Luminescent Re(I) and Ir(III) Complexes for Photocatalytic Organic Transformations and Surface Modifications

Building on the phosphorescent properties of recently synthesized isocyano Re(I) diimine complexes, we have developed a novel series of isocyanoborato complexes that exhibit intense phosphorescence, making them promising candidates for electroluminescent device applications. Beyond their potential as emissive materials, these complexes have also shown excellent performance as photocatalysts and photosensitizers. To enhance stability and efficiency in photocatalysis, we introduced a new class of phosphorescent Re(I) carbene complexes. Unlike tricarbonyl Re(I) diimine complexes, which require UV light for CO₂ reduction, Re(I) isocyanide and carbene complexes utilize visible light for this process.

Beyond CO₂ reduction, we will present our work on photoredox catalysis in organic transformations, particularly in fluorinated alkyl halide activation. This exploits the triplet excited states of Re(I) and cyclometalated Ir(III) complexes. To improve practical applications, we have designed recyclable solid-supported photocatalysts by immobilizing these transition metal complexes on solid substrates. Emission quenching studies were conducted to evaluate bimolecular electron transfer processes between the excited states of these immobilized complexes and solution-phase substrates. We also established a correlation between electron transfer efficiency and catalytic performance, providing insights into designing robust, efficient and recyclable heterogeneous photoredox catalysts. Given the efficacy of certain solid-supported photocatalysts in photoredox catalysis, we will also discuss their successful application in the chemical modification of materials to introduce functional properties.