Facile synthesis of “green” gold nanocrystals using cynarin in an aqueous solution

• Published in: Applied surface science 2014-11, Vol.318, p.191-198
• Main Authors: Katircioğlu, Zeynep, Şakalak, Hüseyin, Ulaşan, Mehmet, Gören, Ahmet Ceyhan, Yavuz, Mustafa Selman
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Artichoke; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Cynarin; Exact sciences and technology; Gold; Nanocrystals; Nanoparticles; Noble metals; Onopordum illyricum L. plant; Palladium; Physics; Silver; Solvents; Stabilizers (agents); Synthesis
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.03.013

•The first time a remarkably simple, versatile, environmentally friendly, one-pot and biogenic fabrication and aqueous synthesis of monodisperse gold nanoparticles by using cynarin.•Cynarin as a reductant and capping agent.•Exclusion of extra reducing agents or reductant.•Fabrication of Pd and Ag nanoparticles using cynarin in aqueous media. Herein we describe a water-based protocol that generates Au nanoparticles (AuNPs) by mixing aqueous solutions of HAuCl4 and cynarin (a natural product extract from artichoke leaf). Based on the observations from 1H NMR spectrum of AuNPs, a polyol oxidation mechanism by metal ions which eventually results in AuNPs formation, is proposed. Basically, the aromatic alcohol groups (1,2-benzenediol) of cynarin are oxidized to α-hydroxy ketone intermediate product, and then further oxidized to the vicinal diketone final product while the Au3+ ions are reduced to its atomic form (Au0) which leads the generation of Au nanoparticles. This new protocol has also been employed to prepare multiply twinned Pd nanoparticles and Ag cubical aggregates. Due to exclusion of organic solvent, surfactant, or stabilizer for all these synthesis, this protocol may provide a simple, versatile, and environmentally benign route to fabricate noble-metal nanoparticles having various compositions and morphologies.