Ferrocene carbohydrate binding

A. N. J. Moore, D. D. M. Wayner, Redox switching of carbohydrate binding to ferrocene boronic acid, Canadian Journal of Chemistry - Revue Canadi-enne De Chimie 1999, 77, 681. 

Chiral ferroceneboronic acid derivatives have been synthesized by Ori and tested for chiral electrochemical detection of monosaccharides. The best discrimination was observed for L-sorbitol and L-iditol at pH 7.0 in 0.1 mol dm phosphate buffer solution. Moore and Wayner have explored the redox switching of carbohydrate binding with commercial ferrocene boronic acid. From their detailed investigations, they have determined that binding constants of saccharides with the ferrocenium form are about 2 orders of magnitude greater than those for the ferrocene form. The increased stability is ascribed to the lower pKe of the ferrocenium (5.8) than ferrocene (10.8) boronic acid. 

Credi, Raymo and coworkers reported in 2002, the preparation of a new type of carbohydrate-coated, dendronized ferrocenes [46], The structures of these den-drimers are illustrated by compounds 14 and 15. Binding interactions with p-CD were investigated by liquid secondary ion mass spectrometry, 11 NMR spectroscopy, voltammetry and circular dichroism. Upon addition of P-CD, cyclic voltammetric experiments showed data similar to those obtained with our dendronized ferrocenes, that is, a CD-induced current level decrease and anodic half-wave potential shift. At 22°C, these authors obtained K values of 2,000 200 and 1,300 200 M-1 for the complexation of 14 and 15, respectively, by p-CD in 0.1MNaClO4. Similar dendrimers in which carbohydrate branches are covalently attached to both cyclopentadienyl rings of the ferrocene residue were not bound at all by P-CD, reflecting the shielding of the core ferrocene center in these more symmetric compounds. 

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