Seven-coordinate Co(II), Fe(II) and six-coordinate Ni(II) amide-appended macrocyclic complexes as ParaCEST agents in biological media.

ABSTRACT: The solution chemistry and solid-state structures of the Co(II), Fe(II), and Ni(II) complexes of 7,13-bis(carbamoylmethyl)-1,4,10-trioxa-7,13-diazacyclopentadecane (L) are reported as members of a new class of paramagnetic chemical exchange saturation transfer (paraCEST) MRI contrast agents that contain transition metal ions. Crystallographic data show that nitrogen and oxygen donor atoms of the macrocyclic ligand coordinate to the metal ions to generate complexes with distorted pentagonal bipyramidal geometry for [Co(L)]Cl2·2H2O or [Fe(L)](CF3SO3)2. The Ni(II) complex [Ni(L)](CF3SO3)2·H2O features a hexadentate ligand in a distorted octahedral geometry. The proton NMR spectra of all three complexes show highly dispersed and relatively sharp proton resonances. The complexes were further ch

SUBMITTER: Olatunde AO 

PROVIDER: S-EPMC4139174 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature