Spontaneous formation of highly dispersed spheroidal metallic silver nanoparticles in surfactant-free N,N-dimethylacetamide

• Published in: Synthetic metals 2011-08, Vol.161 (15), p.1517-1521
• Main Authors: da Costa, Luiz Pereira, Formiga, André Luiz Barboza, Mazali, Italo Odone, Sigoli, Fernando Aparecido
• Format: Article
• Language: English
• Subjects: Chemical synthesis methods; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dispersion; Electron affinity; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic structure of nanoscale materials : clusters, nanoparticles, nanotubes, and nanocrystals; Exact sciences and technology; Ionization; Materials science; Mathematical analysis; Methods of nanofabrication; N,N-Dimethylacetamide; Nanoparticles; Optical properties; Physics; Plasmon; Silver; Silver nanoparticles; Surface and interface electron states; UHF
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2011.04.018

► This work shows the preparation of highly dispersed spheroidal silver nanoparticles. ► The reaction was carried out in surfactant-free N,N-dimethylacetamide solution. The nanoparticles average size is smaller than that obtained in N,N-dimethyformamide. ► N,N-Dimethyformamide interacts more weakly with Ag(I) than does N,N-dimethylacetamide. ► The chemical interactions strengths have implications on nanoparticles stabilization. The present work describes a simple method for preparing highly dispersed spheroidal metallic silver nanoparticles in surfactant-free N,N-dimethylacetamide solution. The optical properties, shape and size of the metallic silver nanoparticles obtained in N,N-dimethylacetamide after different times of reaction were characterized using UV–vis absorption spectroscopy and transmission electron microscopy. The average size of the metallic silver nanoparticles is smaller than that obtained by the well established procedure using N,N-dimethyformamide. Using optimized geometries for N,N-dimethylacetamide and N,N-dimethyformamide, vertical ionization energies and electron affinities were calculated by means of the UHF/DFT calculations of cations and anions, respectively. The difference between ionization energies and electron affinities is higher for N,N-dimethyformamide indicating that it is a harder base than N,N-dimethylacetamide. Therefore, N,N-dimethyformamide probably interacts more weakly with Ag(I) ions than does N,N-dimethylacetamide. The strength of this chemical interaction has implications on the stabilization and dispersion of silver nanoparticles obtained in N,N-dimethylacetamide. The low cost, simple methodology may be used as a platform for further studies in surface-enhanced Raman spectroscopy as well as with other optical properties that depend on the surface plasmon resonance of metallic silver nanoparticles.