Synthesis And Mechanofluorochromic Properties Of Fluorescent Dye Molecules Containing DSA And TPA

Mechanofluorochromic is a phenomenon in which the optical properties and color of a substance change when stimulated by an external force.Organic fluorescent dyes with mechanofluorochromic properties have potential applications in pressure sensors,optical storage,memory chips,and safety inks,which have attracted widespread attention.However,most traditional organic luminescent molecules have largeπ-conjugated structures,which makes them susceptible to aggregation-induced quenching（ACQ）effect.This effect will affect the mechanofluorochromic activity of the material to some extent.Researchers have designed and synthesized numerous organic dye molecules to overcome the ACQ effect.Among them,aggregation-induced emission（AIE）molecules are an important class of anti-ACQ molecules that exhibit excellent photophysical properties in the aggregated state and can be a significant source of mechanochromic materials.In this paper,we designed and synthesized two types of fluorescent dye molecules using typical AIE molecules,9,10-distyrylanthracene and triphenylamine as parent nuclei,and investigated their mechanochromic properties,respectively.The specific work content is as follows:1.Synthesis of 9,10-distyrylanthracene（DSA）derivative molecules and investigation of their mechanofluorochromic properties.Using 9,10-di（chloromethyl）anthracen as the initial raw material,an intermediate was synthesized by Arbuzov reaction,Wittig Horner,and Sonogashira reactions.Then,the final products,namely D₁-OCH₃,D₂-C（CH₃）₃,D₃-CF₃,and D₄-F,were synthesized by Knoevenagel condensation reaction with 4-methoxybenzyl cyanide,4-tert-butylphenyl-acetonitrile,4-（trifluoromethyl）phenylacetonitrile,and 4-fluorobenzyl cyanide.Under solid-state grinding,all four compounds exhibited typical mechanofluorochromic properties,with the fluorescence emission peak redshifted by16 nm,19 nm,9 nm,and 16 nm,respectively.Further treatment through solvent vapor and heating resulted in a blue shift in the fluorescence emission peak of the ground samples to some extent.This paper explores the underlying mechanism of the mechanofluorochromic properties of the four compounds,revealing through XRD analysis that the reversible mechanofluorochromic transformation process in the compounds occurred between a"microcrystalline-amorphous"state.2.Synthesis of triphenylamine（TPA）derivative molecules and investigation of their mechanofluorochromic properties.Using 4-bromotriphenylamine as the initial raw material,an intermediate was synthesized through the Vilsmeier-Haack reaction,Knoevenagel condensation reactions,the final products,namely T₁,T₂ and T₃,were synthesized by Knoevenagel condensation reaction with iminodibenzyl,diphenylamine and carbazole respectively.The mechanofluorochromic properties of the three compounds were studied,with T₁exhibiting excellent mechanofluorochromic activity.Further treatment through heating resulted in a blue shift in the fluorescence emission peak of the ground samples.Moreover,the reversible mechanofluorochromic transformation process of compound T₁ exhibited good repeatability and sensitivity to pressure stimulation response.Therefore,we coated compound T₁ on filter paper to prepare reversible writing materials that can be used for"writing-thermal erasure"reversible cyclic operations.We hope that such research can be used in the future to develop recyclable writing media,reducing paper consumption and waste.