Chealators of type XN.sub.1 S.sub.1 X.sup.1 for radioactive isotopes, their metal complexes and their diagnostic and therapeutical uses

A conjugate containing a compound with a substance that accumulates selectively in diseased tissues, a covalent bond existing between the compound and the substance, said bond being amidic if the substance contains carboxy or amino groups including a peptide, a protein, an antibody, or a fragment thereof, ester-like if the substance contains hydroxy groups including a fatty alcohol, and imidic if the substance contains aldehyde groups, the compound having the general formula (I)

• B--CO--CR.sup.1 R.sup.2 --A--CR.sup.3 R.sup.4 --CR.sup.5 R.sup.6 --A'--R.sup.12 (I)
• wherein
• A,A' are same or different and represent an O, S, or Se chalcogen atom,
• R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, and R.sup.6 are same or different and represent a hydrogen atom or a branched or unbranched C.sub.1 -C.sub.6 alkyl residue,
• B represents a residue
• --NH--(CR.sup.7 R.sup.8)--(CR.sup.9 R.sup.10).sub.n=1,2 --S--R.sup.11,
• wherein
• R.sup.7 and R.sup.8 are same or different and represent a hydrogen atom or an unbranched, branched, cyclic, or polycyclic C.sub.1 -C.sub.60 alkyl, alkenyl, polyalkenyl, alkinyl, polyalkinyl, aryl, alkylaryl, or arylakyl residue which may optionally carry additional hydroxy, oxy, oxo, carboxy, aminocarbonyl, alkoxycarbonyl, amino, aldehyde, or alkoxy groups containing up to 20 carbon atoms, and may optionally be interrupted, or replaced, by one or several heteroatoms from the series of O, N, S, P, As, Se,
• R.sup.9 and R.sup.10 are same or different and represent a hydrogen atom or a branched or unbranched C.sub.1 -C.sub.6 alkyl residue,
• R.sup.11 represents a hydrogen atom, a sulfur protecting group, or residues R.sup.7 or R.sup.8, or with R.sup.7 and R.sup.11, together with --(CR.sup.8)--(CR.sup.9 R.sup.10).sub.n=1,2 --S--, forming a 4- to 8-membered ring which may optionally carry additional hydroxy, oxo, oxy, or alkoxy groups containing up to 6 carbon atoms,
• R.sup.12 represents a hydrogen atom or chalcogen protecting group;
• and a complex of the conjugate with a radioisotope of Tc or Re.