Non-Boronic Acid Appended Synthetic Sensors for Saccharides

3 Non-Boronic Acid Appended Synthetic Sensors for Saccharides 

A great amount of attention is currently devoted to the development of synthetic molecular receptors with the ability to recognise saccharides. This book is primarily concerned with the role of boronic acids in that recognition process, although many systems have been developed which use non-covalent interactions for recognition. A few examples are given below to provide a brief illustration of research in this area. (For a more comprehensive insight, the reader is directed to two recently published reviews. ) 

The first synthetic saccharide receptor 9 was documented in 1988 by Aoyama et The calixarene framework is not large enough to actually permit the encapsulation of a saccharide within the central annulus of the bowl, but it does permit face-to-face recognition to occur between the calixarene s upper rim hydroxyls and those of the saccharide. Flowever, in order to complex saccharides in water Aoyama needed to use very high concentrations of saccharides (100 mM- M). 

Das and Hamilton have employed phosphonate moieties in sensors such as the rigid chiral spirobifluorene 13. The racemate was used directly and although the exact nature of the hydrogen-bonding motif could not be determined excellent binding was observed with octylglucosides in organic solvents. 

The enantioselectivity was also determined and reported as 5.1 1, the greatest value reported for saccharide enantioselective discrimination by non-covalent interactions. The binding constant (Kf) for sensor 13 with octyl-p-o-glucopy-ranoside 11 was 47,000 M in deuterated acetonitrile. 

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