University of Warsaw, Department of Chemistry, ul. Żwirki i Wigury 101, 02-089, Warsaw, Poland.
Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska 160, 2000, Maribor, Slovenia.
Angew Chem Int Ed Engl. 2016 Mar 1;55(10):3468-72. doi: 10.1002/anie.201510123. Epub 2016 Feb 2.
Bent-core materials exhibiting lamellar crystals (B4 phase), when dissolved in organic solvents, formed gels with helical ribbons made of molecular monolayers and bilayers, whereas strongly deformed stacks of 5-6 layers were found in the bulk samples. The width and pitch of the helical filaments were governed by molecular length; they both increased with terminal-chain elongation. It was also found that bulk samples were optically active, in contrast to the corresponding gels, which lacked optical activity. The optical activity of samples originated from the internal structure of the crystal layers rather than from the helicity of the filaments. A theoretical model predicts a strong increase in optical activity as the number of layers in the stack increases and its saturation for few layers, thus explaining the smaller optical activity for gels than for bulk samples. A strong increase and redshift in fluorescence was detected in gels as compared to the sol state.
表现为层状晶体（B4 相）的弯曲核材料，当其溶解在有机溶剂中时，形成由分子单层和双层组成的螺旋带状凝胶，而在块状样品中则发现了强烈变形的 5-6 层堆积。螺旋纤维的宽度和螺距受分子长度的控制；它们都随着末端链的延长而增加。还发现，与相应的凝胶相比，块状样品具有光学活性，而凝胶则没有光学活性。样品的旋光性来源于晶体层的内部结构，而不是纤维的螺旋性。理论模型预测，随着堆积层数的增加，旋光性会强烈增加，并在少数层达到饱和，因此解释了凝胶的旋光性比块状样品小的原因。与溶液状态相比，凝胶中的荧光强度显著增加且红移。
