Patent ID: 7727512

Claim:
A compound of the formula: wherein Ch represents a chelating moiety selected from the group consisting of porphyrins, ethylenediaminetetraacetic acid (EDTA), diethylenetriamine-N,N,N′,N″,N″-pentaacetate (DTPA), 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7 (ODDA), 16-diacetate,N-2-(azol-1(2)-yl)ethyliminodiacetic acids, 1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA), 1,7,13-triaza-4,10,16-trioxacyclo-octadecane-N,N′,N′″-triacetate (TTTA), tetraethylene glycols, 1,5,9-triazacyclododecane-N,N′,N″-tris(methylenephosphonic acid (DOTRP), and N,N′,N″-trimethylammonium chloride (DOTMA); m is 0-3; each R 1 is independently a non-interfering substituent selected from the group consisting of halo, OR, NR 2 , SR, CN, NO 2 , SO 3 H, and R where R is alkyl or alkenyl optionally substituted by halo, or ═O, and optionally containing a heteroatom, such as O, S or N; 1 is 0-2; Z is S or O; R 2 is H or alkyl (1-4C); n is 1; and each R 3 is independently an optionally substituted saturated or unsaturated hydrocarbyl group containing at least 10 C; and spacer is —CH 2 CH 2 — and/or includes a peptide, a pseudopeptide, or a polyalkylene glycol, optionally containing a cleavage site.