Patent ID: 8211401

Claim:
A compound of Formula I, a pharmaceutically acceptable salt thereof: wherein R is H, an ammonium ion, an alkylammonium ion, an alkaline earth metal ion, a rare earth metal ion, or an alkyl group; W is a bond, —NHC(O)—, —CH(NH 2 )—, —NH—C(O)—NH—, —C(O)—NH—, —C(O)—NH—CH(COOH)—, —O—(CH 2 ) n —O—(CH 2 ) n -, —(CH 2 ) n O(CH 2 ) n O(CH 2 ) n -, —CH(NHFmoc)-; Z is a bond, —CO(O)—, —NH—, —NHC(O)—, —NH—C(O)—NH—, —NH—C(O)—(CH 2 ) n -, —NH—C(O)—CH(NH 2 )—, —C(O)—NH—CH(COOH)—; or —NH—C(O)—C 6 H 4 -(CH 2 ) n —NH—; NR a R b is a chelator group of Formula: R t is H, a C 1 -C 8 alkyl group, an ammonium ion, an alkylammonium ion, or an alkali or alkaline earth metal ion; R v is alkyl; e is an integer from 0 to 15; f is an integer from 0 to 15; g is an integer from 0 to 15; and n is an integer from 0 to 10.