A stable Co(Ⅱ)-based metal-organic framework with dual-functional pyrazolate-carboxylate ligand:Construction and CO2 selective adsorption and fixation

By taking the functional adva ntages of both pyrazolate and carboxylate ligands,a unique dual-functional pyrazolate-carboxylate ligand acid,4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid(HPCBA) was designed and synthesized.Using it,a new Co(Ⅱ)-based metal-organic framework(MOF),Co(PCBA)2(HO)2(BUT-75) has been constructed.It revealed a(3,6)-connected net based on the 6-connected linear trinuclear metal node,and showed good chemical stability in a wide pH range from 3 to 12 at room temperature,as well as in boiling water.Due to the presence of rich exposed Co(Ⅱ) sites in pores,BUT-75 presented high selective COadsorption capacity over Nat 298 K.Simultaneously,it demonstrated fine catalytic performance for the cycloaddition of COwith epoxides into cyclic carbonates under ambient conditions.This work has not only enriched the MOF community through integrating diverse functio nalities into one ligand but also contributed a versatile platform for COfixation,thereby pushing MOF chemistry forward by stability enhancement and application expansion.