Syntheses, structures and fluorescence properties of cadmium coordination polymers with triangular 1,3-bis[2-(4′-pyridyl)ethenyl]benzene and linear dicarboxylic acids

• Three new polymeric complexes based on triangular 1,3-BPEP were synthesized.
• Diversity structures were obtained due to the different molecular lengths of carboxylic acid.
• Thermal and fluorescence properties of these complexes were investigated.

Three new polymeric complexes [Cd3(1,3-BPEB)3(1,4-BDC)3·2H2O]n (1), [Cd2(1,3-BPEB)2(4,4′-BPDC)2]n (2) and [Cd2(1,3-BPEB)2(4,4′-STDC)2]n (3) (1,3-BPEB = 1,3-bis[2-(4′-pyridyl)ethenyl]benzene, 1,4-BDC = 1,4-benzenedicarboxylic acid, 4,4′-BPDC = 4,4′-biphenyldicarboxylic acid and 4,4′-STDC = 4,4′-stilbenedicarboxylic acid) have been prepared by the solvothermal reaction of 1,3-BPEB, Cd(NO3)2·4H2O and dicarboxylic acids. Single-crystal X-ray diffraction reveals that these complexes have novel complicated structures. Complex 1 is a 3-D network structure by linking Cd atoms with 1,4-BDC and 1,3-BPEB ligands. Complex 2 shows a 3-D interpenetrating layered structure formed by three networks which derived from bridged Cd atoms with 4,4′-BPDC and 1,3-BPEB ligands. Complex 3 has a fivefold interpenetrating 3-D coordination framework by linking Cd atoms with 4,4′-STDC and 1,3-BPEB ligands. The dicarboxylic acids afford different coordination modes to bind Cd atoms in these three complexes. Additionally, these compounds were further characterized by PXRD, FT-IR spectroscopy and thermogravimetric (TG) analysis. Their fluorescence spectra were also determined and analyzed in the solid state at room temperature.

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