title: Ionic liquids of bis(alkylethylenediamine)silver(I) salts and the formation of silver(0) nanoparticles from the ionic liquid system.
abstract: We have prepared novel ionic liquids of bis(N-2-ethylhexylethylenediamine)silver(I) nitrate ([Ag(eth-hex-en)(2)]NO(3) and bis(N-hexylethylenediamine)silver(I) hexafluorophosphate ([Ag(hex-en)(2)]PF(6)), which have transition points at -54 and -6 degrees C, respectively. Below these transition temperatures, both the silver complexes assume amorphous states, in which the extent of the vitrification is larger for the eth-hex-en complex than for the hex-en complex. The diffusion coefficients of both the complex cations, measured between 30 (or 35) and 70 degrees C, are largely dependent on temperature; the dependence is particularly large in the case of the eth-hex-en complex cation below 40 degrees C. Small-angle X-ray scattering studies showed that the bilayer structure of the metal complex is formed in the liquid state for both the silver complexes. A direct observation of the yellowish [Ag(eth-hex-en)(2)]NO(3) liquid by transmission electron microscopy (TEM) indicates the presence of nanostructures, as a microemulsion, of less than 5 nm. Such structures were not clearly observed in the [Ag(hex-en)(2)]PF(6) liquid. Although the [Ag(eth-hex-en)(2)]NO(3) liquid is sparingly soluble in bulk water, it readily incorporates a small amount of water up to [water]/[metal complex] = 7:1. Homogeneous and uniformly sized silver(0) nanoparticles in water were created by the reduction of the [Ag(eth-hex-en)(2)]NO(3) liquid with aqueous NaBH(4), whereas silver(0) nanoparticles were not formed from the [Ag(hex-en)(2)]PF(6) liquid in the same way.
authors.affiliation: Department of Chemistry, Nara Women's University, Kita-uoya-nishi-machi, Nara 630-8506, Japan. iida@cc.nara-wu.ac.jp
authors.forename: Masayasu
authors.initials: M
authors.lastname: Iida
authors.forename: Chihiro
authors.initials: C
authors.lastname: Baba
authors.forename: Michiko
authors.initials: M
authors.lastname: Inoue
authors.forename: Hibiki
authors.initials: H
authors.lastname: Yoshida
authors.forename: Eiji
authors.initials: E
authors.lastname: Taguchi
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Furusho