Patent ID: 7456215

Claim:
A complex comprising a metal ion and a compound represented by structural formula I: 2-OH—Ar—CR 1 —NR 2 —R 3 —COOH I wherein 2-OH—Ar is an optionally substituted 2-hydroxyaryl; R 1 is —OH or ═O; R 2 is hydrogen, hydroxyl or an optionally substituted C 1 -C 4 alkyl, C 1 -C 4 alkoxy, or C 2 -C 4 alkenyl; and R 3 is an optionally substituted aryl, heteroaryl, cycloalkyl, heterocyclyl, C 1 -C 24 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynl, C 1 -C 10 alkylaryl, C 1 -C 10 arylalkyl, C 2 -C 10 alkenylaryl, C 2 -C 10 arylalkenyl, C 2 -C 10 alkynylaryl or C 2 -C 10 arylalkynyl, which optionally is interrupted by O, N, S or any combination thereof.