Synthesis, structures and thermal stabilities of five copper(II) coordination polymers based on 2,4,6-tris(pyridyl)-1,3,5-triazine and 1,2,4,5-benzenetetracarboxylate ligands

Hydrothermal reactions of Cu(II) salts with 2,4,6-tris(3/4-pyridyl)-1,3,5-triazine (3/4-tpt) and 1,2,4,5-benzenetetracarboxylic acid (H4btec) afforded five novel coordination polymers, namely [Cu4(3-tpt)2(btec)2(H2O)4]n·6nH2O (1), [Cu(3-tpt)2(H2btec)]n (2), [Cu3(3-Htpt)2(H2btec)2(btec)]n·4nH2O (3), [Cu2(4-tpt)3(H2btec)2]n·4nH2O (4), and [Cu3(4-tpt)2(Hbtec)2(H2O)]n·3nH2O (5). These complexes exhibit various polymeric networks due to diverse coordination modes of tpt and H4btec. Complex 1 displays a 3-D metal–organic framework in which 3-tpt is an exo-tridentate ligand and μ4-btec4− coordinates to two square-pyramidal Cu(II) and two square Cu(II) ions. Complex 2 is a 1-D chain coordination polymer which contains μ2-H2btec2− bridge and monodentate 3-tpt. Complex 3 shows a 3-D metal–organic framework constructed from protonated bidentate 3-Htpt+, tridentate H2btec2− and tetradentate btec4−. Complex 4 is a 1-D ladder-like coordination polymer assembled by μ2-H2btec2−, mono- and bidentate 4-tpt. Complex 5 exhibits a porous 3-D metal–organic framework constructing from tridentate 4-tpt and μ3-Hbtec3−. Their thermal stabilities were also investigated.