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ABSTRACT
Two novel chiral fluorescent photoswitches bearing unsymmetric α-cyanothienylethene as emissive/photosensitive scaffold and bridged binaphthyl moieties as chiral entities are synthesised. The effects of the position of cyano group in switch 8 and 9 on the photoluminescence and photoresponsive properties of them in organic solvent and cholesteric liquid crystals (Ch-LCs) are explored. Both of these two photoswitches undergo partial reversible Z/E photoisomerisation accompanied by changes in fluorescence intensity under the light irradiations in both organic solvent and LC media. However, fluorescence quantum yields of switch 8 are much higher than those of switch 9. Meanwhile, the initial helical twisting power (HTP) value of switch 8 in LC media is much higher than that of switch 9, which is ascribed to their distinct geometries arising from different positions of cyano group on the C=C bond in them. Moreover, the switch 8-doping Ch-LC system exhibits more fast response and better reversible switching behaviours compared to Ch-LC system containing switch 9. Finally, simultaneous photoswitching of the reflection colour and fluorescence intensity in the Ch-LC sample is demonstrated. This work provides an idea for designing chiral fluorescent photoswitches with advanced photoluminescence and photoswitching characteristics.
GRAPHICAL ABSTRACT
Acknowledgments
The authors acknowledge the supports from the National Natural Science Foundation of China (Grant Nos. 51773009 and 52073017). This work is supported by the High Performance Computing Platform of Beijing University of Chemical Technology.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Supplementary materials
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