Perspective on structure-property relationship of room temperature single-component liquid crystals

Ever since the serendipitous discovery of liquid crystals (LC) by Friedrich Reinitzer in 1888, a significant number of LCs have been synthesised and characterised. The ever-growing LCs emanating from conventional and non-conventional systems find applications in various electronic appliances such as flat-panel TV displays, notebooks, digital cameras, and domestic devices. The room temperature LCs (RT-LCs 20 to ±80 °C), either as single-component/composites, act as a starting point for such applications. Therefore, the quest for such RT-LCs is always valued and carved out as a promising niche for many such devices. Molecular design and the structure-property relationship are the recurrent themes for stable and single-component RT-LCs. The LC molecules starting from simple benzenoids to macrocycles with flexible hydrocarbon chains as spacer/terminal tails needed to be tethered in a precise pattern may lead to potential LCs. To craft stable and single-component RT-LCs, functional groups (nitrile, halogens, nitro, aldehydes, amine, thiol, alcohol, ketone, ester, amide) are frequently employed. RT-LCs with viscosity, dielectric, birefringence, and polarity enables the reduction of the number of components in a composites mixture. This review describes the genesis and importance of the single component RT-LCs, state-of-the-art LC research, perspectives, and new design strategies for venturing into a new horizon.