Mechanistic Process Understanding of the Biomimetic Construction of Porphyrin-Based Light-Capturing Antennas from Self-Assembled Fmoc-Blocked Peptide Templates

Natural photosynthesis provides a perfect example of solar energy utilization that converts CO2 to carbohydrates at high efficiency. Herein, an innovative approach was developed to construct light-harvesting antennas via the precise control of porphyrin aggregation and platinum organization on the surface of the self-assembled structures of Fmoc-blocked peptides (Fmoc-ChaChaGK-NH2 and Fmoc-FFGK-NH2). The photophysical properties and the photocatalytic activity of the antenna are dependent on the aggregating structure of porphyrin and arrangement of Pt nanoparticles, which are related closely to the molecular structure of peptides, as well as to the peptide/porphyrin molar ratio and their concentrations. The Fmoc-ChaChaGK/porphyrin complexes prepared at a peptide (Fmoc-ChaChaGK)/TPPS molar ratio of 2 and TPPS concentration of 500 μM possess the highest photo-to-electric conversion efficiency and photocatalytic ability in transforming light energy into chemical energy and storing in the energy-storage molecules (reduced nicotinamide adenine dinucleotide, NADH). The results demonstrate the correlation between the hierarchical structure and light-responsive properties of the antenna and highlight the mediating effect of noncovalent interactions in the construction and stabilization of the photoresponsive materials.