Improving the potential of paraCEST through magnetic-coupling induced line sharpening

Magnetic coupling between paramagnetic centers is a crucial phenomenon in the design of efficient MRI contrast agents. In this study, we investigate the paraCEST properties and magnetic coupling effects of a novel homodinuclear Ni(ii) complex, 1, containing a Robson type macrocyclic ligand. A thorough analysis of the complex's electronic and magnetic properties revealed that the magnetic coupling effect reduces the transverse relaxation rate and enhances the sharpness of the proton resonances, leading to enhanced CEST efficiency. This novel mechanism, which we coined magnetic-coupling induced line sharpening (MILS), can be crucial for optimizing the performance of paramagnetic metal complexes in paraCEST imaging. Moreover, magnetic coupling plays a critical role in the relaxation properties of homodinuclear complexes. Our study not only paves the way for the creation of advanced paraCEST agents with enhanced CEST capabilities and sensitivity but also provides valuable guidance for the design of other MRI contrast agents utilizing dinuclear metal complexes. A paramagnetic chemical exchange saturation transfer (paraCEST) imaging agent based on a homodinuclear Ni(ii) complex exhibits enhanced CEST efficiency due to magnetic-coupling induced line sharpening effect.

Automated summary

This study investigates the magnetic-coupling effects and paraCEST properties of a homodinuclear Ni(ii) complex, showing that magnetic coupling reduces relaxation rate and enhances proton resonances, resulting in enhanced CEST efficiency. The study reveals the crucial role of magnetic coupling in optimizing the performance of paramagnetic metal complexes and provides guidance for the design of other MRI contrast agents.