Two Co(II)-Based MOFs Constructed from Resorcin[4]Arene Ligand: Syntheses, Structures, and Heterogeneous Catalyst for Conversion of CO2

Two Co(II)-based metal–organic frameworks (MOFs) with open channels, [(CH3)2NH2]2[Co5L(H2O)8]·4H2O (1) and [Co6L(DMF)2(H2O)8]·2H2O (2), were synthesized using resorcin[4]arene ligand (H12L). Compounds 1 and 2 exhibit different 3D microporous framework structures: 1 possesses two kinds of open channels parallel to the a-axis (ca. 5.0 × 5.0 A) and the b-axis (ca. 4.0 × 6.0 A), and 2 is an open framework with a window size of 5.6 × 5.6 A. The activated crystal 1 involves many Lewis acid sites; thus, 1 shows prominent activity and recyclability for the reaction of carbon dioxide coupled with epoxides. Most strikingly, catalyst 1 can be reused for five successive cycles and provides outstanding catalytic activity.