Molecular recognition of a self-assembled monolayer of a polydithiocarbamate derivative of #beta#-cyclodextrin on silver

摘要

The synthesis and molecular recognition properties of a new sulfur containing #beta#-cyclodextrin (#beta#-CD) derivative chemisorbed on a silver surface are described. Hepta-6-amino-6-deoxy-#beta#-CD was allowed to react with CS_2 in the presence of ammonia to give a mixture of partially substituted dithiocarbamate derivatives with an average degree of substitution of 4.5. A modified silver electrode with this derivative is capable of discriminating between the three positional isomers of nitrobenzoate ion and nitrophenol, as determined by cyclic voltammetry. Only the meta- and para-isomers give a signal corresponding to the reduction of the nitro group. This is attributed to the different orientations of the nitro group with respect to the silver surface after inclusion in the CD cavity. Experiments in the presence of cyclohexanol showed a decrease in signal intensity of the meta- and para-isomers which is associated with the competitive complexation of this guest, suggesting that the electroactive probe is complexed to the cavity.