Towards high contrast photochromism materials via fluorinated TPE-based medium ring.

A series of novel fluorinated tetraphenylethylene (TPE)-based 8–10 membered medium ring compounds with photochromic characters and mechanofluorochromic (MFC) features were concisely synthesized. These solid powder of 8, 9 and 10 members fluorinated TPE-based medium ring, 441F , 461F and 481F all exhibited photochromic character, comparing with their alkyl analogues. Notably, the solid powder of 441F displayed an intuitively evident crimson after ultraviolet (UV) irradiation and then reversed identical to its original white color within 42 s. Furthermore, the various photochromic abilities and stimuli responsive fluorescence of these compounds could be regulated by fluorinated loops' size. Such fast responsive and high-contrasted of photo switchable color of 441F promise candidate for photochromic materials. A series of novel fluorinated cyclic TPE with integration of AIE properties, reversed MFC features and conspicuous photochromic behaviors were synthesized. The various photochromic and MFC behaviors of these compounds could be regulated by the fluorinated loop's sizes. Remarkably, solid powder of the fluorinated mesocyclic TPE, 441F , showed intuitional color change, switching from white to a visually recognizable crimson after UV irradiation, and then it reversed to its original color within 42 s. [Display omitted] • A series of novel fluorinated mesocyclic TPE compounds with conspicuous photochromic behaviors were synthesized. • The photochromic and MFC behaviors of these mesocyclic compounds could be regulated by the fluorinated loop's sizes. • 441F powder switched from white to intuitional crimson color after UV irradiation, then reversed to white within 42 s. • Comparing the previous photocyclization in TPE, this is the first example of photocyclization on benzene ring of TPE. [ABSTRACT FROM AUTHOR]