A promising strategy to construct strong sensitizing iridium(III) complexes via energy transfer sensitization for continuous gram-level photosynthesis

Rational construction of strong sensitizing transition complexes is crucial for efficient artificial photosynthesis. Herein, we reported a promising strategy to develop strong sensitizing Ir(III) complexes (Ir-3 and Ir-4) by coupling visible-light-absorbing antennas with 1,8-naphthalenebenzimidizole based Ir(III) molecular platform via energy transfer sensitization. Impressively, the rate for photo-oxidation of dihydroxynaphthalene with Ir-4 can reach 202.0 × 10⁻³ min⁻¹, over 26 times faster than that with the typical [Ir(ppy)₂(bpy)]⁺. Furthermore, Ir-4 exhibits an outstanding catalytic activity in the photo-oxidative coupling of benzylamines with a yield of 92.6 %, over 9 times higher than that with [Ir(ppy)₂(bpy)]⁺. Systematical investigations reveal that the outstanding catalytic ability of Ir-4 could be attributed to its strong visible absorption, long-excited state lifetime, dual sensitizing sites and perfect multiple synergism among components. Notably, such a novel sensitizer was firstly assembled with SiO₂ to fabricate Ir-4@SiO₂ composites in bulk for continuous gram-level photosynthesis. These findings pave the way to rationally develop strong visible-light-absorbing multicomponent arrays on molecular level for large scale solar energy utilization.