Book Description

Liquid crystals (LCs) show unique optical and physical properties, and so these compounds are attractive for many applications, including displays, sensors, reconfigurable mirrors, photonic devices, etc. [1-5]. Due to the cost and performance limitations of devices based on existing LC materials, it is essential to develop novel systems that are cost-effective and with enhanced performance. Also, it is crucial to explore the properties of these soft matter materials with respect to the molecular modifications to better understand their broad applicability. This is especially the case if the phase types involved are recently discovered. Many chiral dopants required for cholesteric preparations are either obtained from conventional chemical synthesis or from plant extracts. So, in search for novel dopants which are of biological origin and are relatively cheaper to produce in large volume, a study has been carried out to develop chiral compounds made from the fermentation derived bio-precursors. Likewise, the recently discovered nematic ferroelectric (NF) LCs [6] have not yet gained practical utility though they have potential to be applied in next generation displays and optoelectronic devices. Although these NF LCs show response towards ultra-small driving voltage ~1V/cm [7], the realistic applications are limited due to their current shortcomings such as monotropic LC phase, high temperature phase transition, thermochemical instability, etc. Thus, to develop novel improved systems and to seek their pragmatic applications, a variety of unique NF LCs have been synthesized and studied. Similarly, to explore the synthetic challenges and the properties related to their structural features, several classic compounds such as cyanobiphenyls (CBs), CB dimers, and triphenylene discotics have been prepared and examined. Reference: [1]Geelhaar, T. Liquid Crystals for Display Applications. Liq. Cryst. 1998, 24 (1), 91-98. https://doi.org/10.1080/026782998207613. [2] White, T. J.; Freer, A. S.; Tabiryan, N. V.; Bunning, T. J. Photoinduced Broadening of Cholesteric Liquid Crystal Reflectors. J. Appl. Phys. 2010, 107 (7). https://doi.org/10.1063/1.3369437. [3] Sergeyev, S.; Pisula, W.; Geerts, Y. H. Discotic Liquid Crystals: A New Generation of Organic Semiconductors. Chem. Soc. Rev. 2007, 36 (12), 1902-1929. https://doi.org/10.1039/b417320c. [4] Kumar, M.; Kumar, S. Liquid Crystals in Photovoltaics : A New Generation of Organic Photovoltaics. 2017, No. July 2016, 85-111. https://doi.org/10.1038/pj.2016.109. [5] Beeckman, J. Liquid-Crystal Photonic Applications. Opt. Eng. 2011, 50 (8), 081202. https://doi.org/10.1117/1.3565046. [6] Chen, X.; Chen, X.; Korblova, E.; Korblova, E.; Dong, D.; Dong, D.; Wei, X.; Wei, X.; Shao, R.; Shao, R.; et al. First-Principles Experimental Demonstration of Ferroelectricity in a Thermotropic Nematic Liquid Crystal: Polar Domains and Striking Electro-Optics. Proc. Natl. Acad. Sci. U. S. A. 2020, 117 (25), 14021-14031. https://doi.org/10.1073/pnas.2002290117. [7] Nishikawa, H.; Shiroshita, K.; Higuchi, H.; Okumura, Y.; Haseba, Y.; Yamamoto, S. I.; Sago, K.; Kikuchi, H. A Fluid Liquid-Crystal Material with Highly Polar Order. Adv. Mater. 2017, 29 (43), 1-8. https://doi.org/10.1002/adma.201702354.