title: Density-functional theory structures of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complexes for ions across the lanthanide series.
abstract: The use of organically chelated lanthanides in diagnosis and treatment is a rapidly growing field in medicine. In order to gain a deeper understanding into the properties of these chelates, particularly spectroscopic, density-functional calculations have been performed on a series of lanthanide ions chelated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid. Based on the results of these calculations, it has been concluded that the local symmetry experienced by the chelated lanthanide ion may be treated as being axial, which will make the interpretation of their spectroscopic properties greatly simplified. It has also been suggested that the so-called "capping" water molecule at the ninth coordination position of the lanthanide is hydrogen bonded to the acetate oxygens of the sidearms, rather than coordinated as the ninth ligand of the lanthanide.
authors.affiliation: Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Lidia
authors.initials: L
authors.lastname: Smentek
authors.forename: B
authors.initials: B
authors.lastname: Andes Hess
authors.forename: Jason P
authors.initials: JP
authors.lastname: Cross
authors.forename: H
authors.initials: H
authors.lastname: Charles Manning
authors.forename: Darryl J
authors.initials: DJ
authors.lastname: Bornhop
mesh_terms: D002614:Chelating Agents / Q000494:pharmacology*; D004581:Electronics; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D006860:Hydrogen Bonding; D007477:Ions; D028581:Lanthanoid Series Elements; D008024:Ligands; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D012984:Software; D013053:Spectrophotometry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D006573:Heterocyclic Compounds, 1-Ring; D007477:Ions; D028581:Lanthanoid Series Elements; D008024:Ligands; D014867:Water; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D009584:Nitrogen; D010100:Oxygen