Universität Würzburg, Institut für Organische Chemie and Center for Nanosystems Chemistry, Am Hubland, 97074 Würzburg, Germany.
Chemistry. 2013 Mar 25;19(13):4176-83. doi: 10.1002/chem.201204146. Epub 2013 Feb 11.
The self-assembly behavior of an achiral perylene bisimide (PBI) organogelator that bears two 3,4,5-tridodecyloxybenzoylaminoethyl substituents at the imide positions has been investigated in chiral solvents (R)- and (S)-limonene in great detail by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). CD spectroscopic studies on dilute solutions revealed a preferential population of one-handed helical assemblies in chiral solvent with an enantiomeric excess close to 100 %, whereas AFM images of more than 100 nanofibers of the organogel obtained from more concentrated solutions were found to consist of both handed helices with an enantiomeric excess of only 20 %. This discrepancy is attributed to the fast gelation process at high dye concentration that evidently proceeds through non-equilibrated nuclei in a kinetic rather than thermodynamic self-assembly process. Under these conditions the chiral induction from the homochiral solvent may not be adequate in effectively populating only one-handed helices.
手性溶剂（R）-和（S）-柠檬烯中，具有两个 3,4,5-三正十二烷氧基苯甲酰基乙氨基取代基的非手性苝二酰亚胺（PBI）有机凝胶剂的自组装行为通过圆二色性（CD）光谱和原子力显微镜（AFM）进行了详细研究。在稀溶液中的 CD 光谱研究表明，在具有接近 100%对映过量的手性溶剂中，优先存在单手螺旋组装体，而从浓度更高的溶液中获得的有机凝胶的 100 多个以上纳米纤维的 AFM 图像则发现由两种手性螺旋组成，对映过量仅为 20%。这种差异归因于高染料浓度下快速凝胶化过程，显然是通过非平衡核在动力学而非热力学自组装过程中进行的。在这些条件下，来自同手性溶剂的手性诱导可能不足以有效地填充单手螺旋。
