Enhanced Solar Energy Harvest and Electron Transfer through Intra- and Intermolecular Dual Channels in Chlorosome-Mimicking Supramolecular Self-Assemblies

The direct connection between a photosensitizer and an electron mediator, achieved by a precise arrangement based on chlorosome, provides photosynthetic bacteria the maximum efficiency in solar energy conversion. Herein, this study reports the fabrication of a biomimicking chlorosome for biocatalyzed artificial photosynthesis through self-assembly of simple molecules to functional systems. TCPP/EYx/Rh8–x macromolecules, synthesized through a sequential amidation reaction of porphyrin (TCPP), eosin Y (EY), and [Cp*RhCl2]2, were found to self-assemble into chlorosome-mimicking supramolecular assemblies through noncovalent interactions. Intra- and intermolecular dual channels for enhancing electron transfer were constructed in TCPP/EYx/Rh8–x supramolecular assemblies. In addition, the energy band structure of TCPP/EY4/Rh4 supramolecular assemblies also made a perfect coordination with oxidation and reduction potentials of an electron donor and NAD+, which led to a fast and oriented electron transfer along the electron donor, TCPP/EY4/Rh4 and NAD+. In comparison with a system using free components, the yield of NADH photoregeneration was improved from 15% to 91% by TCPP/EY4/Rh4 supramolecular assemblies; when this NADH photoregeneration process was coupled with dehydrogenases, 38 μM methanol was synthesized from CO2 after 2 h of visible light irradiation, which was about 12-fold higher than that obtained using free components. The chlorosome-inspired TCPP/EYx/Rh8–x supramolecular assemblies with intra- and intermolecular electron transfer dual channels represents a landmark for implementing highly effective solar energy conversion and selective methanol synthesis from CO2 in a green and sustainable manner.