Robust Zn(II)-MOFs Built from Triphenylamine and Thiazolo[5,4- d ]thiazole Motifs for Photopromoted CO 2 Cycloaddition under Mild Conditions

The immobilization of photoresponsive motifs in metal-organic frameworks (MOFs) through a mixed-ligand strategy may provide more possibilities for optimizing functions such as catalysis, adsorption, and others. In this work, a novel complex {[Zn₂(tcppda)(DPTzTz)₂]·3DMF} (MOF-1) is obtained by assembling photoactive ligands 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole (DPTzTz) and N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine (H₄tcppda) under solvothermal conditions. MOF-1 possesses a 2-fold interpenetrated pillar-layered framework with open channels. The channel walls are decorated with high-density Lewis acidic Zn(II) centers and photoactive Lewis basic groups. The title MOF exhibits excellent thermal and chemical stability. The activated sample (MOF-1a) with permanent porosity exhibits photopromoted catalytic activity in the cycloaddition of CO₂ with epoxides under mild conditions. A reaction mechanism involving photogenerated electrons and holes is proposed to explain this enhancement. Furthermore, MOF-1a retains its structural integrity and catalytic performance over five consecutive recycling runs. This work establishes that the photoactive structural motif is critical for driving CO₂ cycloaddition under ambient-relevant conditions.