Bifunctional chelating agents, their chelates and process of preparation

An 8-substituted-2-carboxamidoquinoline compound having the structure:

• ##STR14## wherein:
• R.sub.2, R.sub.3 and R.sub.4 are identical or different, and are selected from the group consisting of hydrogen, hydroxyl, halogen, C.sub.1 -C.sub.5 alkyl, nitro, nitroso, --SO.sub.3 H, --PO.sub.3 H, and an aryl up to C.sub.18 ;
• X is selected from the group consisting of OH and SH;
• R.sub.5 and R.sub.6 are identical or different, and are selected from the group consisting of hydrogen, a C.sub.1 -C.sub.18 alkyl group which may be unsubstituted or substituted with a member selected from the group consisting of mercapto, carboxy, hydroxy and dialkylamino;
• an aryl up to C.sub.18 which may be substituted with at least one member selected from the group consisting of hydroxy, carboxy amino and mercapto groups;
• and a pyridyl or 8-quinolyl group which may be substituted with a member selected from the group consisting of hydroxy and carboxy;
• the group Q-L represents a substrate coupling moiety, wherein Q is hydrogen, a C.sub.1 -C.sub.18 alkyl group which may be unsubstituted or substituted with the same substituents as R.sub.5 and R.sub.6 above, an aryl and aralkyl up to C.sub.18 pyridyl or 8-quinolyl;
• with the proviso that when Q is hydrogen, L is nonexistent;
• L is a nitro, or an amino group.