| Metal-organic coordination polymers have attracted considerable attentionbecause of their fascinating structural diversities and their potential application inmagnetic, luminescent, adsorption etc. Among them, the construction of helicalcoordination polymers has aroused much more attention owing to the wideappearance of helical structures in proteins, collagens, quartz, single-walled carbonnanotubes, and many more natural or artificial fiber-type derivatives. Helicalcoordination polymer has become one of the research hotspots in coordinationchemistry and material science because of their special structural characteristics andunique functional features as well as potential applications in many fields (optic,asymmetric catalysis, biomimetic materials, sensors, etc). However, it is filled withchallenges to select and design appropriate ligand to direct self-assembly helicalcoordination complexes with specific function, and it is unlimited potential toresearch in helical coordination complexes.In this paper, a new V-shaped ligand of2,2′-[hexafluoroisopropylidenebis(p-phenyleneoxy)]diacetic acid (H2L) was synthesised and as main ligand, and differentN-donor ligands2,2′-bipyridine (2,2′-bipy),1,10-phenanthroline (phen),4,4′-bipyridine (4,4′-bipy) are as auxiliary ligands，and react with transition metal salt,rare earth metal salt respectively. Meanwhile seventy new transition metal complexesand five rare earth metal complexes were prepared via hydrothermal techiques andstructurally characterized by elemental analyses, infrared spectra, powder X-raydiffraction (PXRD) and single crystal X-ray diffraction. In addition, thermal stability,magnetic and fluorescence properties of free ligands and their complexes were studied.Complexes [Mn(L)(4,4′-bipy)]·H2O (1),[Cu(L)(4,4′-bipy)]·H2O (8) and[Cd(L)(4,4′-bipy)]·H2O (14) are isostructural as well as [Co(L)(4,4′-bipy)(H2O)](4)and [Ni(L)(4,4′-bipy)(H2O)](5), and they all display2D layer structures containingsingle-stranded helical chain with the connection of H2L ligand.[Co(L)(2,2′-bipy)(H2O)](2),[Cu(L)(2,2′-bipy)(H2O)](6) and [Zn(L)(2,2′-bipy)(H2O)](10) areisostructural, and exhibit1D chain structure, while [Co(L)(phen)(H2O)]·H2O (3) and[Cu(L)(phen)(H2O)]·H2O (7) are isostructural, and display monomeric structure. It isworthy noting that complexes2,3,6,7,10all form helical chain with the help ofhydrogen bonding interaction. Complex [Zn2(L)(OH)(O)0.5]·0.5H2O (9) displays a3D metal-organic framework and consists of single-stranded helical chains. Complexes[Zn3(L)3(phen)2]·H2O (11),[Cd(L)(phen)](13),[Pb(L)(phen)](16) all display2Dlayer structures, and further extend into3D supramolecular networks containingsingle-stranded hydrogen-bonded helical chains via hydrogen bonding interactions.Complexes [Zn2(L)2(4,4′-bipy)](12) and [Pb(L)(H2O)](15) show2D layer structuresand comprise of single-stranded helical chains. Complex [Pb2(L)2(4,4′-bipy)0.5](17)has an interesting structure, which displays a3D metal-organic framework containingtwo kinds of differnt double-stranded helical chains and one kind of single-strandedhelical chain, and two kinds of double-stranded helical chains interlinked each other.Complexes [Y(L)1.5](18),[La(L)1.5(H2O)]·H2O (19),[Ce(L)1.5](20),[Pr(L)1.5](21)and [Eu(L)1.5](22) posses3D metal-organic frameworks, of which18,20,21and22are isostructural. Complexes18and20-22contain double-stranded right-handedhelical chain, so they are chirality compounds and consist with the space group ofthem. Complex19comprises two kinds of differnt single-stranded helical chains.Furthrmore, thermal stability， magnetic and fluorescence properties of freeligands and their complexes were studied. All other complexes showed excellentthermal stability except that complex [Zn2(L)(OH)(O)0.5]·0.5H2O (9) has low heatstability. H2L and complexes9-17and22showed good fluorescence properties.Complexes1,3,4,7and8are ferromagnet. So it is foreseeable that these complexeshave potential applications in fluorescent materials and magnetic materials. |
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