Synthesis of a rigidified bicyclic AAZTA-like ligand and relaxometric characterization of its GdIII complex. Issue 48 (26th November 2020)

• Record Type: Journal Article
• Authors: Martinelli, Jonathan; Martorana, Enrico; Tei, Lorenzo
• Is Part Of: Tetrahedron letters. Volume 61:Issue 48(2020)
• Publication Date: 2020-11-26
• Subjects: MRI Contrast agents -- Gadolinium -- Chelating ligands -- Conformational Rigidity -- Relaxivity; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2020.152573
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: The synthesis and characterization of novel polydentate ligand CpAAZTA is reported. In CpAAZTA a torsionally-strained cyclopentane replaces the AAZTA ethylene bridge. Its rigid Gd-complex shows high inertness and excellent physico-chemical properties. Abstract: The synthesis of a novel constrained polydentate ligand CpAAZTA derived from the heptadentate polyaminocarboxylic ligand AAZTA (6-amino-6-methylperhydro-1, 4-diazepine- N, N ', N '', N ''-tetraacetic acid) in which the ethylene bridge of the 1, 4-diazepine ring is replaced by a cyclopentyl bridge is reported. In order to compare the effect of the different size and rigidity induced on the chelate by a 5-membered ring vs . a previously-reported cyclohexane-derivative, the relaxivity of the corresponding bis-hydrated Gd III complex was also investigated as a function of the magnetic field, temperature and pH.