Iodinated Metallacrowns: Toward Combined Bimodal Nearâ Infrared and Xâ Ray Contrast Imaging Agents

Abstract

Multimodal probes capable of combining imaging modalities within a single molecule are in high demand today as they can provide information at both molecular and anatomical levels. Herein, a study was conducted on a series of gallium(III)/lanthanide(III) bis(12â MCâ 4) metallacrowns (MCs) with the general composition {Ln[12â MCGaIIIN(shi)â 4]}2(iph)4 (Lnâ Ix, x=0, 4, 8, 12), where shi and iph are salicylhydroximate and isophthalate ligands, respectively, or their iodinated derivatives. For Ybâ Ix, the attenuation in Xâ ray computed tomography (XCT) imaging and nearâ infrared (NIR) luminescence properties can be finely tuned by controlled structural modifications based on iodo groups. Solutions of Ybâ Ix appear to be 22â 40 times more efficient as XCT agents in comparison to the commercially available iobitridol, while providing an intense emission signal in the NIR range with total quantum yields up to 8.6â %, which are among the highest values reported so far. Therefore, these molecules are promising potential bimodal agents for combined NIR luminescence and XCT imaging.A new family of iodinated ytterbium(III)â gallium(III) metallacrowns with tunable Xâ Ray attenuation and nearâ infrared luminescence has been created.