1. Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074, China 2. Department of Chemistry and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, China 3. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
Abstract：To look for new MRI (magnetic resonance imaging) contrast agents with higher relaxivity as well as liver-selecsivity, four novel ester-amino ligands were synthesized by bis-acylation of octadecanyl, hexadecanyl, tetradecanyl and dedecanyl L-lysine with diethylenetriaminepentaacetic acid mono-anhydride (DTPA-MA), respectively. The corresponding dimeric Gd(Ⅲ) complexes were gained by the reaction of these ligands with GdCl3·6H2O. All ligands and complexes were characterized by FTIR, 1H NMR and elemental analysis. The longitudinal relaxation time (T1) was measured, and relevant longitudinal relaxivity (R1) of these neatral binuclear Gd(Ⅲ) complexes is: 6.48, 6.02, 5.76 and 5.68 L·mmol-1·s-1,respectively, and all are higher than that of Gd-DTPA (4.98 L·mmol-1·s-1)(300 MHz).
Key words：MRI;Dimeric contrast agent;Ester of L-lysine;Amphiphilicity;Gadolinium complex;Longitudinal relaxivity(R1)
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