Synthesis, crystal structures and properties of two coordination polymers constructed from M2+ (M2+ = Zn2+, Ni2+) with methylenediisophthalic acid and 1,1′-(1,4-butanediyl)bis(imidazole)

Two coordination polymers [Zn2(H2L)2(bbi)(H2O)2·H2O]n 1 and [Ni4(L)2(bbi)2(H2O)4·H2O]n 2 {H4L = methylenediisophthalic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)} have been prepared under hydrothermal conditions and structurally characterized by X-ray diffraction analyses. Mononuclear 1 is a 1D ladder chain and bbi adopts trans-configuration linking two metal centers. Plus the hydrogen binding interactions, it formed a 3D two-fold perpendicular interpenetrating (4, 5)-connected framework. Binuclear units of 2 are connected by L4− and cis-bbi to generate a 3D (4, 6)-connected framework, in which twisted bbi with binuclear units generate the rare triflexure helix. In solid state, complex 1 exhibits yellowgreen emissions at ambient temperature. Magnetic measurements show that there exist weak ferromagnetic interactions in 2.