Green Synthesis of Hydroxylatopillar[5]arene-Modified Gold Nanoparticles and Their Self-Assembly, Sensing, and Catalysis Applications

A novel, green, one-pot synthesis of gold nanoparticles (AuNPs) was obtained by the redox reaction between AuCl4– and hydroxylatopillar[5]arene (HP5) in aqueous solution with the aid of OH– at room temperature without the need of a traditional harsh reducing agent such as NaBH4, N2H4, etc. Monodisperse AuNPs with a uniform diameter of ∼5.0 nm are fabricated via the proposed one-step colloidal synthesis route by using HP5 as both reducing agent and stabilizer, while AuNPs cannot be effectively protected by noncyclic monomers of HP5. The FTIR, 13C NMR, and XPS studies demonstrated that the hydroxy groups in HP5 reduce Au3+ into Au0, which leads to nucleation, growth, and formation of AuNPs, and the hydroxy groups themselves are oxidized to carboxyl groups. It is surprising that the HP5 functionalized AuNPs can self-assemble and form multiple well-defined architectures, including vesicles, like nanotubes, and one-/two-dimensional (1D/2D) nanostructures without the need of a guest mediator. The self-assembly ...