Synthesis And Fluorescent Property Studies Of Ru （bpy）₂ （Phen-5-amine） Doped Silica Nanoparticles

Fluorescent technique has attracted growing interest due to its widely application in the field of chemical analysis, environmental monitoring and biological imaging in the past years. Fluorescence nanoparticles such as quantum dots, dye-doped nanoparticles and rare earth-based nanoparticles etc. are in widespread studied.Because of highly sensitivity and rapid response abilities of dye-doped silica nanoparticles, and chemical stable, water-soluble and nontoxic properties as host materials, fluorescence silica-based dye-doped nanoparticles are explored and investigated extensively. In this work, we successfully synthesized(2,2’-bipyridine)2-(1,10-phenanthrolin-5-amine) Ru(hexa?uorophosphate)2(noted as Ru(bpy)2(phen-5-amine)) doped silica nanoparticles with high brightness and stability by introducing ethanol or acetonitrile via the reverse microemulsion method.Furthermore, their fluorescence properties are investigated.1. We choose the complex Ru(bpy)2(phen-5-amine) as the dye, a series of dye-doped silica nanoparticles have been prepared by our modified reverse microemulsion method, introducing ethanol to reaction system. Through the electrostatic interaction between the positively charged amine of dyes and the negatively charged silica, the dyes can be effectively entrapped inside silica particles2. By introducing ethanol to reverse microemulsion synthesis system, the obtained dye-doped silica nanoparticles perform good monodispersity and controllable size. We can get increasing uniform particle size in the range of 50 nm to180 nm by increasing a certain amount of ethanol in the reaction process. Chemical analysis indicates that dye molecules are effectively entrapped inside nanoparticles.3. With the increasing amount of ethanol, the fluorescence emission intensity and relative brightness of nanoparticles are increased. The relative brightness of nanopartilces are greatly improved from 530 to 86900 by comparison with free dyemolecules. The dye in nanoparticles have not been aggregated. The fluorescence of high concentration dye-doped silica nanoparticles has not been quenched. By the protection of silica matrix, the dye molecules are prevented from contacting with chemicals in the surrounding environments, the photo stability of dyes is also improved when they are incorporated in silica matrix. The initial fluorescence intensity was decreased only by 5%~10% after 15 times excitation.4. Instead of ethanol, we use acetonitrile to entrap more dye molecules inside silica nanoparticles. With the increasing of acetonitrile, the fluorescence emission intensity is increased. The nanoparticles which size is in the range of 50 nm to 80 nm perform monodispersity and good photo stability. These results are the same as those from ethanol system. The fluorescence intensity is increased due to the increase of dye concentration. When the particle size is greater than 80 nm, the dimerization of dye molecules is detected and silica nanoparticles become quenching when the concentration of the dye increased largely.