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-hexas 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 th ese sulfonated calixarenes in solution has been used as a model host/g uest reaction to detect the specific entrapment of the FcTMA(+) cation into the functionalized polypyrrole coating. The shift of the redox p otential of the FcTMA(+) after complexing in solution or entrapping in to the film are very closed. This confirms that the polypyrrole affini ty for the FcTMA(+) cation is due to the specific recognition by the f ree cavity of the included sulfonated calixarenes.