Europium-cadmium organic framework with zwitterionic ligand exhibiting tunable luminescence, CO2 adsorption and dye degradation

Porous lanthanide-transition heterometallic metal-organic frameworks (MOFs) as a subclass of porous hybrid materials have attracted considerable attention as a new advance in the research on MOFs. However, rationally designing and constructing heterometallic MOFs with desirable properties remains a challenging task. In this work, involving the heterometallic cooperative crystallization method, a novel europium-cadmium MOF based on a zwitterionic carboxylate ligand, [EuCd(pbbp)2(SO4)2Cl2(H2O)3] (1), (H2pbbp·2Cl ​= ​1,1'-(1,4-phenylene-bis(methylene))-bis(3-carboxy pyridinium) dichloride), has been solvothermally synthesized. Complex 1 was characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The structure of complex 1 consists of Eu–Cd heterometallic chains with one-dimensional channels. Complex 1 shows interesting excitation-dependent luminescence at room temperature. The gas adsorption studies show that complex 1 exhibits highly selective adsorption of CO2 over N2 and H2 under ambient conditions, which may be caused by the stronger interaction of CO2 with the positively charged pyridinium functional groups. In addition, the photocatalytic activity studies indicate that complex 1 shows good activity in rhodamine B dye degradation.