A d-f heteronuclear complex for dual-mode phosphorescence and magnetic resonance imaging

A d-f heteronuclear complex (Ir–Gd) by coupling an iridium(III) complex to a macrocycle-based gadolinium complex has been developed as as a dual-mode bioimaging probe for luminescence imaging and magnetic resonance imaging (MRI). The cyclometalated iridium complex showed an intense visible metal-to-ligand charge transfer (MLCT) absorption and strong yellow phosphorescent luminescence. It has specificity of staining in murine mitochondria confirmed by confocal laser scanning microscopy. The macrocycle-based gadolinium complex provides the longitudinal relaxivity of 3.36 mm−1s−1 on a 3 T system, which has been applied to MRI for liver in mice. Furthermore, the biodistribution of Ir–Gd has been investigated using inductively coupled plasma–atomic emission spectroscopy (ICP-AES) analyses. Such platform should be extended to further applications in the identification and diagnosis of liver diseases.