Based On 2-aminopyrimidine Unit To Construction And Properties Of Stimuli-responsive Organic Fluorescent Materials

Stimuli-responsive materials are a class of intelligent materials with broad potential application,and have attracted wide attention in recent years.The color and fluorescence of them could be modulated by the stimulation with external factors（such as temperature,mechanical stress,p H value,ions,light,etc.）,making them widely used in data storage,information anti-counterfeiting,chemical sensors,cell imaging,and other fields.2-Aminopyrimidine has good coplanarity and high electron affinity,which gives it an appropriate building block in the construction of chromophores for optical sensors and p H-responsive materials.In this work,five new molecules based on 2-aminopyrimidine were designed and synthesized,their properties including stimulus responses,security ink,and cell fluorescence imaging were systematically study.The specific research contents are as follows:1.BMS-PA and BHP-PA were synthesized by using 2-aminopyrimidine,benzene,and pyrene units.The substituent effects,solvation effects,and acidichromism of them were systematically investigated.All of them not only exhibited significant protonated in solution,but also displayed excellent acidichromism in solid states.Upon triggering with TFA,the color of BMS-PA immediately changed from the colorless solution to the yellow solution,and the bright blue emission changed to bright green,while the color of the BHP-PA compound changed to dark yellow,and the strong cyan fluorescence changed to bright yellow.Similarly,the yellow of BMS-PA powder turned to black under TFA fumigation and the fluorescent was also gradually quenched during these processes.It should be noted that all their color of them could be completely restored by stimulating with TEA.Furthermore,metal ion selection experiments of BMS-PA and BHP-PA were performed,indicating all of them could be served as Cr³⁺,Al³⁺and Fe³⁺sensors and realized rapid detection of Cr³⁺,Al³⁺and Fe³⁺.Finally,the application of BMS-PA and BHP-PA in security ink was discussed.2.By introducing the 9-phenyl carbazole unit into the 2-aminopyrimidine unit by Knoevenagel condensation reaction,a multiple stimulation response properties BPCT-PA molecular was synthesized,and the effects of solvent polarity,protonation,and metal ion on its properties were systematically studied.The results show that BPCT-PA showed significant reversible acid chromic properties.Under the action of TFA,the initial yellow solution immediately becomes a carmine solution,and the green fluorescence becomes bright red after acid stimulation.Under solid conditions,the orange powder gradually turns black with the duration of TFA,and the fluorescent color gradually darkened from orange and is finally quenched,which makes it have safe ink characteristics.Metal ion selectivity experiments showed that BPCT-PA recognizes Cr³⁺,Al³⁺and Fe³⁺,which proved that the compound can serve as a good metal ion test paper and achieve rapid detection of Cr³⁺,Al³⁺and Fe³⁺.Moreover,the compound showed low cytotoxicity and good biocompatibility,and we successfully applied it to cell fluorescence imaging.3.The triphenylamine and anthracene unit were introduced into the2-aminopyrimidine unit by Knoevenagel condensation reaction to synthesize BTPAT-PA and BAT-PA,and the effects of solvation effect,protonation effect,and reactive oxygen species and metal ions on their properties were systematically studied.The results show that both BTPAT-PA and BAT-PA show significant reversible acidatochromic properties,and after protonation,the colors of BTPAT-PA and BAT-PA are immediately changed from the initial bright yellow and yellow solution to purplish red and dark yellow solutions,and the bright green fluorescence rapidly changes to orange-red.Similarly,the solid powder can also be protonated,and its color gradually changes black with the protonation time,and the fluorescence is quenched.Reactive oxygen species selectivity experiments showed that BTPAT-PA and BAT-PA could recognize·OH well,and we successfully achieved rapid detection of·OH by preparing rapid detection bands.Notably,BTPAT-PA was able to specifically recognize Hcy,indicating that this compound serves as a bifunctional fluorescent molecular probe for both·OH and Hcy.Moreover,ion selection experiments with BTPAT-PA and BAT-PA demonstrated that both showed good recognition of Cr³⁺,Al³⁺and Fe³⁺and were able to prepare test strips for rapid detection of Cr³⁺,Al³⁺and Fe³⁺.Cytotoxicity tests demonstrated lower toxicity of BTPAT-PA and BAT-PA and can be used for fluorescence imaging of HeLa cells.