Executive Summary : | This project focuses on designing, synthesizing, and characterizing heteroleptic binuclear metal complexes supported by tetradentate spectator ligands and bridged by noninnocent ligands to develop molecule-based magnetic materials and investigate the chemistry of biomimetic water oxidation. The project will prepare tetradentate facially coordinating supporting ligands L1, HL2[R1,R2], H2L3[R1,R2], L4 and H2L5[R1,R2], tridentate L4 and H2L5[R1,R2], and redox-active bridging ligands LB1, H4LB2 and H4LB3. The tetradentate supporting ligands (L) and bridging noninnocent ligands (LB) will be used to prepare binuclear heteroleptic metal complexes (L)M‒LB‒M(L) to develop magnetic materials. spin crossover (sCO) behaviors are expected in these hypothetical complexes by tuning sufficient ligand-field strength through changing bridging and supporting ligands. Ligand-centered radicals will be produced into these heteroleptic complexes through exposure to atmospheric oxygen or using appropriate oxidizing or reducing chemicals as external reagents. The project also aims to develop metal complex-based homogeneous catalysts for water oxidation (WOC) employing noninnocent ligands via metal-ligand cooperativity. The goal is to prepare efficient and robust water oxidation electrocatalyst using earth-abundant, inexpensive first-row transition metal ions supported by redox noninnocent bridging ligands. The tridentate spectator ligand (L) will be used to prevent the decomposition of the catalyst, while redox-active bridging ligands (LB) have the ability to undergo reversible oxidation, making it easier to access metals in their high oxidation states and remove the four electrons needed for the water oxidation reaction. The effect of various supports on the efficiency and reaction mechanism of the catalyst will also be investigated. |