Design of organoruthenium complexes for nanoparticle functionalization

In recent years, extensive research efforts have been focused on loading metal complexes onto macromolecular systems such as nanoparticles. We report a ligand with a catechol group based on a picolinamide which allows for coordination to organoruthenium moieties while the catechol group remains available for loading on nanoparticles as delivery vehicles towards tumors. All the compounds were characterized with standard analytical methods and the molecular structure of the ligand 1, and its Ru complexes 1a and 1b were determined by X-ray diffraction analysis. The crystal structure of 1a and 1b showed pseudo-tetrahedral geometry of the Ru center with “piano-stool” conformation and 1 coordinated as an N,O-bidentate ligand, however, the latter depending on the reaction conditions employed. The Ru complexes 1a–1c were effectively loaded on magnetite nanoparticles as characterized by inductively-coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR).