Two-Dimensional Silver-Alkynyl Framework Based on Tetraalkynylporphyrin for Visible-Light-Driven Photocatalysis

The rational construction of crystalline two-dimensional metal–organic frameworks (2D MOFs) sustained exclusively by metal–carbon (M–C) bonds remains a significant challenge. Herein, we report a 2D silver-alkynyl framework, Ag-Por-MOF, assembled at room temperature from 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin (H2-TEPP) and silver(I) triflate (AgOTf). The material adopts a layered structure built from tetranuclear silver clusters bridged by Ag–C≡C linkages, with charge neutrality achieved without additional counterions, as supported by Ag K-edge XAS/EXAFS analysis, elemental analysis, and theoretical simulation. The framework exhibits broad visible-light absorption, pronounced photoinduced charge separation, and pronounced reactive oxygen species (ROS) generation capability under ambient illumination. The synthesis is readily scalable to the gram level without loss of crystallinity or porosity. As a heterogeneous photocatalyst, Ag-Por-MOF enables visible-light-driven oxidative cyclization of o-phenylenediamines and aldehydes to afford 2-substituted benzimidazoles with high efficiency (up to 97% yield), excellent functional-group tolerance, and robust recyclability over five consecutive cycles. This work provides a viable route toward M–C bond-based 2D frameworks for sustainable photocatalysis.