Electron transport chain-inspired coordination polymers for macroscopic spatiotemporal scales of charge separation and transport in photocatalysis.

ABSTRACT

Classic homogeneous photocatalysis is limited by the temporal transience and the spatial proximity of photoinduced charge separation and transport. The electron transfer chain (ETC) in cellular respiration can mediate unidirectional and long-range electron transfer to isolate the oxidation and reduction centres. Inspired by this, we modified electron-accepting (A) viologen with π-extending thiazolothiazole and electron-donating (D) phenyl carboxylate into a D-A-π-A-D-type ligand and assembled segregated dye stacking in coordination polymer Cd-TzBDP for breaking the spatiotemporal limitation of single-molecule photocatalysis. The offset characteristics of D-A segregated stacking not only allowed the photoinduced-2e- transfer from the D-type carboxylate terminal to the spatially adjacent A-type viologen motif within 1 ps but also permitted the following delocalization of e- and h+ along stacked columns. These advantages endowed Cd-TzBDP with long-lived photochromic visualization of intermittent aerobic photooxidation steps, which enabled the bioinspired ETC-mediated aerobic respiration of mitochondria, achieving the continuous photocatalytic α-C(sp3)-H functionalization of tertiary amines with pharmaceutical interest. Enlightened by ETC-mediated electron leak in hypoxia, the coordination polymer was further employed in a photocatalytic membrane reactor, which visually illustrated the photo-driven cross-membrane long-range transfers of multiple electrons and protons from the hypoxic compartment to normoxic one, benefiting the distal photooxidation and photoreduction with biomimetic compartment selectivity.