State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China.
J Fluoresc. 2011 Sep;21(5):1979-86. doi: 10.1007/s10895-011-0898-z. Epub 2011 May 19.
Chiral bisboronic acid chemosensors based on ethynylated carbazole were prepared. The chiral chemosensors show red-shifted emission than the chemosensors with unsubstituted carbazole fluorophore. a-PET effect was found for the chemosensors, which is different from our previous observation of the d-PET effect for boronic acid chemosensors based on carbazole. Enantioselective recognition of tartaric acids was implicated with these chemosensors. Consecutive fluorescence emission enhancement/diminishment were observed with increasing the concentration of the tartaric acids, which is tentatively assigned to the transition of the binding stoichiometry from 1:1 binding to 1:2 binding. In particularly interesting is the improved fluorescence response at acidic pH for recognition of tartaric acids, which is rarely observed for a-PET chemosensors. We propose that the sensing is due to hybrid mechanism of a-PET/d-PET and conformational restriction upon binding. Our results will be useful for design of chiral boronic acid chemosensors with improved fluorescence response at acidic pH, which are rarely reported.
基于炔基咔唑的手性双硼酸化学传感器被制备。相较于不含取代基咔唑荧光团的化学传感器，手性化学传感器显示出红移发射。我们发现了化学传感器的 a-PET 效应，这与我们之前对基于咔唑的硼酸化学传感器的 d-PET 效应的观察不同。这些化学传感器可以对酒石酸进行对映选择性识别。随着酒石酸浓度的增加，观察到连续的荧光发射增强/减弱，这被初步归因于结合计量比从 1:1 结合到 1:2 结合的转变。特别有趣的是，在酸性 pH 值下识别酒石酸时，荧光响应得到了改善，这在 a-PET 化学传感器中很少见。我们提出这种传感是由于 a-PET/d-PET 的混合机制和结合时的构象限制。我们的结果将有助于设计在酸性 pH 值下具有改善荧光响应的手性硼酸化学传感器，这在文献中很少报道。
