also in aprotic solvents ‘OH’ group is deprotonated before the ‘NH’ group to form monoanion.enCHEMISTRYThesis