Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases
Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases
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DOI：
10.1080/02678292.2017.1360954
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发表时间：
2017-01-01
期刊：
影响因子：
2.2
通讯作者：
Goodby, John W.
中科院分区：
文献类型：
--
作者：
Archbold, Craig T.;Mandle, Richard J.;Goodby, John W.
扭转-弯曲相（N-TB）最常见于具有大弯曲形状的材料：二聚体；bent-cores;bent-oligomers。我们之前已经提出，这种体系的弯曲角度有效地决定了N-TB相的相对热稳定性。然而，我们早期的论文依赖于单个能量最小构象的使用，因此未能捕获有关柔韧性和构象分布的任何信息。在目前的工作中，我们重新审视了我们的假设，并研究了第二组具有不同连接基团和间隔组成的二聚体。我们通过研究每种材料的构象景观，改进了我们早期的工作，允许确定平均弯曲角以及构象分布。我们观察到，N-TB相的稳定性不仅与玻尔兹曼加权平均弯曲角（而不仅仅是静态构象）密切相关，而且与构象的分布密切相关。在较小程度上，隔震器的灵活性显得很重要。最终，这项工作满足了理论处理和我们最初的实验研究，并证明了分子弯曲对N-TB相的重要性。
The twist-bend phase (N-TB) is most commonly observed in materials with a gross-bent shape: dimers; bent-cores; bent-oligomers. We had suggested previously that the bend-angle of such systems effectively dictates the relative thermal stability of the N-TB phase. However, our earlier paper relied on the use of a single energy-minimum conformer and so failed to capture any information about flexibility and conformational distribution. In the present work, we revisit our hypothesis and examine a second set of dimers with varying linking groups and spacer composition. We have improved on our earlier work by studying the conformational landscape of each material, allowing average bend-angles to be determined as well as the conformer distribution. We observe that the stability of the N-TB phase exhibits a strong dependence not only on the Boltzmann-weighted average bend-angle (rather than just a static conformer), but also on the distribution of conformers. To a lesser extent, the flexibility of the spacer appears important. Ultimately, this work satisfies both theoretical treatments and our initial experimental study and demonstrates the importance of molecular bend to the N-TB phase.[GRAPHICS].