Uncommon building blocks in liquid crystals

Abstract

Just as nematic liquid crystals are widespread in display technology, a small number of building blocks find widespread use in the design and synthesis of liquid crystalline materials. This review explores the intricate relationship between the molecular structure of thermotropic liquid crystals (LCs) and their phase behaviour, emphasising the role of specific structural fragments in determining LC properties. We also detail into the impact of non-conventional building blocks on LC properties by comparing families of materials differentiated by only a single structural variation, allowing us to probe the extent to which deviations from traditional structures can maintain liquid crystallinity. This comprehensive overview not only underscores the importance of specific molecular fragments in LC design but also opens avenues for the innovative use of non-traditional building blocks in the development of new LC materials. Just as the ubiquity of 1,4-disubstituted benzene rings has its genesis (partly) in the extremely robust and predictable synthesis of such systems through cross-coupling chemistry; we consider that, the rapid progress in coupling sp3 fragments, coupled with the growing availability of suitable building blocks, makes the inclusion of said fragments ever more practical and attractive for use in liquid crystalline systems.