小尺寸铕(Ⅲ)配合物荧光纳米颗粒的制备

Preparation of Small-sized Luminescent Eu ^(3+) Chelate Nanoparticles

利用再沉淀法分别制备出了小尺寸(~10nm)纯相和杂相的Eu3+配合物荧光纳米颗粒。所制备的纯相的荧光纳米颗粒在水溶液中容易聚集,并且荧光猝灭严重。相比较而言,掺有适量疏水性硅烷的杂相纳米颗粒则具有较强的荧光、均匀的尺寸和良好的分散性。硅烷在碱性环境下(pH=9)迅速地水解,而后在纳米微粒的表面形成二氧化硅薄层。亲水的二氧化硅薄层消除了Eu3+配合物纳米颗粒间的疏水相互作用,进而防止了纳米颗粒的聚集,从而导致了杂相荧光纳米颗粒发光性能的提高。

DT-Eu^3＋ and DT-Eu^3＋· OTS nanoparticles （NPs） are prepared by reprecipitation under sonication. The two kinds of fluorescent NPs are both of small size,- 10 nm in diameter. But aggregation and greatly weakened luminescence of the pure chelate＇ NPs disable them as fluorescent probes. With the introduction of appropriate hydrophobic silane, for example with 1 ： 5 ratio of DT-Eu^3 ＋ chelate to OTS, the hybrid chelate NPs have intensive luminescence, uniform size and are well dispersed. Such improvements originate from the outside silica layer, which is developed from the rapid hydrolysis of alkoxysilane under basic environment （pH = 9）. The hydrated silica layer eliminates the hydrophobic interaction then aggregation, and isolates DT-Eu^3＋ chelate from water molecules. Formation details of Eu^3＋ chelate NPs via reprecipitation are revealed by the time-dependent absorption and luminescence behaviors of fresh-prepared suspensions. Evenly distributed microjets are assumed as precursors of NPs, which evolve from a loose structure to a compact one with the diffusion of THF. With the exhaustion of THF, NPs are resulted.