Two Carbazolic Cage-Type MOFs for Photocatalytic Oxidative Coupling of Thiols to Disulfides.

In this paper, two isostructural cage-type metal-organic frameworks LCU-601(M = Mn2Ti or Al) were synthesized by using the photosensitive carbazole-based carboxylic acid ligand H4PBCD and a presynthesized [Mn2Ti(μ3-O)(CF3COO)6] cluster or in situ generated [Al3(μ3-O)(COO)6] cluster, respectively. Particularly, LCU-601(Al) exhibits excellent structural stability, permanent porosity for N2 and CO2 adsorption, and photoresponsive performance. This material serves as an efficient heterogeneous photocatalyst for the oxidative coupling of thiols into disulfides under mild conditions (room temperature and 1 atm O2) and demonstrates good recyclability and structural integrity during consecutive catalytic cycles. Mechanism studies unveil that photogenerated holes (h+) and superoxide radicals (O2•-) are the crucial active species for the photocatalytic S-S bond formation.