Considerable fluorescence enhancement upon supramolecular complex formation between berberine and p-sulfonated calixarenes

Remarkably strong binding of berberine, a clinically important isoquinoline alkaloid, to 4-sulfonatocalix[8]arene leads to considerable fluorescence quantum yield increase at pH 2, which may be utilized in the development of a fluorescent probe. The effects of pH and the cavity size of sulfonatocalixarenes on the stability and fluorescent properties of the complexes are revealed.