"The composition of claim 46, wherein the molecule has the formula ##STR46## wherein if R1 is an aryl group, then R2 is a hydrogen; heterocyclic; alkyl; aryl, or a phenyl group, the phenyl group optionally being substituted with an alkyl, halo, amino, or a thiol group; andif R2 is an aryl group, then R1 is hydrogen; heterocyclic; alkyl; aryl, or a phenyl group, the phenyl group optionally being sub" . . . .