Highly effective solar CO2 fixation via photocatalytic carboxylation of aromatic amines with carbon dioxide over a covalent organic framework (COF) as a photocatalyst†

Carbon dioxide (CO₂) is an attractive building block in terms of abundance and sustainability. However, the low reactivity of CO₂ limits its application in organic reactions as frequently high-energy reagents are needed to drive organic transformation. Here, we report the efficient carboxylation of aromatic amines with CO₂ in the presence of a covalent organic framework (COF) as a photocatalyst in combination with a nickel(II) complex as a co-catalyst under solar light irradiation. This solar-light photo-catalyzed strategy provides a facile method to produce a series of valuable carboxylic acids. Moreover, this versatile protocol shows an inexpensive photocatalyst, mild reaction conditions, and good functional group tolerance without the necessity of using stoichiometric metallic reductants. Moderate to good yields of the desired carboxylic acids were obtained in a substrate scope. This method opens new opportunities for the carboxylation of aromatic amines with CO₂.