含稠合外环的氟硼荧染料类pH荧光探针的研究

Study on pH Fluorescent Probe Based on Exocyclic Ring-Fused Boron Dipyrromethene Fluorophore

以环己醇为起始原料,首先经过改进的三步法制备出2-乙氧羰基-3,4-四亚甲基吡咯,并用过量氢化铝锂高温还原得到2-甲基-3,4-四亚甲基吡咯;再将其分别与4-二甲氨基苯甲醛、4-羟基苯甲醛、4-甲氧基苯甲醛、苯甲醛、4-醛基苯并冠-5等芳醛衍生物在三氟乙酸的催化作用下发生缩合反应,用2,3-二氯-5,6-二氰基-1,4-苯醌(DDQ)氧化并依次用N(Et)3和BF3.OEt2处理后得到5种新型含稠合外环的BODIPY类染料衍生物。研究了它们的吸收和发射光谱,并采用荧光光谱滴定方法研究了它们在CH3OH-H2O(1∶1,V/V)中对pH的响应能力。结果表明:BODIPY 1和2在可见光激发下,可以分别作为酸、碱环境下的pH荧光探针并且这两种荧光探针在荧光"开/关"状态之间的转化可以通过质子化和去质子化的方式调控。另外,还初步探讨了荧光探针的设计原理及传感机制。

2-Ethoxycarbonyl-3,4-tetramethylenepyrrole was prepared by the improved three-step synthetic route using cyclohexanol as starting material. After treating with excess LiA1H4 at high temperature, 2-methyl-3,4- tetramethylenepyrrole prepared in situ was reacted with various kinds of arylaldehyde derivatives including 4- dimethylaminobenzaldehyde, 4-hydroxybenzaldehyde, 4-methoxybenzaldehyde, benzaldehyde and 4-formyl benzo crown-5, respectively, in the presence of CF3 COOH as catalyst and oxidized with DDQ, followed by treating with N（Et）3 and BF3~ Et20 to provide five kinds of novel BODIPY dye derivatives fused with exocyclic rings. The absorption and steady-state fluorescence properties of as-synthesized dyes were investigated. The speetrofluorometrie titrations were performed to examine their responsive abilities to pH in CH30H-H20 （1： 1, V/V）. The results indicated that BODIPY 1 and 2 can be applied as a fluorescent probe for pH sensing in the acid and alkaline region, respectively, under exciting with visible light, and the fluorescence ＂ON/OFF＂ states in BODIPY 1 and BODIPY 2 can be modulated by protonation/deprotonation process. Moreover, the design principle and sensing mechanism of two probes were also preliminarily discussed.