Amino-substituted triazatriangulenium photosensitizers for CO2 capture and aminocarbonylation to amides

Efficient photoreduction of CO2 to CO using noble-metal-free systems remains a significant challenge in artificial photosynthesis. Developing low-cost photosensitizers capable of capturing CO2 and facilitating electron transfer is therefore essential. Here, we report an amino-substituted triazatriangulenium photosensitizer (A-TATA) that enables light harvesting and CO2 capture in a photocatalytic system. Systematic studies show that A-TATA, functionalized with free amino groups, captures CO2 as carbamic acid, serving as a local CO2 reservoir. This increased local concentration of CO2 lowers the onset potential of the cobalt catalyst. Notably, the system achieves a turnover number of 33,976 with 98% selectivity and an optimized quantum yield of 51% for CO−among the highest reported for molecular photocatalysis. Furthermore, the generated CO is converted into amides via aminocarbonylation, achieving 85% atomic efficiency and operating effectively even in the absence of solvent. These findings offer a strategy for designing versatile organic photosensitizers for sustainable CO2 capture and conversion.