Preparation of Tris-Tetrazole-Based Metallogels and Stabilization of Silver Nanoparticles: Studies on Reduction Catalysis and Self-Healing Property

An ionic multifunctional gelator molecule triethylammonium 5-(3,5-bis((1H-tetrazol-5-yl)carbamoyl)benzamido)tetrazol-1-ide G7 is synthesized and characterized by spectroscopic tools and mass spectrometry. G7 tends to form a stable organogel in a mixture of N,N-dimethylformamide/dimethylsulfoxide (DMF/DMSO) and water. Introduction of different metal perchlorate salts in a DMSO solution of G7 furnished a series of metallogels M1G7, M2G7, M3G7, M4G7, M5G7, M6G7, and M7G7 [M1 = Fe(III), M2 = Co(II), M3 = Cu(II), M4 = Zn(II), M5 = Ag(I), M6 = Ni, and M7 = Fe(II)]. Among them, M1G7, M3G7, M4G7, M6G7, and M7G7 help individually in the synthesis and stabilization of bimetallic nanocomposites containing silver nanoparticles (AgNPs). Iron(III)-containing nanocomposites M1G7AgNPs have been utilized in the form of catalysts in the reduction reaction of nitroaromatic compounds to corresponding amines with a quantitative yield. The organogel G7 has also shown the abilities to absorb different metal ions from aqueous solutions and allow selective transition of M1G7 from the gel state to the crystalline state. Fe(III) formed dual metallogels with Zn(II), which can be used for further applications. Furthermore, the nanocomposite M1G7AgNP powder, in the presence of the organogel G7, gets converted into a nanostructured metallogel, which shows exclusive self-healing properties. This is the first example where a nanocomposite powder contains the dual-metal system (Fe(III) and Ag(0)) and shows a reduction catalytic property, and its nanostructured dual-metallogel form manifests the self-healing property in a fabricated metallogel.