Synthesis, crystal structure and luminescence of zinc(II) coordination polymers based on a flexible bifunctional terpyridyl carboxylic ligand

The new ligand 4′-(4-carboxy-methyleneoxyphenyl)-2,2′:6′,2″-terpyridine (HL) and its five zinc coordination polymers, [Zn(L)Cl]2n·nH2O (1), [Zn(L)(bdc)0.5]n·2nH2O (2), [Zn(L)(adip)0.5]n·3nH2O (3), [Zn(L)(suc)0.5]n (4) and [Zn(L)(fum)0.5]n (5), were synthesised and characterised. Single crystal X-ray diffraction analyses revealed that compounds 1–3 are one-dimensional (1D) chains. Compounds 4 and 5 have similar structures which demonstrate triple-stranded helical chains and a 3-fold 2D interpenetrated network. The plentiful hydrogen-bonding sites and π–π interactions originating from the pyridyl rings of the ligand HL greatly contribute to the structures in complexes 1–5, exhibiting an intriguing ability in supramolecular assembly. In addition, the thermal stabilities and photoluminescence properties of complexes 1–5 were also studied in the solid state.

Graphical abstractA new flexible carboxylic derivative of the 2,2′:6′,2″-terpyridine ligand and a series of dicarboxylate ligands with ZnII cations produce five diverse coordination polymers under hydrothermal or solvothermal conditions. The five complexes were crystallised in three structural types by changing the length of the dicarboxylate ligands. This investigation demonstrates that networks may be modified by bridging carboxylate ligands.Figure optionsDownload full-size imageDownload as PowerPoint slide