Microporous metal-organic framework zinc(II) imidazole- 4,5-dicarboxylate: Four-fold helical structure and strong fluorescent emission

A novel 3D metal-organic framework of zinc(II) imidazole-4,5-dicarboxylate, [Zn5(L)2(HL)2(DMF)4]n (1) (H3L = 4,5-imidazoledicarboxylic acid), was solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic system with the space group Pbca and cell parameters a = 14.1613(8) Å, b = 15.6764(9) Å, c = 16.1345(9), V = 3581.8(4) Å3 and Z = 4. The crystal structure presents a novel 3D framework with the rare four-fold helical structure and open channels, exhibiting guest-coordination sites at channel walls and strong fluorescent emission.