title: Toward the Prediction of Water Exchange Rates in Magnetic Resonance Imaging Contrast Agents: A Density Functional Theory Study.
abstract: We present a theoretical investigation of Gd-Owater bonds in different complexes relevant as contrast agents in magnetic resonance imaging (MRI). The analysis of the Ln-Owater distances, electron density (ρBCP), and electron localization function (ELF) at the bond critical points of [Ln(DOTA)(H2O)](-) and [Ln(DTPA-BMA)(H2O)] indicates that the strength of the Ln-Owater bonds follows the order DTPA-BMA > DOTA (M isomer) > DOTA (m isomer). The ELF values decrease along the 4f period as the Ln-Owater bonds get shorter, in line with the labile capping bond phenomenon. Extension of these calculations to other Gd(3+) complexes allowed us to correlate the experimentally observed water exchange rates and the calculated ρBCP and ELF values. The water exchange reaction becomes faster as the Gd-Owater bonds are weakened, which is reflected in longer bond distances and lower values of ρBCP and ELF. DKH2 calculations show that the two coordinated water molecules may also have significantly different (17)O hyperfine coupling constants (HFCCs).
authors.affiliation: †Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain.
authors.forename: Martín
authors.initials: M
authors.lastname: Regueiro-Figueroa
authors.affiliation: †Departamento de Química Fundamental, Universidade da Coruña, Campus da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Platas-Iglesias
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D019786:Gadolinium DTPA / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008536:Meglumine / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D014867:Water; D008536:Meglumine; C064925:gadodiamide; D005682:Gadolinium; D019786:Gadolinium DTPA; C072417:gadoterate meglumine