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

Triphenylamines mono-, di- and trisubstituted by boronic ester unit(s) were designed as powerful redox-active receptors for Lewis hard bases like fluo ride anion. Their voltammetric behaviour was found to be dramatically chang ed upon the addition of this halide. Depending on the degree of substitutio n of triphenylamines, the binding of F- to the boron atom led to the appear ance 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 dram atically enhanced upon their oxidation into radical cation (3.0 x 10(5)-1.6 x 10(7)). The fixation of such electroactive compounds to the electrode su rface has been achieved from the anodic oxidation of a vinyl-substituted bi podal receptor. The polymer films showed a reversible and stable response i n a dried organic medium. Unfortunately, the voltammetric changes indicativ e of a complexation phenomenon were not observed in the presence of F- and only a degradation of the film electroactivity was noticed. (C) 2001 Elsevi er Science Ltd. All rights reserved.