A series of coordination polymers constructed by 2-phenylsuccinic acid and flexible bis(imidazole) ligands: Syntheses, structures, and photoluminescent properties

Abstract

Eight coordination polymers (CPs), namely, [Co(μ-phsuc)(μ-obix)]n(1), {[Co2(μ-phsuc)2(μ-pbix)1.5]⋅2H2O}n(2), [Zn(μ-phsuc)(μ-obix)]n(3), {[Zn(μ-phsuc)(μ-mbix)]⋅H2O}n(4), {[Zn(μ-phsuc)(μ-pbix)]⋅H2O}n(5), {[Zn(μ-phsuc)(μ-pbix)]⋅1.5H2O⋅CH3OH}n(6), [Cd(μ-phsuc)(μ-obix)]n(7) and [Cd(μ3-phsuc)(μ-pbix)0.5]n(8) (phsucH2 = 2-phenylsuccinic acid, obix = 1,2-bis((imidazol-1-yl)methyl)benzene, mbix = 1,3-bis((imidazol-1-yl)methyl)benzene, pbix = 1,4-bis((imidazol-1-yl)methyl)benzene), were solvothermally synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermal analyses. The structural analyses revealed that the compounds were 2D coordination polymers, in which metal ions were in tetrahedral coordination geometries in 1-6 and in octahedral coordination geometries in 2, 7 and 8. Compounds 1, 3, 4, 5, 7 and 8 displayed 4-connected 2D wave sheets with the point symbol of {44.62}. Compound 2 was rare example exhibiting a 2D polyrotaxane structure. Compound 6 showed a two-fold interpenetrated 2D structure with hcb topology (the point symbol of {63}). In the compounds, the neighboring 2D layers were further assembled by π⋅⋅⋅π stacking and weak C–H⋅⋅⋅π interactions into the 3D supramolecular framework. The effects of the bis(imidazole) linkers and metals ions on the framework assemblies have been discussed. In addition, thermal and photoluminescent and optical properties of the compounds were investigated.