Luminescent Ag<SUB>7</SUB> and Ag<SUB>8</SUB> clusters by interfacial synthesis

Interfacial etching of silver nanoparticles and separation of the products by polyacrylamide gel electrophoresis afforded Ag8 and Ag7 clusters with red and blue-green fluorescence emission, respectively (see picture). The strongly temperature-dependent emission of the clusters suggests potential applications, whilst their facile phase transfer to organic media facilitates further studies

Interfacial synthesis of luminescent 7 kDa silver clusters

We report the synthesis of luminescent Ag clusters through the interfacial etching of mercaptosuccinic acid (MSA) protected silver nanoparticles, Ag@MSA, with guanine at the water-toluene interface. The clusters exhibiting well-defined absorption emit in the near-infrared (NIR) region. Crude clusters were separated using polyacrylamide gel electrophoresis (PAGE). The cluster solid, prepared by freeze drying, is highly hygroscopic. Biomolecular markers were used to identify the approximate mass of the cluster which was found to be 7 kDa, as mass spectrometry did not reveal specific signatures. The clusters were investigated using UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and fluorescence spectroscopy. Elemental analysis and IR studies reveal the protection of the cluster by two types of ligands, namely MSA and guanine. Fluorescence of the cluster is highly temperature dependent, with an increase in intensity with decrease in temperature. Influence of different ratios of reactants, etching capacity of different nucleobases and effect of temperature on the synthesis as well as possible single-phase etching were investigated. Sensitivity of the cluster to certain metal ions has been monitored using fluorescence spectroscopy

First principles studies of two luminescent molecular quantum clusters of silver, Ag<SUB>7</SUB>(H<SUB>2</SUB>MSA)<SUB>7</SUB> and Ag<SUB>8</SUB>(H<SUB>2</SUB>MSA)<SUB>8</SUB>, based on experimental fluorescence spectra

We report a joint experimental and theoretical study of two luminescent molecular quantum clusters of silver, Ag<SUB>7</SUB>(H<SUB>2</SUB>MSA)<SUB>7</SUB> and Ag<SUB>8</SUB>(H<SUB>2</SUB>MSA)<SUB>8</SUB> (H<SUB>2</SUB>MSA is the dicarboxylic acid of mercaptosuccinic acid in thiolate form). Global optimizations and property calculations are performed in the framework of density-functional theory (DFT-PBE) to search for the leading candidates with the lowest energy. The simulated excitation spectra of these two clusters are in good agreement with the corresponding experimental spectra. The presence of -RS-Ag-RS- as a stable motif has been confirmed in all of the lowest energy structures

Ultrasmall Ag+-rich nanoclusters as highly efficient nanoreservoirs for bacterial killing

10.1007/s12274-013-0395-6Nano Research73301-30