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Balogh, E ; He, Z ; Hsieh, W ; Liu, S ; Tóth, E

Dinuclear Complexes Formed with the Triazacyclononane Derivative ENOTA4-. High Pressure 17O NMR evidence of an associative water exchange on [MnII2(ENOTA)(H2O)2].

Inorganic Chemistry 46 (1) 238-250

par Administrateur - publié le

Abstract :

Mn2+ has five unpaired d-electrons, a long electronic relaxation time, and labile water exchange, all of which make it an attractive candidate for contrast agent application in medical magnetic resonance imaging. In the quest for stable and nonlabile Mn2+ complexes, we explored a novel dimeric triazacyclononane-based ligand bearing carboxylate functional groups, H(4)ENOTA. The protonation constants of the ligand and the stability constants of the complexes formed with some endogenously important metals (Ca2+, Cu2+, Zn2+), as well as with Mn2+ and Ce3+, have been assessed by NMR methods, potentiometry, and UV-vis spectrophotometry.