American Chemical Society
cg401149h_si_002.cif (100.24 kB)

Crystal Structures and Spectroscopic Properties of Metal–Organic Frameworks Based on Rigid Ligands with Flexible Functional Groups

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posted on 2014-02-05, 00:00 authored by Chuanlei Zhang, Mingdao Zhang, Ling Qin, Hegen Zheng
Two rigid linear ligands with alkoxy functional groups (L1 = 4,4′-(2,5-dimethoxy-1,4-phenylene) dipyridine; L2 = 4,4′-(2,5-diethoxy-1,4-phenylene) dipyridine) incorporating carboxyl-containing auxiliary ligands (isophthalic acid = H2IPA; terephthalic acid = H2TPA; biphenyl-4,4′-dicarboxylate = H2BPDC) have been adopted to build a series of complexes with M­(II) (M = Zn, Co, Cd) under solvothermal conditions. The formula of these complexes are {[Zn­(L1)­(IPA)]}n (1), {[Zn­(L1)­(TPA)]·DMF}n (2), {[Co­(L1)­(TPA)­(H2O)2]·2DMF}n (3), {[Cd­(L1)­(TPA)­(H2O)2]·2DMF}n (4), and {[Co­(L2)­(BPDC)]·0.5H2O}n (5). Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. Topological analyses reveal that complex 2 is a 6-connected pcu net with point symbol {412·63}, while complex 5 is a 6-connected rob net with point symbol {48·68·8}, the other complexes 1, 3, and 4 can be simplified as 4-connected sql nets with point symbol {44.62}. Complexes 1, 3, and 4 are 2D layer motifs, 2 and 5 are both 2-fold interpenetrating 3D frameworks. The optical absorption spectra of 3 and 5 indicate the nature of semiconductivity. The strong fluorescence emissions and long emission lifetimes of 1, 2, and 4 display that they are promising phosphorescent materials.