Mechanofluorochromic Properties Of Triphenylamine And Tetraphenylethylene Derivatives

Due to the special optical properties,mechanofluorochromic materials are widely used in storage equipment,security printing,data storage equipment,optical display,etc.Its fluorescence color can be reversibly switched between different colors after being stimulated by external forces,such as mechanical force,pressure,friction and so on.The length of the alkyl chain,the D-π-A structure of the molecule,the distortion of the molecule,the isomer effect have a great influence on the fluorescence discoloration of the molecule.The different positions of the receptor substituents are accompanied by changes in the properties of the compounds themselves.Salicylaldehyde schiff base compounds are easy to be modified and synthesized.The modified salicylaldehyde schiff base is multifunctional and widely used.Therefore,multifunctional force-induced fluorescent discoloration materials have become a research hotspot in recent years.In this paper,seven derivatives of triphenylamine（TPA）and tetraphenylethylene（TPE）with the structure of the receptor were designed and synthesized.Their photophysical properties were studied.Meanwhile,the effects of isomers on the mechanofluorochromic properties were investigated.The selectivity of fluorescent probe molecule TPEMO for ion and anion recognition was investigated.The specific contents are as follows:Chapter 1:The development status and influencing factors of mechanofluorochromic materials are summarized,and the ion recognition performance of salicylaldehyde schiff base compounds is briefly summarized.Finally,the main research content and significance of this paper are described.Chapter 2:Design and synthesis of three non-planar isomers（TPA-o,TPA-m and TPA-p）with D-π-A structure based on triphenylamine.These three derivatives of triphenylamine based on D-π-A structure produce structure-dependent fluorescence discoloration.The position of the receptor substituents has a great influence on the conformation and packing pattern of the molecules and mechanofluorochromic properties.Studies of single crystal structure,powder X-ray diffraction（PXRD）and differential scanning calorimetry（DSC）indicate that the fluorescence discoloration caused by molecular forces is caused by the phase transition from crystal state to amorphous state.Chapter 3:Design and synthesis of three non-planar isomers（o-TPEC,m-TPEC and p-TPEC）with D-π-A structure based on tetrastyrene.All of the three molecules exhibit aggregation induced luminescence and mechanofluorochromic properties.Studies of single crystal structure,powder X-ray diffraction（PXRD）and differential scanning calorimetry（DSC）indicate that the fluorescence discoloration caused by molecular forces is caused by the phase transition from crystal state to amorphous state.Chapter 4:A tetrastyrene functionalized salicylaldehyde schiff base TPEMO was designed and synthesized.This molecule not only exhibits aggregation induced emission（AIE）and reversible mechanofluorochromic properties,but also can be used as a fluorescence chemical sensor to selectively identify Zn²⁺and CO₃^2-.