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

Abstract

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.