Synthesis of gold nanoparticles and nanoclusters in a supramolecular gel and their applications in catalytic reduction of p-nitrophenol to p-aminophenol and Hg(II) sensing

A new series of urea/amide functionalized bis-pyridyl compounds was found to give gels in various solvent systems, viz. DMF-water, DMSO-water, ethylene glycol-water and nitrobenzene. On sprinkling solid HAuCl4 center dot xH(2)O, in these gels, small gold nano-clusters/gold nano-particles (AuNCs/AuNPs) were found to form, without the use of any exogenous reducing agent. The AuNPs embedded gels were capable of catalyzing the reduction of p-nitrophenol to p-aminophenol and that too without any external reducing agent like NaBH4. The small gold nanoclusters formed in the nitrobenzene gel of the gelators were fluorescent and this property has been exploited for sensing of Hg(II).