Fiore Gina L, Klinkenberg Jessica L, Pfister Anne, Fraser Cassandra L
Department of Chemistry, University of Virginia, McCormick Road, P.O. Box 400319, Charlottesville, Virginia 22904-4319, USA.
Biomacromolecules. 2009 Jan 12;10(1):128-33. doi: 10.1021/bm800998g.
Spontaneous gel formation of iron(II) tris(bipyridine)-centered poly(ethylene glycol) methacrylate ([Fe{bpy(PEG-MA)2}3]2+) was observed without the addition of a cross-linking agent. BpyPEG2 macroligands were first modified with methacrylate groups using methacrylic anhydride and then combined with FeSO4 to produce [Fe{bpy(PEG-MA)2}3]SO4. End group analysis by 1H NMR spectroscopy verified quantitative methacrylation of the PEG hydroxyl chain ends. A series of experiments and control reactions were performed to investigate the conditions required for gel formation. Hydrogels of [Fe{bpy(PEG-MA)2}3]SO4 were produced both in the presence and in the absence of a photoinitiator. Controls using MA-PEG-MA also formed hydrogels in the presence of [Fe(bpy)3]2+; however, the addition of a radical scavenger, TEMPO, prevented formation of a polymer network, suggesting radical involvement. Treatment of preformed hydrogels of bpy(PEG-MA)2 with aqueous solutions of FeSO4, CuBr2, and CoCl2 also produced materials with color changes indicative of complexation.
观察到以三联吡啶合铁（II）为中心的聚甲基丙烯酸乙二醇酯（[Fe{bpy(PEG-MA)2}3]2+）在不添加交联剂的情况下自发形成凝胶。首先使用甲基丙烯酸酐将BpyPEG2大环配体用甲基丙烯酸酯基团进行修饰，然后与FeSO4结合生成[Fe{bpy(PEG-MA)2}3]SO4。通过1H NMR光谱进行的端基分析证实了PEG羟基链端的甲基丙烯酰化是定量的。进行了一系列实验和对照反应以研究形成凝胶所需的条件。[Fe{bpy(PEG-MA)2}3]SO4水凝胶在有光引发剂和无光引发剂的情况下均能产生。使用MA-PEG-MA的对照在[Fe(bpy)3]2+存在下也形成了水凝胶；然而，添加自由基清除剂TEMPO可阻止聚合物网络的形成，这表明有自由基参与。用FeSO4、CuBr2和CoCl2的水溶液处理预先形成的bpy(PEG-MA)2水凝胶也会产生具有颜色变化的材料，表明发生了络合作用。
