Dicarboxylate anion-dependent assembly of Ni(II) coordination polymers with 4,4′-dipyridyl sulfide

Abstract

Four new coordination polymers, [Ni(isop)(bps)(H2O)]2n·5H2O (1), [Ni(O2N–BDC)(bps)(H2O)]2n (2), [Ni(OH–BDC)(bps)2(H2O)]n (3) and {[Ni2(H2O)(tbip)2(bps)2]}n (4) (bps = 4,4′-dipyridyl sulfide, H2isop= isophthalic acid, O2N–BDC = 5-nitroisophthalic acid, OH–BDC = 5-hydroxyisophthalic acid, H2tbip = 5-tert-butyl isophthalic acid), have been isolated from parallel hydrothermal reactions of Ni(OAc)2·4H2O and bps with isop, O2N–BDC, OH–BDC and H2tbip, respectively. Compound 1 is an unusual 2D double layered supramolecular motif generated by hydrogen bonding interactions of two single 2D (4,4) networks. Compound 2 has a highly puckered 2D (4,4) sheet and further stack viaO⋯O intermolecular contacts to form a 3D supramolecular structure. Compound 3 features a 2D rectangular grid layer with terminal bps ligands projecting into the interlayer space, leading to a highly interdigitated packing motif and further expansion to generate a 3-D network through interlayer C–H⋯π stacking interactions. Compound 4 contains [Ni2(H2O)]4+ dimers bridged by pairs of ligands into a single 3D diamond network with alternately left-handed and right-handed helical channels. As compared to isop, the coexistence of electron-donating (–OH, –C(CH3)3) or electron-withdrawing (–NO2) groups in the dicarboxylate derivatives has a significant effect on the molecular self-assembly. Variable-temperature magnetic susceptibility measurements reveals the existence of weak ferromagnetic interactions between the nickel centers in 4.