树形聚酰胺胺与Cu^(2+)的络合作用

Spectrophotometric Study on the Complex Formation between Dendritic Polyamideamine Molecules and Cupric Ions

合成了4.0代聚酰胺胺 (PAMAM)树形分子 ,并合成出端基为羟基的PAMAM树形分子衍生物。用分光光度法研究了4.0代PAMAM树形分子及其衍生物与Cu2 +的络合作用。结果表明当存在树形聚酰胺胺分子时 ,Cu2 +水溶液的最大吸收波长显著紫移 ,随n(Cu2 +)/n(PAMAM)增加 ,最大吸收波长红移 ;PAMAM树形分子与Cu2 +的络合作用有多种形式 ,对端胺基树形分子主要存在Cu -N4 和Cu -N2 两种配位方式 ;对端羟基树形分子主要存在Cu -N2 的配位方式 ;随Cu2 +的加入 ,络合形式和各种络合形式的相对比例发生变化 ;pH对络合形式有较大影响;随代数的增加 ,树形分子所能络合Cu2 +的最大数目不断增加 。

Dendritic polyamideamine(PAMAM) molecules of the 4.0 generation and their hydroxyl _ terminated derivatives were synthesized. The coordination between cupric ions and the dendritic PAMAM molecules as well as their derivatives was investigated by the spectrophotometric method. The maximum absorbing wavelength of aqueous Cu2+ solution diminishes dramatically when dendritic PAMAM molecules are introduced. As the molar ratio of Cu2+/PAMAM increases, a red _ shift of the maximum absorbing wavelength was observed. Several kinds of complexes are formed between dendritic PAMAM molecules and Cu2+. Cu-N4 and Cu-N2 are the major coordination forms between Cu2+ and amine _ terminated dendritic PAMAM molecules, while Cu-N2 is the prevailing form for Cu2+ and hydroxyl _ terminated dendritic PAMAM molecules. As the molar ratio of Cu2+/PAMAM increases, the complex forms as well as the relative proportion of different forms change. The pH value also has a significant effect on the complex forms. The maximum number of Cu2+ that a NH2 _ terminated dendritic PAMAM molecule could bind increases as the generation of dendritic molecule increases. There is a little discrepancy between the theoretical and measured value.