초록
<P>Fluorescence recognition of <SMALL>D</SMALL>-glucose in water with excellent sensitivity, selectivity, and chiral selectivity is desired because <SMALL>D</SMALL>-glucose is an essential component in biological and pathological processes. We report an innovative approach that exploits the 1:2 stoichiometric inclusion complexes of γ-cyclodextrin (γ-CyD) with two molecules of fluorescent monoboronic acid-based receptors, which form a <I>pseudo</I>-diboronic acid moiety as the recognition site for <SMALL>D</SMALL>-glucose in water. Two monoboronic acids (<B>1F</B> and <B>2N</B>) were easily synthesized without heating or column purification. The 1:2 stoichiometric inclusion complexes (<B>1F/γ-CyD</B> and <B>2N/γ-CyD</B>) were prepared in a mixture of dimethyl sulfoxide/water (2/98 in v/v) by mixing γ-CyD and the corresponding monoboronic acids. Both <B>1F/γ-CyD</B> and <B>2N/γ-CyD</B> exhibited strong turn-on response to <SMALL>D</SMALL>-glucose with excellent selectivity over nine other saccharides in the water-rich solvent at pH 7.4 owing to the ditopic recognition of <SMALL>D</SMALL>-glucose by the <I>pseudo</I>-diboronic acid moieties. The limits of detection of <B>1F/γ-CyD</B> and <B>2N/γ-CyD</B> for <SMALL>D</SMALL>-glucose were 1.1 and 1.8 μM, respectively, indicating the remarkable sensitivity for the detection of <SMALL>D</SMALL>-glucose at μM levels. <B>1F/γ-CyD</B> and <B>2N/γ-CyD</B> also demonstrated chiral-selective recognition of <SMALL>D</SMALL>-glucose, which is apparent from the 2.0- and 6.3-fold enhancement of fluorescence by the addition of <SMALL>D</SMALL>-glucose relative to <SMALL>L</SMALL>-glucose addition, owing to the chiral <I>pseudo</I>-diboronic acid moieties produced by the chiral γ-CyD cavity. To the best of our knowledge, <B>2N/γ-CyD</B> has the highest <SMALL>D</SMALL>/<SMALL>L</SMALL> selectivity among hitherto reported fluorescent diboronic acid-based receptors.</P><BR>[FIG OMISSION]</BR>