Structural isomerism in gold nanoparticles revealed by X-ray crystallography

Revealing structural isomerism in nanoparticles using single-crystal X-ray crystallography remains a largely unresolved task, although it has been theoretically predicted with some experimental clues. Here we report a pair of structural isomers, Au 38T and Au 38Q , as evidenced using electrospray ionization mass spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis and indisputable single-crystal X-ray crystallography. The two isomers show different optical and catalytic properties, and differences in stability. In addition, the less stable Au 38T can be irreversibly transformed to the more stable Au 38Q at 50 °C in toluene. This work may represent an important advance in revealing structural isomerism at the nanoscale.