Zhang Jing, Liu Hua-Ji, Yuan Yuan, Jiang Songzi, Yao Yefeng, Chen Yu
Department of Chemistry, School of Sciences, Tianjin University, Tianjin 300072, People's Republic of China.
Department of Physics & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, North Zhongshan Road 3663, Shanghai 200062, People's Republic of China.
ACS Macro Lett. 2013 Jan 15;2(1):67-71. doi: 10.1021/mz300613q. Epub 2012 Dec 28.
Hyperbranched polyethylenimine terminated with isobutyramide groups (HPEI-IBAm) was mixed with 4-(phenylazo)benzoic acid (PABA) to form supramolecular complexes through the neutralization reaction between the amino groups of HPEI-IBAm and the carboxylic acid group of PABA, which was verified by H and 2D NOESY H NMR spectroscopy. The obtained supramolecular complexes with a molar ratio of PABA to HPEI-IBAm of ≤8 were soluble in water and exhibited thermoresponsive properties. Their cloud point temperature () was sensitive to PABA content, and PABA molecules were exchanged between HPEI-IBAm hosts. The topology of the polymer affected the change in of the complexes. At pH ∼7, increasing the PABA content decreased , whereas it caused to increase at pH ∼9. Reversible -to- photoisomerization of azobenzene units in the complexes occurred following irradiation with UV or visible light. At pH ∼7, -to- isomerization of azobenzene units increased , whereas the opposite occurred at pH ∼9.
将末端带有异丁酰胺基团的超支化聚乙烯亚胺（HPEI-IBAm）与4-（苯基偶氮）苯甲酸（PABA）混合，通过HPEI-IBAm的氨基与PABA的羧酸基团之间的中和反应形成超分子复合物，这通过氢核磁共振光谱（1H NMR）和二维NOESY氢核磁共振光谱（2D NOESY 1H NMR）得到证实。所获得的PABA与HPEI-IBAm摩尔比≤8的超分子复合物可溶于水并表现出热响应特性。它们的浊点温度（）对PABA含量敏感，并且PABA分子在HPEI-IBAm主体之间进行交换。聚合物的拓扑结构影响复合物的变化。在pH约为7时，增加PABA含量会降低，而在pH约为9时则会导致升高。复合物中的偶氮苯单元在紫外光或可见光照射后发生可逆的顺反异构化。在pH约为7时，偶氮苯单元的顺反异构化增加，而在pH约为9时则相反。
