Metallogels in catalysis

Abstract

A gelator molecule N2 , N4 , N6 -tri(pyridin-2-yl)-1,3,5-triazine-2,4,6- triamine (PN2) has been synthesized and characterized well by ESI-MS and 1H NMR spectroscopy techniques. PN2 shows stable gel formation in the presence of triethylammonium 5-(3,5-bis((1H-tetrazol-5- yl)carbamoyl)benzamido)tetrazol-1-ide (G7) which acts as a trigger molecule for the gel formation of PN2. The combination of G7 and PN2 tends to show stable organogelation and metallogelation in the DMSO-H2O solvent mixture. The thermal study of PN2, G7 and xerogels of G7PN2 has been done by TGA analysis. Three metallogels namely M1G7PN2, M2G7PN2, and M3G7PN2 [M1=Fe (III), M2=Cu (II), and M3=Ag(I)] were obtained from the combined gelator system. The morphology transformation from organogels to metallogels have been investigated by FE-SEM analysis. Among these, the synthesis and stabilization of silver nanoparticles has been done using M1G7PN2. These M1G7PN2AgNPs nanocomposite have been used as catalysts to reduce nitro-substituent into their amine product. UV-vis spectroscopy was used to check the progress of the reaction. 1H NMR was also used to confirm the reduction process. In addition, the nanocomposite M1G7PN2AgNP powder is also transformed into a metallogel in the presence of the G7 and PN2. This metallogel also shows thixotropic behavior which was confirmed by time oscillation sweep experiments.