Syntheses and characterizations of three coordination polymers based on dipyridylbenzoates and 1,4-bezenedicarboxylate

Three coordination polymers, namely [Ni(3,4-pmb)(bdc)0.5] (1), [Co(3,5-pmb)(bdc)0.5] (2) and [Cd(3,5-pmb)(bdc)0.5] (3) (3,4-pmb = 3,4-bis[4-pyridylmethyleneoxyl]benzoate, 3,5-pmb = 3,5-bis[4-pyridylmethyleneoxyl]benzoate and bdc = 1,4-benzenedicarboxylate), have been synthesized by the hydrothermal method and structurally characterized. The X-ray structural analysis reveals that the three complexes possess different structural motifs. Complex 1 has a three-dimensional (3D) threefold interpenetrated diamondiod architecture and crystallizes in the monoclinic C2/c space group, in which each Ni(II) atom is connected to four other Ni(II) centers, resulting in the formation of a (4,4) diamondoid network. Complex 2 is a (3D) fourfold interpenetrated polyrotaxane and crystallizes in the monoclinic P2(1)/c space group. It is constructed by four equivalent independent 3D units and entangled by each other give a 3D fourfold structure. Complex 3 is a 2D network in which two Cd(II) centers are bridged equivalently by four carboxylate groups of different pmb and bdc ligands, forming a paddle wheel secondary building unit (SBU) (CdO4N), and the five coordinating atoms in the CdO4N unit occupy the vertices of square-pyramidal structure. Moreover, complex 3 exhibits strong photoluminescence at room temperature.

Graphical abstractThe coordination polymers, [Ni(3,5-pmb)(bdc)0.5] (1), [Co(3,5-pmb)(bdc)0.5] (2) and [Cd(3,5-pmb)(bdc)0.5] (3), have been synthesized by the hydrothermal method. X-ray analysis reveals that complex 1 has a three-dimensional (3D) threefold interpenetrated diamodiod architecture, complex 2 is a 3D fourfold interpenetrated polyrotaxane, while complex 3 is a 2D network with paddle wheel dimeric cadmium–tetracarboxylate building units.Figure optionsDownload full-size imageDownload as PowerPoint slide