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.