Three new metal-organic frameworks based on 2-propyl-1H-imidazole-4,5- dicarboxylate: Synthesis, crystal structure and luminescent properties

Three new complexes [Cd(H2pimda)2(H2O)2]·4H2O (1), [Zn(H2pimda)2(H2O)2].3.5H2O (2) and [Cd2(Hpimda)2(DMF)2]n (3) (H3pimda=2-propyl-1H-imidazole-4,5-dicarboxy acid, DMF=N,N′-dimethylformamide) have been synthesized under hydrothermal or solvothermal conditions, respectively. Crystal structures of complexes 1–3 were determined by single crystal X-ray diffraction. Crystallographic studies on 1 and 2 reveal that both complexes are six-coordinated, whose geometries can be best described as distorted octahedral. Complex 3 was synthesized based on that of complexes 1 and 2. We change the coordination environment of H3pimda during the synthesis process of complex 3 by using organic acid and solvent, accordingly result in different structures ranging from 0D for 1 and 2 to infinite 2D network for 3. Complexes 1–3 have blue luminescence at room temperature in the dimethylsulfoxide (DMSO) solution, which are potential blue luminescence materials. The blue luminescence of complexes 1–3 is due to π∗→π transitions of intra-ligand.