Novel Crown Ether-Capped Cationic Gold Nanoclusters in an Aqueous Medium and Their Single-Electron Charging Features

Abstract

On the basis of the formation of a noncovalent inclusion complex through crown ether-ammonium ion interaction, a new ligand, 18-crown-6-aminoethanethiol (18C6-AET), was predesigned and synthesized with a formation constant of 4.26 x 10(2) M(-1)s(-1) for the 1:1 noncovalent complex. Consequently, stable crown ether-protected gold nanoclusters were synthesized with 18C6-AET in an aqueous medium with a rate of formation of 3.688 x 10(-4) min(-1). The newly formed 18C6-AET-capped gold nanoclusters showed quantized double-layer charging, revealing their concentric capacitor structure, and effective cluster capacitance, C(CLU) was calculated to be 0.93 aF from the single-electron events. A larger C(CLU) in comparison to that of monolayer-protected gold clusters with longer chain lengths was attributed to a smaller ligand shell thickness as well as the cationic nature of the nanoclusters formed in an aqueous electrolyte medium.

A facile synthesis of silver nanoparticle with SERS and antimicrobial activity usingBacillus subtilisexopolysaccharides

“…Using the above mentioned data, the kinetics of the nanoparticle formation was calculated and was found to follow first-order rate kinetics (supplementary figure 1 b1-b3, online only). The rate constant K, was determined by fitting the exponential data to the firstorder rate kinetics equation [27,28]. ) was found to be above 0.9 for all the concentrations of EPS indicating a linear relationship between the EPS and the silver nanoparticle formation.…”