Reactive oxygen species (ROS) such as the hydroxyl radical are generated upon incomplete reduction of molecular dioxygen.1 ROS play essential roles in important physiological processes such as signalling and immune response. 1,2 The uncontrolled production of these species can however leads to oxidative stress, which is believed to be the origin of major pathologies, including cancer and neurodegenerative diseases.3 The design of redox active probes for the signalling of excessive ROS species is a fascinating target. Lanthanide complexes have fascinating optical and magnetic properties which have already been exploited in medical imaging and could be potential targets for use in vivo.2 A major problem with the use of LnIII in the detection of oxidative stress is the marked tendency of the lanthanides to exist in their 3+ oxidation state in physiological conditions. They thus cannot be used as intrinsic detectors of redox processes. Our approach focuses on the design and synthesis of novel pro-radical ligands and their incorporation into complexes which, when oxidised independently of the metal ion, produce an easily detectable change in the complex properties. We report herein a series of novel DOTA type lanthanide complexes containing a redox non-innocent ligand nitroxide and a-iminohydroxylamine, capable of inducing a magnetic and luminescent response from the coordinated lanthanide ion.3,4 These complexes and their response have been studied via electrochemistry, EPR, UV-vis and luminescent spectroscopy and CEST spectroscopy and NMRD.