Synthesis And Optical Switching Properties Of Chiral Luminescent Diarylethylene

Materials with optical switching properties are widely used in highdensity optical data storage,logic gates,biological imaging,and optoelectronic devices due to their smart response to light stimuli.Nevertheless,by using chiral optical signals(such as optical rotation dispersion(ORD),circular dichroism(CD)and circularly polarized luminescence(CPL))as optical switches,it will provide much more research dimensions in the fields of chiral sensing,optical display,information storage and asymmetric catalysis.Conventional chiral photoswitchable fluorescent molecules were designed by integrating fluorescent chromophores with photochromic units on the same molecule,while chiral moieties were connected through covalent linkage or various types of non-covalent interactions.Nevertheless,only fluorescent turnoff type molecules designed based on this strategy can be reversibly switched.This kind of“Turn-off” mode diarylethylene materials have low sensitivity and poor fluorescence stability,which greatly limits its application in various aspects.In this paper,we designed and synthesized a class of chiral emissive diarylethylene derivatives with high fluorescence quantum yields in the "Turn-on" mode by using diarylethylene as the parent moiety,endowed with fluorescence-emitting properties through sulfonation of thiophene sites.Chiroptical property was achieved by connecting to a bis(dinaphthyl)-type chiral moiety.The details contain the following parts:Firstly,the types and applications of switchable luminescent dyes and the mechanisms to achieve the switchable properties are reviewed,and the current development of chiral luminescent materials is summarized.Subsequently,a chiral luminescent diarylethylene was prepared by modifying the parent unit of diarylethylene,and a series of photophysical properties were thoroughly tested.The experimental results show that the two isomers of this molecule have distinctly different properties of UVvisible absorption,fluorescence emission,CD,CPL,single photon absorption based upconversion luminescence(SPA-UCL),and triplettriplet annihilation based upconversion luminescence(TTA-UCL),all of which have the potential to become optical switching channels.Finally,the photoswitching properties of CD,luminescence,upconversion luminescence and other photophysical properties were further investigated.The results show that the six photoswitchable channels are well reversible and fatigue-resistant after repeated experiments with multiple open and closed loops.