Metal ion-ligand coordination complexes, antibodies directed thereto, and assays using such antibodies

A compound having a structure selected from the group consisting of ##STR1## Where r is selected from the group consisting of --CH.sub.2 --(CH.sub.2).sub.2 --(C(CH.sub.3).sub.2)

• Y and Z can be the same or different and are selected from the group consisting of --H --CO.sub.2 H --SO.sub.3 H
• X is selected from the group consisting of --OH--OR.sub.1 --NHR.sub.2 --NHR.sub.3
• R.sub.1 is C.sub.1 -C.sub.4 alkyl or ##STR2## R.sub.2 is C.sub.1 -C.sub.4 alkyl R.sub.3 is C.sub.1 -C.sub.10 alkyl contributed by a conjugate molecule
• provided that r cannot be CH.sub.2 or (CH.sub.2).sub.2 in L.sub.5, further provided that r cannot be CH.sub.2 when X is OH in L.sub.6, and further provided that r cannot be CH.sub.2 in L.sub.8.