Nickel(II) Coordination Polymers Supported by Bis-pyridyl-bis-amide and Angular Dicarboxylate Ligands: Role of Ligand Flexibility in Iodine Adsorption.

Reactions of -bis(3-pyridylmethyl)oxalamide (), -bis(4-pyridylmethyl)oxalamide (), or -bis(3-pyridylmethyl)adipoamide) () with angular dicarboxylic acids and Ni(II) salts under hydro(solvo)thermal conditions afforded a series of coordination polymers: {[Ni()(OBA)(HO)]·HO} (HOBA = 4,4-oxydibenzoic acid), , {[Ni()(SDA)(HO)]·HO·CHOH} (HSDA = 4,4-sulfonyldibenzoic acid), , {[Ni()(OBA)]·CHOH}, , {[Ni()(OBA)]·CHOH}, , {[Ni()(SDA)(HO)]·5HO}, , {[Ni()(SDA)(HO)]·HO·2CHOH}, , {[Ni()(OBA)(HO)]·2HO}, , {[Ni()(SDA)(HO)]·2HO}, , and {[Ni().(SDA)(HO)]·0.5CHOH}, , which have been structurally characterized by using single-crystal X-ray crystallography. Complex exhibits an interdigitated 2D layer with the 2,4L2 topology and is a 2D layer with the topology, while and are 3D frameworks resulting from polycatenated 2D nets with the topology and and are 2-fold interpenetrated 3D frameworks with the topology. Complexes and are 1D looped chains and is a 2D layer with the 3,4L13 topology. The various structural types in - indicate that the structural diversity is subject to the flexibility and donor atom position of the neutral spacer ligands and the identity of the angular dicarboxylate ligands, while the role of the solvent is uncertain. The iodine adsorption of - was also investigated, demonstrating that that the flexibility of the spacer - ligands can be an important factor that governs the feasibility of the iodine adsorption. Moreover, complex shows a better iodine adsorption and encapsulates 166.55 mg g iodine in the vapor phase at 60 °C, which corresponded to 0.38 molecules of iodine per formula unit.