Metallogels and silver nanoparticles generated from a series of transition metal-based coordination polymers derived from a new bis-pyridyl-bis-amide ligand and various carboxylates

Abstract

A new series of coordination polymers, namely, CP2 [{(H₂O)Co_1.5 (μ-3-bpna) _1.5(μ-btc)}·3DMF·3H₂O]_α, CP3 [{Cd(μ-3-bpna)(μ-hbtc)}·CH₃OH·2H₂O]_α, CP4 [{Co(μ-3-bpna)(μ-ipa)}·DMF·2H₂O]_α, CP5 [{Co(μ-3-bpna)(μ-1,3-pda)}·DMF]_α, CP6 [Cd(μ-3-bpna)0.5(μ-1,3-pda)]_α, CP7 [(H₂O)Co_0.5(μ-3-bpna)_0.5(μ-1,4-pda)_0.5]_α, and CP8 [{Zn(μ-3-bpna)(μ-oba)}·DMF·2H₂O]_α, has been synthesized by reacting a hydrogen-bond-functionalized bis-pyridyl ligand, namely, N′,N″-di(pyridin-3-yl)naphthalene-2,6-dicarboxamide, with various transition metal salts and different di- or tricarboxylates (as co-ligand) displaying 2D and 3D network topology and having lattice-occluded solvents in the majority of cases. A 1D coordination polymer, namely, CP1 [{Ag_0.5(μ-3-bpna)}_0.5·0.5BF₄CH₃CN]_α, has also been isolated by reacting 3-bpna with AgBF₄ in the absence of any carboxylate co-ligand. All of the CPs were characterized by single crystal X-ray diffraction. Interestingly, two such CPs, namely, CP1 and CP2, produced metallogels, which were characterized by rheology, transmission electron microscopy, and X-ray powder diffraction. The metallogel of CP1 produced Ag nanoparticles within the gel bed upon exposure to light.