Coordination assemblies of Zn(NO3)2 with 4-pyr-poly-2-ene and polycarboxylates: structural diversification and photoluminescence properties

Abstract

Five zinc coordination polymers, {[Zn₂(1,4-BDC)₂(ppene)]·2H₂O}_n (1), {[Zn(CCN)(ppene)]·H₂O}_n (2), {[Zn(5-Me-1,3-BDC)(ppene)]·2H₂O}_n (3), {[Zn₂(5-NH₂-1,3-BDC)₂(ppene)]·3H₂O}_n (4) and [Zn₂(BTA)(H₂BTA)(Hppene)₂]_n (5) with different structures have been prepared based on the hydrothermal reactions between Zn(NO₃)₂·6H₂O and the dipyridyl linker 4-pyr-poly-2-ene (ppene) in the presence of 1,4-benzenedicarboxylic acid (1,4-H₂BDC), 4-carboxycinnamic acid (H₂CCN), 5-methyl-1,3-benzenedicarboxylic acid (5-Me-1,3-H₂BDC), 5-amino-1,3-benzenedicarboxylic acid (5-NH₂-1,3-H₂BDC) and 1,2,4,5-benzenetetracarboxylic acid (H₄BTA), respectively. Complexes 1–5 have been structurally characterized by IR spectroscopy, elemental analysis, single crystal X-ray diffraction analysis and powder X-ray diffraction analysis. Compound 1 exhibits a 3D three-fold interpenetrating pcu network with the Schläfli symbol 4¹²6³. 2 shows a six-fold interpenetrating framework with 6⁶ diamondoid topology. 3 presents a staircase-like 2D (4,4) net. 4 displays a 2D (3,4)-connected framework with the Schläfli symbol (6³)(6⁵8). 5 comprises a complicated 3D (3,4,6)-connected supramolecular framework based on the interconnection of 2D coordination polymers through hydrogen bonding interactions. The supramolecular framework of compound 5 denotes a point symbol of (4·8²)₂(6⁴8²)(4²6⁶8⁵10²). Thermal stability and photoluminescence properties of these five coordination polymers in the solid state have also been investigated.