奇偶效应诱导的苯丙氨酸类水凝胶手性反转  

Inversion of Supramolecular Chirality of Nanofibrous Structures Tuned by the Odd-Even Effects among Bis-amide and Bis-urea

作　　者：刘进营 秦明高 Dang-i Y. Auphedeous 刘志伟 窦晓秋[1] 冯传良[1] 

机构地区：[1]金属基复合材料国家重点实验室上海交通大学材料科学与工程学院,上海200240 [2]金属基复合材料国家重点实验室上海交通大学化学化工学院,上海200240

出　　处：《高分子学报》2018年第1期80-89,共10页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号51573092,51273111); 上海市教育委员会科研创新计划重大项目; 上海高校特聘教授(东方学者)岗位计划资助

摘　　要：为了模拟生物大分子(如DNA和蛋白质等)螺旋手性反转的现象,设计合成了4种酰胺基或脲基共价连接L-苯丙氨酸和苯环,外围为二甘醇胺与3-氨基-1,2-丙二醇的C2对称小分子凝胶因子,利用酰胺基(CONH)与脲基(NHCONH)之间的奇偶效应实现了超分子螺旋手性的反转.通过核磁共振波谱仪(1H-NMR和13C-NMR),高分辨质谱仪(HRMS)对凝胶因子结构和分子量进行了分析表征.并运用圆二色光谱(CD)、扫描电子显微镜(SEM)、紫外可见吸收光谱(UV-Vis)和红外光谱(FTIR)对其组装纤维结构和组装方式进行研究.实验结果表明酰胺基(CONH)与脲基(NHCONH)之间的奇偶效应改变凝胶因子的组装方式,调控了超分子手性特征,实现了超分子水凝胶螺旋手性的反转.Helicity inversion of biomacromolecules（e.g., DNA or proteins） is a sophisticated ubiquitous phenomenon in many physiological pr℃esses and ass℃iated with specific bio-functions. Therefore, designing of smart systems, with tunable helical chirality and further promoting their applications in the fields of bi℃hemistry, biology and nano-materials, has become appealing. In this regard, four novel C2-symmetric small-molecule gelators, with L-phenylalanine and benzene ring as skeletons covalently linked by amide group（CONH） or urea group（NHCONH）, are designed and synthesized. Based on the odd-even effect between the amide group（CONH） and the urea group（NHCONH）, the chiral reversal of the supramolecular assembly can be regulated. The structures of the compound, a-BDFAE, u-BDFAE, a-BDFAP and u-BDFAP, were confirmed by hydrogen-1 nuclear magnetic resonance（1 H-NMR）, carbon-13 nuclear magnetic resonance（13 C-NMR） and high resolution mass spectrum（HRMS）. The hydrogels were characterized using circular dichroism spectrum（CD）, and they all exhibited bisignate CD effect. However, the sign and intensity were inverted between the amide and urea molecules. The microstructure of the samples was studied using the scanning electron microscopy（SEM）. They all assembled into fine nanofibers with diameter in the range of tens of micrometers. The aggregation pattern of the gelators was also investigated with a UV-Vis spectroscopy in different solvents from non-gelating（ethanol） to gelating（water）. Amide molecules showed a broad band at around 241 nm in ethanol, which was red-shifted to 245 nm with the solvent changed to milli-Q water. This red-shift clearly indicates the J-type aggregation pattern of the amide hydrogelators. While the UV-Vis spectroscopy of the urea molecules showed a blue-shift, suggesting that the urea molecules formed H aggregates, a different mode of self-assembly induced by the inversion of the supramolecular chirality of amide and urea hydrogels. The interaction

关 键 词：水凝胶 奇偶效应 超分子手性反转 酰胺键 脲基 

分 类 号：O648.17[理学—物理化学]