Self-assembling behaviour of new functional photosensitive cinnamoyl-based reactive mesogens

One of the most exciting classes of organic materials that is able to self-assemble at nanoscopic scale are those exhibiting the liquid crystalline (LC) behaviour which can be distantly tuned by an external stimulus. Under UV/Vis light irradiation, the reversible photoisomerisation process can take place if the compounds possess the photosensitive group, e.g. N=N or cinnamoyl group incorporated in their molecular structure. This can drastically affect the LC behaviour. However, the compounds possessing the cinnamoyl fragment with C=C double bond are capable of both photoisomerisation and photocycloaddition processes. Several cinnamoyl-based reactive mesogens with polymerisable vinyl group have been designed; their mesomorphic and structural behaviour have been studied. Depending on the molecular structure, the reactive mesogens exhibit nematic, orthogonal smectic A and tilted smectic C phases; the kinetics of the phase transition temperatures has been checked. The structure of the mesophases is confirmed by small-angle X-ray scattering. The main objective of the present work is to contribute to better understanding of molecular structure–mesomorphic property relationship for new functional cinnamoyl-based photosensitive reactive mesogens which can be further used for design of smart self-assembling macromolecular materials.