Main-group porphyrins in artificial photosynthesis

Artificial photosynthesis is the mimicking of the natural photosynthetic energy conversion process using synthetic models. The associated study of these model is vital for understanding the intricate details of light absorption and the subsequent energy and electron transfer processes in natural photosynthesis. Most importantly, research in this area holds promise for technological advances in solar energy conversion and storage for future energy needs. Porphyrin molecules have emerged as logical candidates for the construction of artificial photosynthetic systems due to their similarities with natural photosensitizer chlorophyll molecules. Among the porphyrins, the main-group porphyrins hold a special place due to their unique structural, optical, and redox properties. This chapter reviews some of the recent developments in artificial photosynthesis using main-group porphyrins. First, a summary of the fundamental aspects, energy and electron transfer mechanisms and structural features relevant to artificial photosynthesis, is provided. Then, the synthetic models for the four major molecular components involved in the light reactions of oxygenic photosynthesis, (i) the light-harvesting antenna, (ii) the reaction center complex, (iii) the water splitting complex, and (iv) reductive catalysts, are examined. For each type of model, the design principles and mechanistic details are discussed using selected examples. Finally, the prospects of main-group porphyrins in artificial photosynthesis are argued.