含稠合外环的氟硼荧染料类pH荧光探针的研究

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。

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

2-Ethoxycarbonyl-3,4-tetramethylenepyrrole was prepared by the improved three-step synthetic route using cyclohexanol as starting material.After treating with excess LiAlH4 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 CF3COOH as catalyst and oxidized with DDQ,followed by treating with N(Et)3 and BF3·Et2O 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 spectrofluorometric titrations were performed to examine their responsive abilities to pH in CH3OH-H2O(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.