LAUSR

By employing the strategy of positional isomerism, we designed and synthesized two unsymmetrical biphenyl tetracarboxylate ligands, and used them to successfully construct two novel copper-based MOFs. Structural determinations show that the resulting MOFs are three-dimensional networks, each incorporating two different kinds of discrete copper-carboxylate clusters, including the typical dicopper Cu2(COO)4(H2O)2 paddlewheel, as inorganic SBUs, and they display distinctly different topologies, highlighting the significant effect of ligand desymmetrization. ZJNU-9 is a neutral coordination network composed of one typical dicopper paddlewheel and a new dicopper cluster Cu2(COO)4(DMF)2(H2O)2 connected by the organic ligands, while ZJNU-10 is based on one typical dicopper paddlewheel and a new tetracopper cluster Cu4(COO)4(OH)2Cl(H2O)4 linked by the organic ligands to a cationic framework containing three types of cages. The two novel copper-containing clusters discovered in the two compounds greatly enrich the diversity and complexity of inorganic copper-carboxylate SBUs and thus MOF structures. Furthermore, a systematical investigation of their selective adsorption properties with respect to C2H2, CO2, and CH4 through pure-component isotherm measurements and IAST predictions revealed their promising potential for C2H2 recovery and CO2 removal from CH4 under ambient conditions. This work represents a rare example of homometallic pure-carboxylate hetero-SBU MOFs exhibiting highly selective adsorption of C2H2 and CO2 over CH4.