MOLECULAR COMPUTATIONS AND REACTIVITY STUDIES ON NITROGEN (N)-CONTAINING HETEROCYCLES

Nitrogen (N)-heterocycles are a class of organic compounds containing nitrogen atoms in their ring structures. At present, these heterocycles find diverse applications in several disciplines ranging from chemistry, biology to material science and beyond. Their versatile structural and fine-tunable electronic properties make them a fundamental building block for biomacromolecules^, natural products, drugs/drug-like molecules, catalysis, functionalized materials among many more This thesis explores the properties and reactivity of N-heterocycles in two key thrust areas: Molecular Computation and Chemical Reactivity, addressing fundamental challenges and proposing innovative solutions. The first thrust investigates N-heterocycles as molecular logic gates, which mimic digital logic operations in response to several chemical inputs. Existing molecular logic gates exhibit non-resettability and input grouping for structurally and chemically similar analytes like cysteine and homocysteine. Chapter 2 exploits an analyte-responsive oxazinoindoline-based fluorescent molecular logic gate network which achieves resettable analyte processing and successfully discriminates between cysteine and homocysteine, addressing critical limitations in thiol-based diagnostics. Chapter 3 expands the utility of molecular logic gates by developing a simplified interdisciplinary STEM education platform for teachers and students. This cost-effective course integrates disciplines such as organic chemistry, photochemistry, engineering, and computational chemistry. Our approach demonstrates how molecular logic gates can serve as versatile platforms for teaching fundamental and applied scientific concepts in modern-day classrooms and laboratory, making interdisciplinary learning accessible in resource-limited settings across the world. The second thrust investigates N-heterocycles from a standpoint of their chemical reactivity, focusing on the effect of substituents on their structural and electronic properties. Chapter 4 probes the unexpected reactivity of halogen-substituted pyrazoles under reductive reaction conditions, highlighting a non-intuitive mechanism for 4-bromo-pyrazolyl scaffold as compared to its 4-Iodo-pyrazolyl analogue. Experimental observations and computational predictions help understanding how subtle structural variations and reaction environments govern certain reaction transformations, providing detailed insights into synthetic strategies for halogenated heterocycles. In summary, this thesis demonstrates the immense potential of N-heterocycles in molecular computation and applied organic chemistry. Through a common theme of interdisciplinary innovation and mechanistic understanding, this thesis bridges several gaps in molecular computation, STEM learning and education, and synthetic chemistry, providing a foundation for future research in chemical and biological sciences.