The invention relates to a compound corresponding to general formula (I) wherein n is a whole number from 1-6, m is a whole number equal to 5, 6 or 7, R.sup.1 is an OH group, all R.sup.1s are identical, Z is an NHX group, X is a hydrogen atom, and R is a hydrogen atom or a bioidentification element, with the proviso that the compound wherein n=1, m=6, Z=NH.sub.2 and R.sub.1=OH is excluded.