Ag₂ and Ag₃ Clusters: Synthesis, Characterization, and Interaction with DNA

Abstract

Subnanometric samples, containing exclusively Ag2 and Ag3 clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag3 clusters interact with DNA through intercalation, inducing significant structural distortion to the DNA. The lifetime of Ag3 clusters in the intercalated position is two to three orders of magnitude longer than for classical organic intercalators, such as ethidium bromide or proflavine.

Self-Assembly of Silver Metal Clusters of Small Atomicity on Cyclic Peptide Nanotubes

“…36 In addition, the high stability of these low atomicity Ag clusters under the typical experimental conditions used in this work (aqueous dispersion at room temperature) have been recently clearly established. 34 DFT calculations have confirmed three equivalent C 2v obtuse isosceles triangle minimum geometries for the molecular shape of Ag 3 clusters. 29,37,38 This configuration yields triangular clusters of three silver atoms without net charge.…”

“…29 Silver clusters dispersed in water were prepared by a modified electrochemical protocol and they were free of any ligand and Ag + ions. [2][3][4]7,9,10,22,34 The absence of Ag + ions, achieved by precipitation (AgCl), produces highly stable clusters dispersions under standard conditions (aqueous solutions, room temperature). 4,34 The UV absorbance and fluorescence emission spectra of these cluster dispersions is shown in Fig.…”

“…Furthermore, the intercalation of silver clusters within DNA 7 double helices has been postulated and studied by UV spectroscopy. 17,34 However, non-covalent interactions of molecular metal clusters of zero valence have not been seen at work. The results reported here highlight the importance that supramolecular chemistry and non-covalent interactions will play in the emerging field of subnanometric metal (0) clusters.…”

“…It is important to note that the same kind of interactions could be operative and therefore applicable to other silver clusters of small atomicity. 14,15,34 Complementary to the central importance of synthetic protocols, the supramolecular and non-covalent chemistry of SNMCs will enable innovative approaches to be developed for the characterization, manipulation and application of these promising molecular metal clusters.…”

The wet synthesis and quantification of ligand-free sub-nanometric Au clusters in solid matrices

“…7 In contrast to nanoparticles (NPs), the small size of the cluster pinpoints all the metal atoms on surface and enables high accessibility to external reagents, provided that strong ligands do not cover the surface. 8 However, the bottleneck for a general use of ligand-free small metal clusters in any application is their synthesis and storage for long periods.…”