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Manganese(II) Complexes as Potential Contrast Agents for MRI
Author(s) -
Drahoš Bohuslav,
Lukeš Ivan,
Tóth Éva
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201101336
Subject(s) - chemistry , denticity , ligand (biochemistry) , outer sphere electron transfer , manganese , molecule , coordination sphere , unpaired electron , chelation , chemical stability , redox , inner sphere electron transfer , chemical physics , computational chemistry , ion , combinatorial chemistry , inorganic chemistry , crystallography , crystal structure , organic chemistry , biochemistry , receptor
Mn 2+ has five unpaired d electrons, a long electronic relaxation time, and labile water exchange, which make it an attractive alternative to Gd 3+ in the design of contrast agents for medical Magnetic Resonance Imaging. In order to ensure in vivo safety and high contrast agent efficiency, the Mn 2+ ion has to be chelated by a ligand that provides high thermodynamic stability and kinetic inertness of the complex and has to have at least one free coordination site for a water molecule. Unfortunately, these two requirements are contradictory, as lower denticity of the ligands, which leads to more inner‐sphere water molecules often implies a decreased stability of the complex, and, therefore, it is necessary to find a balance between both requirements. In the last decade, a large amount of experimental data has been collected to characterize the physico‐chemical properties of Mn 2+ chelates with variable ligand structures. They now allow for establishing trends of how the ligand structure, the rigidity of the ligand scaffold, and its donor–acceptor properties influence the thermodynamic, kinetic, and redox stability of the Mn 2+ complex. This microreview surveys the current literature in this field.