Room temperature synthesis and Raman spectral evidence of carbon bond ranelate–gold nanoparticles

Ranelate ions, employed in the past as strontium salt for the treatment of osteoporosis, exhibit a rather interesting chemistry associated with a central thiophene ring encompassing two carboxylic groups, a cyanonitrile substituent, and a nitrile diacetate group. In spite of their unfavorable reduction potentials, around 1.26 V, they react very rapidly with HAuCl4 at room temperature, leading to decarboxylation at the C5 position in order to generate gold nanoparticles strongly stabilized by Au–C bonds. The reactions were elucidated by electrospray ionization mass spectrometry, ligand exchange kinetics, and by means of the surface‐enhanced Raman scattering effect. The gold nanoparticles were further characterized based on transmission electron microscopy and CytoViva hyperspectral microscopy. Ranelate ions react at room temperature with HAuCl4, yielding gold nanoparticles that were characterized by means of dark field CytoViva hyperspectral microscopy, ESI MS, and ligand exchange kinetics; their great stability support the formation of strong Au–C bonds, compatible with the SERS spectra exhibiting a characteristic peak at 437 cm−1.