Flexible Zn-MOF Exhibiting Selective CO₂ Adsorption and Efficient Lewis Acidic Catalytic Activity

Abstract

A two-dimensional, tetragonal porous metal organic framework {[Zn2(TBIB)2(HTCPB)2]·9DMF·19H2O}n (1) has been synthesized under hydrothermal conditions by employing 1,3,5-tri(1H-benzo[d]imidazol-1-yl)benzene (TBIB) and 1,3,5-tris(4′-carboxyphenyl-)benzene (H3TCPB). But noncovalent supramolecular interactions between the layers make this framework three-dimensional, generating porosity in one dimension. Flexibility arises due to the presence of two types of large linkers wherein some functional groups of the ligands are not coordinated with the metal ion. Desolvated polymer shows moderate CO2 uptake (65 cm3 g–1 at 195 K and 1 bar) at low temperature and pressure. Compound 1 acts as a highly efficient heterogeneous catalyst toward the formation of cyclic carbonate through cycloaddition of CO2 as well as toward the synthesis of quinoline derivatives by the Friedländer reaction. The presence of the free −COOH, −C═O groups and uncoordinated −N atoms on the wall of the pores makes this framework an excellent candidate for the catalytic reactions without activation of the compound.