Photocatalysis has increasingly become a major focus as a sustainable pathway for chemical reactions with visible light photocatalysts performing a large range of reactions such as redox reactions, cyclization reactions, and energy transfer reactions. Silicon phthalocyanines (SiPcs) have been largely ignored as photosensitizers in photocatalytic reactions, despite their low energy excitation, long triplet lifetimes, and their ability to form singlet oxygen. By incorporating alkyl, aryl, and silicon protecting groups as axial ligands on the silicon center, three SiPcs have been generated by the Wiskur research group with the goal of developing three novel photocatalysts for organic synthesis. Using cyclic voltammetry and Stern Volmer quenching studies, we have shown SiPcs are capable of exchanging electrons with appropriate substrates, including Hünig’s base and dimethylaniline (DMA) with varying redox potentials. We have also successfully used a SiPc catalyst in a reductive quenching reaction where Hünig’s base served as a sacrificial electron donor in the reaction. In addition to being redox-active, our preliminary data also shows SiPcs are capable of performing energy transfer reactions, by performing a reaction that utilizes singlet oxygen as a reactant under visible light conditons. This reaction, in combination with cyclic voltammetry studies, has also served as a model to understand how axial substitution on the silicon center seems to influence the photostability of these species. These results, as well as the photophysical and electrochemical experiments for each SiPc, will be presented.<br/>

Exploration of silicon phthalocyanines as viable photocatalysts for organic transformations

ACS Fall 2020 Virtual Meeting

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