Controllable CPL response driven by achiral UV-photosensitive dichroic dye through cholesteric liquid crystals

Versatile stimuli-responsive circularly polarized luminescent(CPL)materials have potential applications in information storage,security encryption,and intelligent displays.In this study,the Z/E isomerization of ultraviolet(UV)-photosensitive achiralα-cyanostilbene derivative was used as an achiral dichroic dye(Switch)to drive the controllable CPL-active response in cholesteric liquid crystals(CLCs).Under irradiation by 365 nm UV light,the resulting CLCs-Z-Switch underwent a Z-to-E configuration isomerization as CLCs-E-Switch,accompanied by a decrease in its dichroic order parameter(SFvalue)from 0.15to 0.07.Although the quantum yield(QY)of CLCs-E-Switch increased from 8.1%(CLCs-Z-Switch)to 16.8%,the corresponding glumvalues of CPL emission decreased from+0.55/-0.57 to+0.37/-0.39 due to a decrease in the order of helical arrangement of E-Switch in E7 media.This study enables photosensitive CLCs-Switch to be applied for optical information storage devices.

Trace Ir(Ⅲ)complex enhanced electrochemiluminescence of AIE-active Pdots in aqueous media

Trace Ir(Ⅲ)complex enhanced aggregation-induced electrochemiluminescence(AIECL)of poly-tetraphenylethene(p TPE)in aqueous media was investigated for the first time.The poly-TPE end-capped by Ir(Ⅲ)complex(Ir@p TPE)and its corresponding model polymer poly-TPE(Ph@pTPE)could be synthesized by Suzuki coupling polymerization reaction of 1,2-bis(4-bromophenyl)-1,2-diphenylethene(M-1)with 1,2-diphenyl-1,2-bis(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethene(M-2)and the continuous Suzuki coupling end-capped reaction of poly-TPE-pinacol boronate with(pq)2 Ir(pico)Br and bromobenzene,respectively.Subsequently,the corresponding Ir@p TPE Pdots and Ph@p TPE Pdots encapsulated with poly(styrene-co-maleicanhydride)(PSMA)could be obtained by nanoprecipitation method.Compared with Ph@p TPE Pdots,the Ir@p TPE Pdots with a trace amount of Ir(Ⅲ)complex(1.34‰of Ir(Ⅲ)content,wt)could exhibit 9.9-fold enhancement of the electrochemiluminescence(ECL)signal for visual emission.This work provided a novel strategy on designing highly efficient ECL materials based on trace Ir(Ⅲ)-end capping AIE-active polymer dots.