Thermodynamic and structural properties of Gd3+ complexes with functionalized macrocyclic ligands based upon 1,4,7,10-tetraazacyclododecane

• DOI: 10.1039/a909098c
• Publication Date: 2002-07-26T09:06:44Z
• Authors: Antonio Bianchi; Luisella Calabi; Claudia Giorgi; Pietro Losi; Palma Mariani; Paola Paoli; Patrizia Rossi; Barbara Valtancoli; Mario Virtuani
• Keywords: DOTA; Chemical Stability

The co-ordination properties toward Na+, Ca2+, Zn2+, Cu2+ and Gd3+ of six ligands containing pendant functionalities attached to the common 1,4,7,10-tetraazacyclododecane macrocyclic ring have been studied by means potentiometric microcalorimetric methods. Stability constants for 1,4,7,10-tetra(methylcarbamoylmethyl) ligand (DTMA), new 10-(2-hydroxypropyl) 1,4,7-tri(2-hydroxymethylacetic acid) (HPDO3A-3HM) (DO3A-3HM) are reported first time, while analogous data remaining redetermined under same experimental conditions (0.1 mol dm−3 NMe4Cl, 298.1 ± 0.1 K). synthesis DTMA is also described. stability GdL complexes follows order DOTA (1,4,7,10-tetraacetic ≈ HPDO3A [10-(2-hydroxypropyl) 1,4,7-triacetic acid] > DO3A (1,4,7-triacetic HPDO3A-3HM DO3A-3HM DTMA, although considering both complex formation basicity binding selectivity these at physiological pH DTMA. thermodynamic resistance complexes, a plasma concentration clinical administrations, demetallation in presence important components blood plasma, such as Cu2+, phosphate carbonate, has evaluated: results consistent with previous trend selectivity. intermediate complexed species formed minutes complexation reactions from point view. crystal structure [Gd(DTMA)(H2O)][ClO4]3·NaClO4·3H2O, solved X-ray analysis, displays ion 9-co-ordinated environment defined four nitrogens tetraazamacrocyclic moiety, eight amidic oxygen atoms side arms an atom water molecule.