Characterization and gas adsorption of a novel three-dimensional metal-organic framework (MOF) generated from a new polydentate fluorene-bridged ligand

A polydentate ligand bridged by a fluorene group, namely 9,9-bis(2-hydroxy-ethyl)-2,7-bis(pyridin-4-yl)fluorene (L ), has been prepared under solvothermal conditions in acetonitrile. Crystals of the three-dimensional metal-organic framework (MOF) poly[[[mu(3)-9,9-bis(2-hydroxyethyl)-2,7-bis(pyridin-4-yl)fluorene-kappa(3) N:N':O] bis(methanol-kappa O)(mu-sulfato-kappa(2) O:O') nickel(II)] methanol disolvate], {[Ni(SO4)(C27H24N2O2)(CH3OH)]center dot 2CH(3)OH}(n), (I), were obtained by the solvothermal reaction of L and NiSO4 in methanol. The ligand L forms a two-dimensional network in the crystallographic bc plane via two groups of O-H center dot center dot center dot N hydrogen bonds and neighbouring two-dimensional planes are completely parallel and stack to form a three-dimensional structure. In (I), the Ni II ions are linked by sulfate ions through Ni-O bonds to form inorganic chains and these Ni-containing chains are linked into a three-dimensional framework via Ni-O and Ni-N bonds involving the polydentate ligand L. With one of the hydroxy groups of L coordinating to the Ni-II atom, the torsion angle of the hydroxyethyl group changes from that of the uncoordinated molecule. In addition, the adsorption properties of (I) with carbon dioxide were investigated.