Ferrocene–Carbohydrate Conjugates as Electrochemical Probes for Molecular Recognition Studies

We report two methods that have allowed the attachment of glucose, mannose and lactose to one or both of the cyclopentadienyl rings of ferrocene. The resulting ferrocene–carbohydrate conjugates were synthesised by the reaction of thioglycosides with ferrocenemethanol and 1,1′‐ferrocenedimethanol in acidic media. A second method based on the regiospecific copper(I)‐catalysed cycloaddition of propargyl glycoside, azidomethyl and bis(azidomethyl)ferrocene as well as azidoethyl glycoside and ethynylferrocene was also used and led to the synthesis of 1,2,3‐triazole‐containing glycoconjugates. The electrochemical behaviour of the synthesised glycoconjugates was investigated. In addition, their binding interactions with β‐cyclodextrin were studied by means of NMR spectroscopy, isothermal titration calorimetry, and cyclic and differential pulse voltammetric experiments. These techniques allowed the determination of the thermodynamic parameters of the complexes, the stability constants for the complexes formed with both the neutral and the oxidised states of the ferrocenyl glycoconjugates, the mode of inclusion and the diffusion coefficients for both the glycoconjugates and the complexes. Glycoferrocenes as sensors: Ferrocene–carbohydrate conjugates with different tethers and sugars were synthesised by two convenient methods. The electrochemical behaviour of these compounds was investigated, as well as their complex formation with β‐cyclodextrin (see figure) by NMR, ITC, CV and DPV experiments.