Self-assembly and structures of new transition metal complexes with phenyl substituted pyrazole carboxylic acid and N-donor co-ligands

Five new transition metal complexes, [Ni(HL1)2(2,2′-bipy)]·3H2O (1), [Ni(HL1)2(4,4′-bipy)] (2), [Co(HL1)2(4,4′-bipy)]·5H2O (3), [Ni2(HL2)4·(4,4′-bipy)·(H2O)2]·4H2O (4), [Co(HL2)2·(4,4′-bipy)] (5) (H2L1 = 5-phenyl-1H-pyrazole-3-carboxylic acid; H2L2 = 3-phenyl-1H-pyrazole-4-carboxylic acid; 2,2′-bipy = 2,2′-bipyridine; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized. Complex 1 exhibits a monomeric structure, 2 and 3 display 1D chain structures, 4 and 5 possess 3D metal-organic frameworks with 1D channels, and all extend to 3D supramolecular networks via rich hydrogen bonds. Complex 4 shows a new (4,6)-connected network with (44·58·63)(54·6·8) topology, while 5 exhibits a NaCl-like network with (412·63) topology. The thermal stabilities of complexes 1–5 and powder XRD of 4 and 5 were investigated. Furthermore, the antibacterial activities of the title complexes against the tested bacteria were studied and compared to the activities of the corresponding free ligands.

Graphical abstractSelf-assembly and structures of five new transition metal complexes with phenyl substituted pyrazole carboxylic acid and N-donor co-ligands.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The five pyrazole carboxylic acid complexes exhibit diverse structures. ► The structures depend on metal ions, N-donor co-ligands, etc. ► Complex 3 crystallize in chiral space group constructing from homohelical chain. ► The complexes exhibit more activity than corresponding free ligands.