Easy access to heterobimetallic complexes for medical imaging applications via microwave-enhanced cycloaddition

The Cu(I)-catalysed Huisgen cycloaddition, known as ``click'' reaction, has been applied to the synthesis of a range of triazolel-inked porphyrin/corrole to DOTA/NOTA derivatives. Microwave irradiation significantly accelerates the reaction. The synthesis of heterobimetallic complexes was easily achieved in up to 60% isolated yield. Heterobimetallic complexes were easily prepared as potential MRI/PET (SPECT) bimodal contrast agents incorporating one metal (Mn, Gd) for the enhancement of contrast for MRI applications and one ``cold'' metal (Cu, Ga, In) for future radionuclear imaging applications. Preliminary relaxivity measurements showed that the reported complexes are promising contrast agents (CA) in MRI.