Design,Synthesis,Properties,and Application Of A Multi-Stimuli Responsive Smart Materials Based On Bistriaromatic Ene N-Aryl Fluorenylidene-Acridane

In our fisrt subject,N-phenyl fluorenylidene-acridane?Ph-FA?compounds with electron--withdrawing and-donating substituents?H,MeO,Ph,NO₂,Br,F?at the para position of the phenyl group were successfully synthesized by the Barton-Kellogg reaction of N-aryl thioacridones and diazofluorene.By using the substituent on nitrogen to alter electronic properties,both the folded and twisted conformers of p-NO₂-C₆H₄-FA were crystallographically characterized to understand charge transfer from the electron-donating acridane moiety to the electron-accepting fluorenylidene moiety.Ground state mechanochromism,thermochromism,vapochromism,and proton-induced chromism were demonstrated by utilizing folded/twisted conformational change between the conformers.Protonation and chemical oxidation of Ph-FA gave two stable acridiniums,namely,fluorenyl acridinium and acridinium radical cation.The present study will contribute to the development of functional dyes and organic semiconductorsTo directly control the electronic structures of the folded and twisted conformers,six functional groups,namely,methyl,methoxyl,fluoro,bromo,thienyl,nitro substituents,which range from electron-donating to electron-withdrawing in terms of inductive or conjugation effects,were successfully introduced functional grouips onto the fluorene moiety of the N-phenyl-substituted fluorenylidene-acridane?Ph-FA?system in our second subject This enabled equilibrium and thermodynamic studies to determine an equilibrium constant and changes in enthalpy,entropy,and free energy in solution,providing an in-depth understanding of the equilibrium behavior of functional overcrowded alkenes.Single-crystal X-ray diffraction analysis of the folded and twisted conformers and of unexpectedly-obtained crystals containing both conformers were performed to investigate charge transfer from the acridane to the fluorene moiety.Various chromic behaviors such as mechanochromism,thermochromism,solvatochromism,vapochromism,and proton-induced chromism were shown to provide information on conformational isomerism in this systemChromism,which has been studied for a long time,is generally caused irreversibly by some stimulations such as mechanical force,thermal,photo,accompanying with morphological transformation.To push forward this research field,chromism realized with conformational conversion was proposed and successfully proved in our third work.To find a good chromism molecule candidate based on this proposal,a proper equilibrium between two isomers is required.To meet this requirement,Ph-fluorenylidene-acridane?Ph-FA?was modified to obtain four kinds of FAs derivatives,whose functional groups range from electron-donating to electron-withdrawing inductive/conjugation effects.With these structures,various intuitive chromic behaviors,such as mechanical-,thermal-,solvato-,vapor-,and proton-induced chromism were shown.Rather than morphological variation,they result from conformational isomerization,which probabilize a reversible chromism process.Besides,these structure also demonstrate excellent piezofluorochromism.There are many literatures regarding equilibrium of isomers,where equilibrium is not discussed in-depth.In this work,based on variable temperature UV-Vis,a whole new approach is poineered to carry out thermodynamic study.SCLC measurement shows that the twisted conformers are of ambipolar?hole/electron?transport properties.With this,the proposal that FAs work as a dopant of perovskite active layer to increase charge mobility of PSCs was examined.Charge transfer in the twisted conformers were also examined with stabilization by polar solvents.