Voltammetric investigation of new boronic ester-substituted triphenylamines-based redox receptors in solution and attached to an electrode surface. Effects of F~- as an anionic guest

摘要

Triphenylamines mono-, di- and trisubstituted by boronic ester unit(s) were designed as powerful redox-active receptors for Lewis hard bases like fluoride anion. Their voltammetric behaviour was found to be dramatically changed upon the addition of this halide. Depending on the degree of substitution of triphenylamines, the binding of F~- to the boron atom led to the appearance of one to three new redox system(s). The binding constants determined for their neutral form ranged from 1.0 X 10~2 to 4.0 X 10~2 and were dramatically enhanced upon their oxidation into radical cation (3.0 X 10~5 - 1.6 X 10~7). The fixation of such electroative compounds to the electrode surface has been achieved from the anodic oxidation of a vinyl-substituted bipodal receptor. The polymer films showed a reversible and stable response in a dried organic medium. Unfortunately, the voltammetric changes indicative of a complexation phenomenon were not observed in the presence F~- and only a degradation of the film electroactivity was noticed.