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Aryl‐Phosphonate Lanthanide Complexes and Their Fluorinated Derivatives: Investigation of Their Unusual Relaxometric Behavior and Potential Application as Dual Frequency 1 H/ 19 F MRI Probes
Author(s) -
Placidi Matteo P.,
Botta Mauro,
Kálmán Ferenc K.,
Hagberg Gisela E.,
Baranyai Zsolt,
Krenzer Andreas,
Rogerson Alexandria K.,
Tóth Imre,
Logothetis Nikos K.,
Angelovski Goran
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300763
Subject(s) - chemistry , lanthanide , phosphonate , relaxometry , nuclear magnetic resonance spectroscopy , spectroscopy , relaxation (psychology) , intramolecular force , analytical chemistry (journal) , coordination sphere , crystallography , nuclear magnetic resonance , ion , stereochemistry , crystal structure , organic chemistry , medicine , social psychology , psychology , physics , spin echo , quantum mechanics , magnetic resonance imaging , radiology
A series of low molecular weight lanthanide complexes were developed that have high 1 H longitudinal relaxivities ( r 1 ) and the potential to be used as dual frequency 1 H and 19 F MR probes. Their behavior was investigated in more detail through relaxometry, pH‐potentiometry, luminescence, and multinuclear NMR spectroscopy. Fitting of the 1 H NMRD and 17 O NMR profiles demonstrated a very short water residence lifetime (<10 ns) and an appreciable second sphere effect. At lower field strengths (20 MHz), two of the complexes displayed a peak in r 1 (21.7 and 16.3 m M −1 s −1 ) caused by an agglomeration, that can be disrupted through the addition of phosphate anions. NMR spectroscopy revealed that at least two species are present in solution interconverting through an intramolecular binding process. Two complexes provided a suitable signal in 19 F NMR spectroscopy and through the selection of optimized imaging parameters, phantom images were obtained in a MRI scanner at concentrations as low as 1 m M . The developed probes could be visualized through both 1 H and 19 F MRI, showing their capability to function as dual frequency MRI contrast agents.