Research Projects

Catalysis plays a crucial role in energy production and is involved in critical processes such as H₂O₂ generation, plastic degradation, and drug synthesis.¹ However, most catalytic processes use toxic and expensive heavy transition metals such as Pt, Ru, Ir, etc.²-³ Thus, extensive use of noble metals for energy production, including catalysis, has jeopardised their natural abundance.⁴ Therefore, catalytic processes based on earth-abundant elements would provide a benign alternative. Recently, supramolecular catalysis has gained substantial attention due to its controlled chemical reactivity induced by the microenvironment. These systems can mimic enzymatic activity, thus enhancing the rate by 10⁵-fold in comparison with traditional homogeneous catalysts.⁵ The molecular cages are synthesized by covalent bonds, hydrogen bonds, or by metal-ligand interactions thus these structures are either a) porous organic cages or b) metal-organic cages.⁶ These cages possess cavities of varied shapes, non-bonding interactions, essential for stabilisation of active species, and are explored in pore-induced selective catalysis.⁷ Despite such traits, their application as redox catalysts is limited. The rationale for the limited progress of organic cages towards redox catalysis may be attributed to the use of simpler, redox-innocent linkers.⁸ Therefore, the design of organic cages based on redox non-innocent linkers would enhance the reactivity of these cages towards enabling redox catalysis. In this context, the phenalenyl (PLY) molecule, a class of odd alternant hydrocarbons, holds a vacant non-bonding molecular orbital that can host electrons without disrupting the aromaticity. Thus, PLY molecules exist in three redox states: the closed-shell cation (12π e-), open-shell mono-reduced neutral radical (13π e-), and in a closed-shell doubly reduced anion (14π e-), without complete disruption of aromaticity.⁹ Interestingly, using the single electron transfer possibility in PLY-based scaffold, Mandal et al. (the proposed host of the project) reported PLY-mediated activation of aryl halide, facilitating metal-free cross-coupling reactions at room temperature.¹⁰,¹¹ Whereas on photoexcitation, PLY undergoes substrate-dependent redox cycles, facilitating coupling reactions, atom-transfer catalysis, and gas activation.¹²-¹⁴ Thus, cages based on PLY motifs can be an ideal building block for studying the transition metal-free redox catalysis. We thus propose to design a PLY-based redox cage via functionalization and complexation with earth-abundant main group elements such as boron and aluminium. The possibility of modifying the properties of these cages provides fine-tuning of their catalytic activity, offering avenues for designing efficient and selective catalysis. Thus, employing PLY-based redox cages as catalysts in forming new C–C, C–O, and C–N bonds would render the research proposal of great significance in industrial as well as academic domains.