BIFUNCTIONAL CHELATING AGENTS

A chelating agent, a metal-chelate, and a contrast agent are provided, wherein the chelating agent comprises a compound of structure (I) wherein R1, R2, R3, R8, R7, R′7 R′1, R′2, R′3 and R8′ are selected from a hydrogen, a protected C1-C3 hydroxyalkyl group, a C1-C3 alkyl group; R4 and R′4 are selected from a hydrogen, a hydroxyl group, a protected hydroxy group, a protected C1-C3 hydroxyalkyl group, a C1-C3 alkyl group; n is an integer between 0 and 4; R5 and R′5 are selected from a hydrogen, a protecting group selected from the group consisting of C1-C30 aliphatic radicals, C3-C30 cycloaliphatic radicals, C2-C30 aromatic radicals; R9 and R′9 are selected form a hydrogen or a protecting group selected from the group consisting of C1-C30 aliphatic radicals, C3-C30 cycloaliphatic radicals, C2-C30 aromatic radicals, m is an integer between 0 and 10; and at least one of R7 and R′7 is acidic group or a protected acidic group.