PEGylated bis-adamantane carboxamide as guest bridge for graphene poly-cyclodextrin gold nanoassemblies

The incorporation of gold nanoparticles (Au NPs) on graphene (G) is as valuable strategy to produce plas- monic effects that lead to the enhancement of optical absorption, resulting in improved performance of optoelectronic devices. The decoration of G layers by direct reduction of Au 3 + to Au NPs using the chemi- cal functionalities on G surface is preferred since it can result in a huge number of interactions stabilizing Au NPs. The combination of G with polymeric matrices able to act as reducing and capping agents is a successful strategy to achieve this objective. Herein, we demonstrate that both a polymeric cationic cy- clodextrin (PolyCD) and the cyclodextrin units grafted on graphene layers (GCD) can be bridged, in a supramolecular assembly, through the new synthesized pegylated bis-adamantane carboxamide (BisAda) that acts as a “guest bridge”. Moreover, the cyclodextrin functionalities, such as hydroxyl groups, amino groups, hemiacetal groups, act as reductant and stabilizer for the synthesis of Au NPs in an eco-friendly way, alternative to the traditional chemical-reducing methods. Accordingly, the PolyCD@Bis-Ada@GCD as- sembly was decorated in situ with Au NPs by simple addition of PolyCD@BisAda@GCD to a boiling aque- ous solution of Tetrachloro-auric(III) acid.