Pellechia Perry J, Gao Jinxin, Gu Yunlong, Ploehn Harry J, Murphy Catherine J
Department of Chemistry and Biochemistry, 631 Sumter Street, University of South Carolina, Columbia, South Carolina 29208, USA.
Inorg Chem. 2004 Feb 23;43(4):1421-8. doi: 10.1021/ic035127e.
The reaction of generation 2 and generation 4 poly(amidoamine) (PAMAM) dendrimers with K2PtCl2 was studied by several NMR methods. The time dependency of the Pt(II) complexation was followed with 195Pt NMR for both dendrimers and the equilibrium product was further characterized with (1)H NMR, and indirectly detected 13C NMR, in the case of the generation 2 dendrimer. After 2 days, a black precipitate of Pt(0) was observed, half the original 195Pt signal was lost, and approximately 20% of the initial Pt(II) was coordinated to the tertiary and secondary nitrogens of the generation 2 dendrimer. The uptake of Pt(II) by the generation 4 dendrimer was much slower, consistent with the steric crowding of the surface groups on the generation 4 dendrimer compared to the more open generation 2. After 10 days, 80% of the Pt(II) was deep within the generation 4 dendrimer; the remaining 20% was unreacted or bound near the surface nitrogens of a single dendrimer. The location and time course of the platinum ion uptake by the dendrimers provides valuable insight into the formation of Pt(0) nanoparticles made in the presence of dendrimers as stabilizers, visualized by atomic force microscopy.
采用多种核磁共振方法研究了第二代和第四代聚（酰胺胺）（PAMAM）树枝状大分子与K2PtCl2的反应。通过195Pt NMR跟踪了两种树枝状大分子中Pt（II）络合的时间依赖性，并用1H NMR对平衡产物进行了进一步表征，对于第二代树枝状大分子，还间接检测了13C NMR。两天后，观察到黑色的Pt（0）沉淀，原始195Pt信号损失了一半，并且约20%的初始Pt（II）与第二代树枝状大分子的叔氮和仲氮配位。第四代树枝状大分子对Pt（II）的摄取要慢得多，这与第四代树枝状大分子表面基团的空间拥挤有关，相比之下第二代的结构更为开放。10天后，80%的Pt（II）深入到第四代树枝状大分子内部；其余20%未反应或结合在单个树枝状大分子表面氮附近。树枝状大分子对铂离子的摄取位置和时间进程为在树枝状大分子作为稳定剂存在的情况下形成的Pt（0）纳米颗粒的形成提供了有价值的见解，这通过原子力显微镜得以观察。
