A multifunctional bismuth-based metal–organic framework with record-high porosity, rare topology, and efficient visible light photocatalysis

Abstract

Here, we report the bismuth-based metal–organic framework (MOF), UU-206, constructed from Bi(NO₃)₃·5H₂O and an extended tetraphenylenethylene-cored octacarboxylate linker (H₈ettb). UU-206 crystallizes as a three-dimensional framework that can be described by the rare msg/wxs nets and features four one-dimensional channels with pore diameters of approximately 6–11 Å. Nitrogen sorption isotherms at −196 °C reveal a Brunauer–Emmett–Teller (BET) surface area of 1119 m² g⁻¹ and a total pore volume of 0.55 cm³ g⁻¹, placing UU-206 among the most porous Bi-MOFs reported to-date. Optical and electrochemical measurements show that the material is a visible light responsive semiconductor (E_g ≈ 2.68 eV) with efficient photoinduced charge separation. Consequently, UU-206 functions as an efficient heterogeneous photocatalyst for the aerobic oxidative condensation of amines to imines, delivering up to 86% yield under visible light irradiation and outperforming related Bi-based materials. Notably, the reaction can also be driven by low-intensity natural sunlight at high latitudes, underscoring the potential of UU-206 as a platform for solar-driven organic transformations. Furthermore, this work demonstrates how integrating polytopic chromophore linkers with Bi-cluster nodes provides a powerful design strategy for developing multifunctional MOFs with high porosity, rare topology, and efficient visible light photocatalysis.