Metallogels Derived from Silver Coordination Polymers of C3-Symmetric Tris(pyridylamide) Tripodal Ligands: Synthesis of Ag Nanoparticles and Catalysis

By applying a recently developed crystal engineering rationale, four C-3 symmetric tris(pyridylamide) ligands namely 1,3,5-tris(nicotinamidomethyl)-2,4,6-triethylbenzene, 1,3,5-tris(isonicotinamidomethyl)-2,4,6-triethylbenzene, 1,3,5-tris( nicotinamidomethyl)-2,4,6-trimethylbenzene, and 1,3,5-tris( isonicotinamidomethyl)-2,4,6-trimethylbenzene, which contain potential hydrogen-bonding sites, were designed and synthesized for generating Ag-I coordination polymers and coordination-polymer-based gels. The coordination polymers thus obtained were characterized by single-crystal X-ray diffraction. The silver metallogels were characterized by transmission electron microscopy (TEM) and dynamic rheology. Upon exposure to visible light, these silver metallogels produced silver nanoparticles (AgNPs), which were characterized by TEM, powder X-ray diffraction, energy dispersive X-ray and X-ray photoelectron spectroscopy. These NPs were found to be effectively catalyzed the reduction of 4-nitrophenolate to 4-aminophenolate without the use of any exogenous reducing agent.