Solvothermal syntheses and structural characterization of a series of metal–hydroxycarboxylate coordination polymers

The combination of transition metal ions with mixed ligands resulted in the formation of three new coordination polymers, {[Co(C4H4O5)(bpe)(H2O)2] · (0.5bpe)(H2O)}n (1), {[Cu(C4H4O6)(bipy)] · 5H2O}n (2) and {[Cu(C4H4O5)(bpa)] · 2.5H2O}n (3) ( C 4 H 4 O 5 2 - = malate dianion , C 4 H 4 O 6 2 - = tartrate dianion , bpe = 1,2-bis(4-pyridyl)ethene, bipy = 2,2′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane), which were prepared under solvothermal conditions and characterized by single-crystal X-ray diffraction. 1 and 2 feature 1D chain structures. Interestingly, each pair of chains recognizes each other through aromatic π–π stacking interactions, generating a zipper-like double-stranded chain in 2. Compound 3 shows 2D 63 topology framework with a rectangle-like grid.