Four d10 metal coordination polymers based on 2-(4-carboxyphenyl)-1H-imidazole-4,5-dicarboxylic acid and auxiliary N-containing ligands: Syntheses, structures, photoluminescence and sensing properties

Abstract Four new CPs, [Zn5(HCpIDC)2(trz)4(H2O)2]n (1), {[Cd2(HCpIDC)(ttz)(H2O)2]∙H2O]}n (2), {[Zn(H2CpIDC)(tib)]∙4H2O]}n (3) and {[Zn3(HCpIDC)2(tib)(H2O)2]∙H2O]}n (4) [H4CpIDC = 2-(4-carboxyphenyl)-1H-imidazole-4,5-dicarboxylic acid, Htrz = 1,2,4-triazole, Httz = 1H-tetrazole and tib = 1,3,5-tri(1H-imidazol-1-yl)benzene)], have been hydrothermally synthesized by fine control over the synthetic conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses and thermogravimetric analyses (TGA). The H4CpIDC ligands can be deprotonated into H2CpIDC2–, HCpIDC3– or CpIDC4– anions and they can coordinate to the metal centers in monodentate, μ3, μ4 or μ5 modes in the four complexes. Complex 1 possesses a 3D framework with a new (3,4,5)-connected topology constructed from interconnected trz-Zn-CpIDC layers. Complex 2 is a 3D (4,6)-connected network formed by [Cd(ttz)]n helixes linking [Cd2(HCpIDC)]n layers. Complex 3 displays an interdigitated 3D architecture based on a simple 2D fes network. Complex 4 exhibits a complicated 3D (3,4)-connected framework built by interconnected sloping ladder-like pillar SBUs. Complexes 1–4 exhibit strong ligand-based blue fluorescence, showing their potential for being solid-state luminescent materials. Meanwhile, complex 1 is further proven to be a promising sensor towards Fe3+ ions in aqueous solution, with high sensitivity and selectivity.