Liquid-Liquid Interfacial Electron Transfer from Ferrocene to Gold(III): An Ultrasimple and Ultrafast Gold Nanoparticle Synthesis in Water under Ambient Conditions

Ferrocene (Fc) in ether reduces HAuCl4 in water within seconds under ambient conditions in air upon stirring, forming ferricinium chloride stabilized water-soluble 20 nm gold nanoparticles (AuNPs) that are redispersible in the presence of poly(N-vinylmethylpyrro-lidone) or NaBH4 + thiol. After reduction with NaBH4 yielding Fc and 26 nm sodium poly(hydroxyborate) stabilized AuNPs, the core size no longer changes following reactions with thiols providing (RS)(n)AuNPs.