Synthesis of Cyano-Bridged Magnetic Nanoparticles Using Room-Temperature Ionic Liquids

摘要

A principally new exploit of ionic liquids as an alternative reaction medium in the synthesis of cyanobridged coordination-polymer nanoparticles is reported.Stable colloid solutions containing nanoparticles of cyano-bridged molecule-based magnets,M_3[Fe(CN)_6]_2/[RMIM][BF_4](M~(2+)=Ni, Cu, Co)and Fe_4[Fe(CN)_6]_3/[RMIM][BF_4](R=1-butyl(BMIM),1-decyl(DMIM)),were prepared in the corresponding 1-R-3-methylimidazolium tetrafluoroborate [RMIM][BF_4],which acts as both a stabilising agent and a solvent.By varying the length of the N-alkyl chain on the imidazolium cation of [RMIM]~+ andthe temperature,the growing process can be controlled to produce nanoparticles of different sizes.By studying the magnetic properties of frozen colloids it is shown that the relaxation of magnetisation is strongly influenced by in-terparticle interactions,which leads to the appearance of spin-glass-like dynamics in these systems.