POROUS DOUBLE-WALLED METAL-TRIAZOLATE FRAMEWORK BASED UPON BI-FUNCTIONAL LIGAND AND PENTANUCLEAR ZINC CLUSTER EXHIBITING SELECTIVE CO2 UPTAKE

摘要

Metal-organic frameworks (MOFs) have been promoted into very promising candidates with potential applications in gas storage, separation, heterocatalysis, sensor and other areas, due to their intriguing topologies and structural tunability. Recently there is an escalating interest in utilizing azolate-based ligands such as pyrazolate, 1,2,4-triazolate, 1,2,3-triazolate, and tetrazolate, to generate functional MOFs with surface featuring exposed sites for various applications. Among those, 1,2,3-triazolate-based ligands have been rarely developed despite their interesting coordination nature and propensity to afford high thermal, moisture and chemical stability. To combine the merits of 1,2,3-triazolate group with the diverse coordination nature of the carboxylate group, we designed a bi-functional organic linker, 4-(1,2,3-triazol-4-yl)benzoate (tab) (Figure 1a) which features both 1,2,3-triazolate and carboxylate binding heads. The self-assembly of the tab ligand with Zn(NO3)_2 under solvothermal conditions affords a porous MOF, termed MTAF-1 (MTAF denotes Metal-TriAzolate Framework) which possesses a double-walled structure and a pentanuclear zinc cluster as secondary building unit (SBU), as well as exhibits permanent porosity with a surface area of 2300 m~2/g and demonstrates interesting selective CO2 uptake performances.