PET Fluorescent Boronic Acid Chemosensors

The normal arylboronic acid fluorescence sensors are based on the a-PET mechanism, that is, with the fluorophore as the eleetron acceptor of the PET process. As a result, the fluorescence of the boronie aeid sensors is strong in a solution at acidic pH, which is actually detrimental to the recognition of analytes at acidic pH, because the fluoreseenee enhancement will be diminished by the strong background fluorescence.  

The d-PET effeet has been proposed for these carbazole-based bis-boronie aeid sensors, where d-PET indieates that the fluorophore is the eleetron donor at the photoexeited state, with the protonated N-atom and the binding site as the eleetron aceeptor. Henee, in the acidic pH region, with the protonated N-atom, eleetron transfer from the carbazole fluorophore to the protonated amine and the boronie aeid moiety occurs. As a result, the fluorescence is actually quenched at aeidie pH, which is in stark contrast to the fluorescence-pH relationship of normal a-PET fluorescence sensors. With the diminished background fluorescence of the chiral bis-boronic acid 

6 Boronic Acid-Chiral Amine Assemblies for NMR Determination of the e.e. Values of Chiral Diols 

James and Bull et al. developed a molecular assembly of boronic acids for 

For example, they reported a simple three-eomponent chiral derivatization 

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