Baghla Anshika, Sahai Mudit, Yadav Neelam, Gupta Santosh Prasad, Punjani Vidhika, Manjuladevi V, Vij Jagdish K, Pal Santanu Kumar
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali Sector-81 Knowledge City Manauli 140306 India
Department of Electronic and Electrical Engineering, Trinity College Dublin, The University of Dublin Dublin 2 Ireland
Chem Sci. 2025 Mar 20;16(18):8002-8013. doi: 10.1039/d5sc01530h. eCollection 2025 May 7.
The growing demand for advanced photonic and electro-optical devices necessitates the rational design of novel functional materials. Liquid crystals (LCs) are particularly promising due to their highly tunable electro-optical properties. Building on this potential, we synthesized a series of polar bent-core LCs, F4-a (dipole moment ∼9.4 D), featuring a tetrafluorinated terminal motif and varying terminal chains. Distinct structure-property relationships are observed in this series of compounds, with the shorter chain homologues forming polar cybotactic clusters (N phase) alongside nematic and tilted smectic phases. Dielectric spectroscopy reveals non-trivial dipolar ordering, attributed to short-range polar order within cybotactic clusters, notably present without net macroscopic polarization. Under an AC field, the materials form electroconvection patterns, suggesting potential for optical modulation devices. Furthermore, the F4-a materials, particularly the lower homologues showing cybotactic clusters, stabilize the otherwise unstable blue phase (BP) at room temperature when doped with a chiral additive, achieving a maximum BP range of 22.9 °C. This overcomes the challenges in achieving room-temperature BP with our easily synthesizable materials, holding strong potential for 3D photonic applications. Overall, our findings offer promising opportunities for advancing room-temperature photonic and electro-optical devices while enhancing the understanding of self-assembly in soft functional materials.
对先进光子和电光器件日益增长的需求使得新型功能材料的合理设计成为必要。液晶（LCs）因其高度可调的电光特性而特别有前景。基于这一潜力，我们合成了一系列极性弯曲核液晶F4-a（偶极矩约为9.4 D），其具有四氟化末端基序和不同的末端链。在这一系列化合物中观察到了不同的结构-性能关系，较短链的同系物除了向列相和倾斜近晶相之外还形成了极性群聚态簇（N相）。介电谱揭示了非平凡的偶极有序，这归因于群聚态簇内的短程极性有序，特别是在没有净宏观极化的情况下显著存在。在交流电场下，这些材料形成电对流图案，表明其在光调制器件方面具有潜力。此外，F4-a材料，特别是显示群聚态簇的较低同系物，在掺杂手性添加剂时在室温下稳定了原本不稳定的蓝相（BP），实现了最大22.9 °C的蓝相温度范围。这克服了用我们易于合成的材料实现室温蓝相的挑战，在三维光子应用方面具有巨大潜力。总体而言，我们的发现为推进室温光子和电光器件提供了有前景的机会，同时增进了对软功能材料中自组装的理解。
