Reinforced Ni(ii)-cyclam derivatives as dual 1H/19F MRI probes

Abstract

Reinforced cross-bridged Ni²⁺-cyclam complexes were functionalised with pendant arms containing both amide protons and CF₃ groups that lead to a dual ¹H/¹⁹F response. The resulting complexes possess very high inertness favourable for MRI applications. The paramagnetism of the Ni²⁺ ion shifts the amide resonance 56 ppm away from bulk water favouring the chemical exchange saturation transfer (CEST) effect and shortening the acquisition times in ¹⁹F magnetic resonance imaging (MRI) experiments, thus enhancing the signal-to-noise ratios compared to the fluorinated diamagnetic reference.