Fluorescent liquid crystal materials combine the anisotropic self-assembly properties of liquid crystals with luminescent functionality. As an important class of organic luminescent materials, fluorescent liquid crystal materials with precisely tunable luminescent colors have attracted special attention from researchers. However, the control of the luminescent properties of fluorescent liquid crystal materials is still largely limited by the chemical structure of the fluorescent liquid crystal building blocks. While changes in conformation or assembly structure of liquid crystal molecules can modify solid-state luminescent colors through external stimuli, the strong reliance of fluorescent emission on aggregate structure poses challenges in constructing liquid crystal materials with precise control over tunable luminescent colors. Therefore, the development of fluorescent liquid crystal materials with precisely adjustable luminescent colors, while ensuring meticulous control over the chemical structure and stacking mode of the building blocks, holds significant scientific and practical value.

   Recently, our research group successfully constructed a class of liquid crystal polymers with continuously tunable fluorescent colors through a copolymerization reaction mediated by positional isomers of cyanostyrene. Due to the similar chemical structures of the two positional isomers of cyanostyrene, the copolymerization process does not result in heterogeneity in the polymer assembly structure, allowing for the formation of a uniform hexagonal columnar liquid crystal structure through molecularly ordered co-assembly. The positional isomerism of the cyanostyrene induces significant differences in fluorescence between the two monomers, enabling continuous variation of the luminescent color of the liquid crystal polymer from blue to green by changing the molar ratio of the two monomers during copolymerization. Additionally, based on the unique photochemical reactivity of cyanostyrene building blocks, the liquid crystal polymers of this type can undergo reversible [2+2] cycloaddition reactions under irradiation from UV lamps of different wavelengths, accompanied by significant changes in fluorescence color and intensity. Therefore, they exhibit great potential in applications such as fluorescent erasable devices.

The relevant research findings were published in "Macromolecules" (2022, DOI 10.1021/acs.macromol.2c00458).

Associate Professor Bin Mu from our research group is the first author of the paper, and

Professor Wei Tian is the corresponding author.

(Full article link: https://pubs.acs.org/doi/10.1021/acs.macromol.2c00458)