title: Ln(iii)-complexes of a DOTA analogue with an ethylenediamine pendant arm as pH-responsive PARACEST contrast agents.
abstract: A novel macrocyclic DO3A derivative containing a linear diamine pendant arm, H3do3aNN, was prepared and its protonation and complexation properties were studied by means of potentiometry. It determined ligand consecutive protonation constants log K(An) = 12.62, 10.28, 9.67, 8.30, 3.30 and 1.58 and stability constants of selected lanthanide (Eu(iii), Yb(iii)) complexes log K(EuL) = 23.16 and log KYbL = 22.76. The complexes could be protonated on the pendant amino group(s) with log K(HLM) ≈ 5.6 and log K(H2LM) ≈ 4.8. Solution structures of both complexes were studied by NMR spectroscopy. The study revealed that the complex species exist exclusively in the form of twisted-square-antiprismatic (TSA) isomers. The complexes show significant pH dependence of the Chemical Exchange Saturation Transfer (CEST) between their amino groups and the bulk water molecules in the pH range of 5-8. Thus, the pH dependence of the magnetization transfer ratio of CEST signals can be used for pH determination using magnetic resonance imaging techniques in a pH range relevant for in vivo conditions.
authors.affiliation: Department of Inorganic Chemistry, Faculty of Science, Universita Karlova (Charles University), Hlavova 2030, 128 43 Prague 2, Czech Republic. modrej@natur.cuni.cz.
authors.forename: T
authors.initials: T
authors.lastname: Krchová
authors.affiliation: Department of Radiodiagnostic and Interventional Radiology, Magnetic Resonance Unit, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague 4, 140 21, Czech Republic.
authors.forename: A
authors.initials: A
authors.lastname: Gálisová
authors.affiliation: Department of Radiodiagnostic and Interventional Radiology, Magnetic Resonance Unit, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, Prague 4, 140 21, Czech Republic and Institute of Biophysics and Informatics, 1st Faculty of Medicine, Universita Karlova (Charles University), Salmovská 1, 120 00 Prague 2, Czech Republic.
authors.forename: D
authors.initials: D
authors.lastname: Jirák
authors.affiliation: Department of Inorganic Chemistry, Faculty of Science, Universita Karlova (Charles University), Hlavova 2030, 128 43 Prague 2, Czech Republic. modrej@natur.cuni.cz.
authors.forename: P
authors.initials: P
authors.lastname: Hermann
authors.affiliation: Department of Inorganic Chemistry, Faculty of Science, Universita Karlova (Charles University), Hlavova 2030, 128 43 Prague 2, Czech Republic. modrej@natur.cuni.cz.
authors.forename: J
authors.initials: J
authors.lastname: Kotek
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005029:Ethylenediamines / Q000737:chemistry*; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D003287:Contrast Media; D005029:Ethylenediamines; D006573:Heterocyclic Compounds, 1-Ring; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; C031234:ethylenediamine