树枝形分子的合成及其对纳米硫化镉生长的控制

用发散法合成了以苯胺为核的不同代数的聚酰胺-胺(PAMAM)型树枝状分子，采用核磁共振仪(NMR)对它们的结构进行了鉴定。又以第4代PAMAM树形分子(G4.0)为模板，在树形分子空腔内原位合成了硫化镉(CdS)纳米粒子。通过改变Cd²⁺与G4.0树枝状分子的摩尔比可以得到不同粒径的CdS量子点，并对其光学性能进行了表征。探讨了溶剂对CdS半导体纳米粒子在PAMAM模板中生长的影响。用UV-visible分光光度计和TEM对CdS纳米簇的大小和形貌进行了表征。结果表明TEM 观测的CdS纳米簇粒径要大于用Brus公式估算的数值。

Synthesis of a polyamidoamine dendrimer and the preparation of CdS/polyamidoamine dendrimer nanocomposites

A series of polyamidoamine(PAMAM) dendrimers with an aniline amino group at the center have been prepared through repetitive Michael addition and amidation reactions.Their structures were characterized by 1H NMR spectroscopy.Welldispersed CdS quantum dots(QDs) with narrow size-distribution were prepared using generation 4.0(G4.0) amine-terminated PAMAM dendrimers as the template.A series of CdS/PAMAM dendrimer nanocomposites with different diameters were prepared by addition of Na2S to a methanol solution of Cd2 /PAMAM complexes with different Cd2 /PAMAM ratios.The resulting CdS/PAMAM nanocomposites were characterized by UV-visible and photoluminescence spectrophotometry and TEM.The stability,diameter and dispersion of the CdS clusters were found to be significantly affected by varying the ratio of Cd2 to G4.0 PAMAM dendrimer.The results also showed that the dispersion of CdS/PAMAM nanocomposites was better and the diameters were larger when glycerine was used as the solvent in place of methanol.