Patent ID: 8747810

Claim:
A compound represented by the formula: or a complex represented by the formula: wherein: X is a linking group comprising an aliphatic backbone chain having 1 to about 8 atoms, in which the aliphatic backbone chain optionally includes ester, amide, ether or thioether linkages in the aliphatic backbone chain; and R 1 and R 2 each are independently selected from the group consisting of hydrogen, unsubstituted alkyl groups having from 1 to about 8 carbon atoms, alkoxyalkyl group having from 2 to about 8 carbon atoms, and substituted alkyl or alkoxyalkyl groups having from 1 to about 8 carbon atoms which are substituted with one or more groups selected from optionally substituted aryl, optionally substituted cycloalkyl, optionally substituted heteroalicyclic, and optionally substituted heteroaryl; or wherein R 1 and R 2 taken together with the nitrogen atom to which they are attached form a heterocyclic ring having from 3 to 8 atoms in the ring; or one of R 1 or R 2 is alkyl and the other is a moiety selected from: in which Y represents 0-4 substituents independently selected from halogen, alkyl, alkoxyl, or cyano; or a salt thereof; wherein M is a metal selected from technetium and rhenium.