Hydrogen Evolution of a Unique DNAzyme Composed of Cobalt-Protoporphyrin IX and G-Quadruplex DNA

Molecular hydrogen (H₂ ) is a clean and renewable fuel that has garnered significant interest in the search for alternatives to fossil fuels. Here, we constructed an artificial DNAzyme composed of cobalt-protoporphyrin IX (CoPP) and G-quadruplex DNA, possessing a unique H₂ O_int ligand between the CoPP and G-quartet planes. We show for the first time that CoPP-DNAzyme catalyzes photo-induced H₂ production under anaerobic conditions with a turnover number (TON) of 1229 ± 51 over 12 h at pH 6.05 and 10 °C. Compared with free-CoPP, complexation with G-quadruplex DNA resulted in a 4.7-fold increase in H₂ production activity. The TON of the CoPP-DNAzyme revealed an optimal acid-base equilibrium with a pK_a value of 7.60 ± 0.05, apparently originating from the equilibrium between Co(III)-H^- and Co(I) states. Our results demonstrate that the H₂ O_int ligand can augment and modulate the intrinsic catalytic activity of H₂ production catalysts. These systems pave the way to using DNAzymes for H₂ evolution in the direct conversion of solar energy to H₂ from water.