The invention relates to novel pyrrole derivatives of the formula (I) which make it possible to immobilize and address oligonucleotides by electropolymerization. Said invention also relates to thus produced electroactive polymers and to methods for using them for detecting, identifying and dosing analytes in a sampe. (I) wherein R.sub.1 is one type of oligonucleotide, Y is S or O, X is a spacer arm selected from --(CH.sub.2)--O--, --(CH.sub.2)PO--[(CH.sub.2).sub.2--O].sub.q--, --(CH2.sub.)r; --CO--NR--(CH.sub.2)r-0-, --CH.sub.2r--NCH.sub.3--(CH.sub.2).sub.r--O--, --CH.sub.2).sub.rCO--NR'--[CH.sub.2).sub.2--O].sub.s--, --(CH.sub.2).sub.rNCH.sub.3[(CH.sub.2).sub.2--O]S--, R' is H or CH.sub.3, n is an integer number ranging from 1 to 5, p is an integer number ranging from 1 to 2, q is an integer number ranging from 1 to 4, r is an integer number ranging from 1 to 3, r' is an integer number ranging from 1 to 3, s is an integer number ranging from 1 to 3, n, p, q, r, r' and s are identical or different, a pyrrole cycle is substituted in a position 2, 3, 4 or 5.