Synthesis and characterization of α-hexadecyl-DOTA and its Gd(III) chelate

Synthesis and characterization of the ligand. 10-(α-hexadecylarboxyethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H₄L), and its Gd(III) chelate are described. Protonation constants for H₄L (lg K_i^H = 10.52, 9.45, 4.74, 4.10) and the stability constant for GdL⁻ (lg K_GdL- =24.50) were determined by potentiometric titrations. The results obtained show that the ligand still maintains the strong chelating properties of the parent DOTA (1,4,7,10-tetraazacyclododecae-N,N′,N′'N′-tetraacetic acid) after introduction of a linear chain hexadecyl group at the acetic side chain of DOTA, and its basicity is not significantly altered.