Systematic design and research on a series of cadmium coordination polymers assembled due to tetracarboxylate ligands

•Tetracarboxylate ligands based on terphenyl moiety have been used.•Several factors that influenced the architecture have been discussed.•Luminescent properties have been investigated.

A series of metal-organic frameworks (MOFs) have been prepared by tetracarboxylate ligands and Cd(II) ions under the hydrothermal or solvothermal conditions with the formulas of {[Cd2(L1)(H2O)4]·H2O}n (1), {[(CH3)2NH2]2[Cd(L1)]}n (2), [Cd(L2)0.5(H2O)]n (3), {[(CH3)2NH2]2 [Cd(L2)]·2DMF}n (4), [Cd(L3)0.5(H2O)]n (5), {[Cd(L3)0.5(H2O)]·CH3OH}n (6), {[(CH3)2NH2]2[Cd3(L4)2]}n (7) (H4L1=[1,1′:4′,1″-terphenyl]-2,2″,5,5″-tetracarboxylic acid; H4L2=[1,1′:4′,1″-terphenyl]-2′,4,4″,5′-tetracarboxylic acid; H4L3=[1,1′:3′,1″-terphenyl]-2′,3,3″,5′-tetracarboxylic acid; H4L4=[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid), which are characterized by single-crystal X-ray diffraction, elemental analyses, IR, TGA and PXRD. Complex 1 exhibits a three-dimensional (3D) supramolecular framework based on two-dimensional (2D) coordination networks. Complexes 2 and 4 possess 3D framework based on the 1D right-handed helix channels. Complexes 3 and 7 are a 3D architecture containing two different channels. Isostructural complexes 5 and 6 display 3D framework. The different synthetic methods and coordination modes of the tetracarboxylates ligands have effect on formation of various MOFs. Moreover, the luminescent properties and N2 adsorption behaviors have been reported.

Graphical abstractA series of cadmium(II) high-dimensional coordination polymers constructed from four different kinds of tetracarboxylate ligands have been successfully prepared under hydrothermal or solvothermal conditions. The effect of solvents, the coordination modes of the tetracarboxylates and positions of carboxylate groups on the architectures of complexes 1–7 have been investigated in detail. The luminescent properties of the part of complexes, N2 adsorption behaviors of complexes 2, 4–7 have also been studied.Figure optionsDownload full-size imageDownload as PowerPoint slide