Coordination Polymers Utilizing N-Oxide Functionalized Host Ligands

Pyridyl functionalized host molecules are oxidized to their N-oxide analogues and form a series of coordination polymers and discrete complexes with transition metal cations. Complex {[Ag-3(NMP)(6)(L1)(2)]center dot 3(ClO4)}(infinity) where L1 = tris(isonicotinoyl-N-oxide)cyclotriguaiacylene, NMP = N-methylpyrrolidone, is a three-dimensional (3-D) 3,6-connected coordination polymer of pyrite-like (pyr) topology and features ligand unsupported argentophilic interactions, while two-dimensional (2-D) 3,6-connected coordination polymers with the rarely reported kagome dual (kgd) topology are found for [M(L1)(2)](2+) where M = Zn, Cd, Cu. Ligand L2 = tris(nicotinoyl-N-oxide)cyclotriguaiacylene forms a 2-D coordination polymer with 4(4) (sql) grid topology in complexes {[M(L2)(2)(DMF)(2)]center dot 2ClO(4)center dot 8(DMF)}(infinity) M = Cd or Cu, DMF = N,N'-dimethylformamide, and a double-linked chain structure in {[Co(L2)(2)(DMF)(2)]center dot 2NO(3)center dot 4(DMF)center dot H2O}(infinity) and both types of structure feature hand-shake self-inclusion motifs either within or between the polymers. 2-D coordination networks with 6(3) (hcb) topologies are found in complexes {[M(L3)(NO3)(2)]center dot 2(DMF)}(infinity) (M = Cd, Zn) and {[Cu-5(L3)(2)Cl-10(NMP)(4)]}(infinity) where L3 = tris(2-pyridylmethyl)cyclotriguaiacylene, while [Ag-2(L3)(2)(NMP)(4)]center dot 2(BF4)center dot 2(NMP) has a discrete dimeric structure which again shows hand-shake host guest interactions supported by pi-pi stacking.