Synthesis and characterization of new polyethyleneoxy substituted salicylaldimine Schiff bases and some corresponding reduced tetra- and penta-aza ligands and their gadolinium(III) complexes: new potential contrast agents in magnetic resonance imaging

A series of polyether substituted salicylaldehyde derivatives OHCC6H3OH-2-OR-3 [R = CH2(CH2OCH2)nCH2OR′, n= 1, 4 and R′= Me; n= 5 and R′= H] have been synthesised and used to prepare the polydentate ligands HN[(CH2CH2NHCH2CH2NCHC6H3OH-2-OR-3]2,HN[CH2CH2NHCH2CH2NHCH2C6H3-OH-2-OR-3]2 and HN[CH2CH2NCHC6H3OH-2-OR-3]3; a preliminary evaluation has been made of the potential use of their gadolinium complexes as contrast agents for diagnostic Magnetic Resonance Imaging.