Synthesis And Characteristics Of Novel Piezofluorochromic Materials Based On 9,10-divinylanthracene

Since the finding of aggregation-induced emission phenomena by Benzhong Tang,the AIE materials already attract intensive attention due to the wide applications in many fields such as detection,biological imaging,sensor edc.In the last decade,numerous AIE materials have been designed and synthesized,some of them exhibited obvious piezofluorochromic（PFC）properties.In which,9,10-bisvinylanthracene derivatives have become the research hotspots of organic piezofluorochromic materials because of their excellent AIE and sensitive PFC properties since they were found in2010.Herein,a series of conjugated 9,10-bisvinylanthracene derivatives and non-conjugated anthracene derivatives were designed and synthesized.Their AIE effect and piezofluorochromism were examined,and their structure-property relationships were intensively investigated.The main contents and achievements are as follows:（1）To further investigate the effect of the alkoxy-chain length on the PFC and optical propertis of conjugated 9,10-bisvinylanthracene derivatives,four derivatives of that（BNAs）were designed and successfully synthesized.We found they not noly exhibited the AIE effect,but also had the nature that their PFC properties showed gradually decrease with the length increase of the alkoxy chain.The mechanism showed that the introduction of the alkoxyl chain and the increase of the chain length can weaken the distortion degree of molecular conformation,decrease the crystal layer spacing,increase the intermolecular interaction and make the molecular packing mode tend to be close.Therefore,the molecular packing mode of BNA crystal was the most loose,which meant it was easy to occur crystalline-amorphous transformation and BNA had the best PFC performance(Δλ_PFC was 26 nm).But BNA-12 was not sensitive to external pressure and had the worst PFC property(Δλ_PFC was only 11 nm).This phenomenon was due to the small change of tight packing mode and molecular conjugation degree under pressure.Thus,the change of the molecular packing mode was an important reason for PFC property.（2）To further investigate the effect of the alkoxy-chain length on the PFC and optical propertis of non-conjugated anthracene Schiff base derivatives,three compouds（DNCAs）were designed and successfully synthesized.We found all of them showed aggregation-induced emission decrease,and there is no specific law between the length of alkoxy chain and the discoloration property of DNCAs.Among them,DNCA-4 and DNCA-12 had obvious PFC properties,and theirΔλ₁ respectively were 26 nm and 37nm.In addition,only DNCA-12 could display solvatochromic property after dichloromethane fuming and theΔλ₃ was 37 nm.The mechanism showed that the micro-crystalline of DNCA-4 and DNCA-12 can be destroyed or have polymorphic transformation after grinding,which makes them have PFC performance.Furthermore,the solvatochromic property of DNCA-12 was also due to the transformation of molecular packing mode from crystalline to amorphous state in the presence of dichloromethane fumigation.Thus,the discoloration mechanism of DNCAs had a relationship with the change of the molecular stacking pattern.