ELECTRODE MODIFIED BY SULFONATED CALIXARENES IMMOBILIZED INTO A POLYPYRROLE FILM - A STEP TOWARDS NEW ION-SENSITIVE LAYERS

Sulfonated calixarenes, calix[4]-p-tetrasulfonate and calix[6]-p-hesas ulfonate have been included as dopants into polypyrrole films during t heir electrodeposition at the surface of a glassy carbon electrode. Ta king into account the bulkiness of these cage molecules, they are irre versibly immobilized into the polypyrrole matrix. The complexation of the guest trimethyl(ferrocenylmethyl) ammonium cation, FcTMA(+) by the se sulfonated calixarenes in solution has been used as a model host/gu est reaction to detect the specific entrapment of the FcTMA(+) cation into the functionalized polypyrrole coating. The shift of the redox po tential of the FcTMA(+) after complxuing in solution or entrapping int o the film are very close. This confirms that the polypyrrole affinity for the FcTMA(+) cation is due to the specific recognition by the fre e cavity of the included sulfonated calixarenes.