Diverse Photochemical Activation Modes Enabling Efficient Functionalization of Organic Molecules

Azim, Aznur (2026) Diverse Photochemical Activation Modes Enabling Efficient Functionalization of Organic Molecules. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Aznur Azim (20RS032)) 20RS032.pdf Restricted to Repository staff only Download (29MB)

Abstract

The thesis entitled ‘Diverse Photochemical Activation Modes Enabling Efficient Functionalization of Organic Molecules’ is divided into five chapters, each reflecting the results of the experimental work conducted throughout the five-year duration of my research. This thesis explores multiple photochemical activation pathways to achieve efficient and selective functionalization of organic molecules. The work integrates photoredox catalysis, ligand-to-metal charge transfer (LMCT), electron donor-acceptor (EDA) complex activation, and energy-transfer processes. Each activation mode was systematically applied to construct and modify nitrogen-based heterocycles and other valuable molecular frameworks. Visible-light-driven methods were employed to enable transformations under mild, environmentally friendly conditions. The strategies developed avoid the use of harsh reagents and minimize the generation of toxic by-products. Mechanistic investigations were carried out to understand the reactive intermediates and pathways involved. The combined use of different activation modes allowed access to transformations that were previously challenging or unfeasible. This approach highlights the versatility of photochemistry as a platform for modern synthetic organic chemistry. Overall, the work demonstrates that diverse photochemical modes can be harnessed to enable efficient, selective, and sustainable organic functionalization. Chapter 1 of this thesis provides a broad photochemical activation pathways and their utilisation in the functionalization of organic molecules. Chapter 2 presents a visible light-mediated, metal-free strategy for the efficient one-pot synthesis of N-aryl γ-lactams via a cascade radical addition-cyclization approach. In chapter 3 we disclose a visible-light-driven iron catalyzed LMCT approach for synthesizing indolo[2,1-a]isoquinolin-6(5H)-one scaffolds via a cascade radical addition-cyclization process. In chapter 4 we present a visible-light-induced, metal- and photocatalyst-free strategy for C-3 carbamoylation of quinoxalinones via EDA complex formation. In chapter 5 we report a visible-light-induced [2+2] cycloaddition between 2-methoxy naphthalene and maleimide, enabling the synthesis of structurally diverse cyclobutane derivatives.

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