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 {[Ag3(NMP)6(L1)2]·3(ClO4)}∞ 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 44 (sql) grid topology in complexes {[M(L2)2(DMF)2]·2ClO4·8(DMF)}∞ M = Cd or Cu, DMF = N,N′-dimethylformamide, and a double-linked chain structure in {[Co(L2)2(DMF)2]·2NO3·4(DMF)·H2O}∞, and both types of structure feature hand-shake self-inclusion motifs either within or between the polymers. 2-D coordination networks with 63 (hcb) topologies are found in complexes {[M(L3)(NO3)2]·2(DMF)}∞ (M = Cd, Zn) and {[Cu5(L3)2Cl10(NMP)4]}∞ where L3 = tris(2-pyridylmethyl)cyclotriguaiacylene, while [Ag2(L3)2(NMP)4]·2(BF4)·2(NMP) has a discrete dimeric structure which again shows hand-shake host–guest interactions supported by π–π stacking.