香豆素基甲醛荧光探针的合成及其性能研究

Study on Synthesis and Properties of Coumarin-Based Fluorescence Probe for Formaldehyde

以4-甲基-7-羟基香豆素(MC)为原料,采用Duff反应对其进行甲酰化,合成中间体4-甲基-7-羟基-8-甲酰基香豆素(MFC),MFC再与水合肼缩合,合成了一种检测甲醛的荧光探针4-甲基-7-羟基-8-甲腙香豆素(CNH)。产物经红外(IR)光谱、~1H NMR、质谱(MS)等方法进行结构表征.采用荧光光谱对其性能进行了研究,结果显示:在25℃,pH=7.4,λ_(ex)/λ_(em)=325/450 nm的条件下,CNH与甲醛的反应约400 s即可完成,对甲醛表现出非常高的灵敏度,检测限为1.0×10^(-5) mol/L。选择H_2O_2、CuSO_4、CaCl_2、甲醛、苯甲醛、甘氨酸和丙酮等进行对比实验,发现CNH只与甲醛作用后荧光有很大的增强,表现出非常高的选择性,并且在紫外灯照射下用肉眼就可以观察到随着甲醛的加入,其颜色将发生显著的变化,可进行实时目视比色法检测。其作用机理可能是由于探针CNH的-NH_2的给电子作用,由于光诱导电子转移(PET),荧光猝灭,与甲醛作用后生成-N=CH_2而PET受阻,荧光恢复。该甲醛荧光探针兼具比色和荧光增强双重特点,预期在活体细胞检测方面有良好的应用前景。

The intermediate 4-methyl-7-hydroxy-8-formylcoumarin(MFC)was synthesized from 4-methyl-7-hydroxycoumarin(MC)by Duff reaction for the first time.Then a fluorescence probe(4-methyl-7-hydroxy-8-hydrazonecoumarin(CNH)was synthesized by condensation of MFC with hydrazine hydrate.The products were characterized by IR,1H NMR and MS.A series of properties experiments were carried out by fluorescence spectra.The results indicated that the reaction between CNH and formaldehyde(FA)would finish about 400 s(25℃,pH=7.4,λex=325 nm,λem=450 nm),and the detection limit of FA was 1.0×10-5 mol/L.The comparative experiments were carried out by H2O2,CuSO4,CaCl2,CH3CHO,C6H5CHO,glycine and acetone,and it was found that the fluorescence of CNH was enhanced greatly when it was treated only with FA.In addition,with the addition of FA,its color changed dramatically,which was helpful to real-time qualitative visual colorimetric detection.CNH displayed little fluorescence because of a photoinduced electron transfer(PET)pathway from hydrazine to the dye.However,in the present of FA,the PET pathway was suppressed and fluorescence recovered.A turn-on signal could be detected.The probe CNH has the advantages of both colorimetric and fluorescence enhancement and shows great potential in detecting or imaging in living cells,and this molecular design provides new insights into the development of new probes for FA.