低代端氨基树枝状大分子与Cu^(2+)的络合作用研究

STUDY ON COMPLEXATION BETWEEN LOW GENERATION AMINO-TERMINATED DENDRIMERS AND COPPER IONS

用紫外可见吸收光谱法研究低代端氨基树枝状大分子G1．0(NH2)3,G1．5(NH2)8和Cu2+之间的作用。与单组分溶液相比,Cu2+／树枝状大分子双组分溶液的紫外吸收光谱峰形变宽,最大吸收波长红移,吸光度增大,且出现了可见光区吸收,表明在水溶液中,低代端氨基树枝状大分子和Cu2+之间存在络合作用。随着Cu2+与树枝状大分子摩尔比或Cu2+浓度的增加,最大吸收波长红移,吸光度增大。pH值对络合有很大影响,酸性条件下可见光区吸收消失,说明Cu2+／树枝状大分子络合物解离。透射电镜照片显示Cu2+／G1．5 (NH2)8络合体系比Cu2+／G1．0(NH2)3络合体系更加均匀,而聚集体粒径较大。在较宽的浓度范围内,两体系都能稳定存放180 d以上。一个G1．0(NH2)3和G1．5(NH2)8分子最多分别能络合5和7个Cu2+。

UV-visible absorption spectrum was employed to study the interaction between low generation amino-terminated dendrimers G1. 0 （NH2）3, G1.5 （NH2）8 and Cu^2＋. Compared with single component solution, UV absorption spectra of Cu^2＋/ two-component aqueous dendrimer had redshift-maximum absorbing wavelengths, widening absorption peaks, and increasing absorbance. Moreover, visible absorption appeared, indicating that complexation between G1. 0 （NH2）3, G1.5 （NH2）8 and Cu^2＋ formed in the water solutions. When the molar ratio of Cu^2＋ to dendrimer or the concentration of Cu^2＋ rose, a red-shift of maximum absorbing wavelength and strengthening of the absorbance were observed. The pH value had great effects on the complexation. The visible absorption spectra disappeared under strong acid condition, implying that the complex of Cu^2＋/dendrimer broke. The transmission electron microscopy analysis results showed that the system of Cu^2＋/ G1.5 （NH2）8 was more uniform and the aggregates was larger than that of Cu^2＋/G1.0 （NH2）3. Both of the two Cu^2＋/dendrimers systems in a wide range of concentration could be kept stably for more than 180 days. The maximum number of Cu^2＋ bound by G1.0 （NH2）3 and G1.5 （NH2）8 was about 5 and 7, respectively.