Synthesis of AuNC stabilized by F27SH and crystallization of [Au25(SF27)18]0. a Cartoon representation of AuNC stabilized by F27SH thiol. For the sake of clarity, only 6 F27S-ligands have been reported; b schematic representation of crystal formation in solkane solution and colorimetric change upon their dissolution in PFO; c UV–Vis spectra of crude product in solkane and crystals redissolved in PFO; d, e STEM images of crude product showing the presence of small clusters and bigger AuNPs; f, g STEM images of redissolved crystals solution showing the homogeneous presence of small clusters. Credit: Nature Communications (2022). DOI: 10.1038/s41467-022-29966-2
The SupraBioNano Lab (SBNLab)at the Politecnico di Milano’s Department of Chemistry, Materials and Chemical Engineering “Giulio Natta,” in partnership with the University of Bologna and the Aalto University of Helsinki (Finland) has, for the first time, synthesized a superfluorinated gold nanocluster, made up of a core of only 25 gold atoms, to which 18 branch-structured fluorinated molecules are linked. The project was recently published in Nature Communications.
The metal clusters are an innovative class of very complex nanomaterial, characterized by ultra-small dimensions (<2nm) and peculiar chemical-physical properties such as luminescence and catalytic activity, which encourage its application in various scientific fields of high importance in relation to modern global challenges. These include precision medicine, in which metal nanoclusters are used as innovative probes for diagnostic and therapeutic applications, and the energy transition, where they are applied as efficient catalyzers for the production of green hydrogen.
The crystallization of metal nanoclusters offers the possibility of obtaining high-purity samples, allowing their fine atomic structure to be determined; however, at present this remains a very difficult process to control. The methodologies developed in this study promoted the crystallization of nanoclusters, allowing their atomic structure to be determined by means of X-ray diffraction at the Sincrotrone Elettra in Trieste. The end result is the structural description of the most complex fluorinated nano-object ever reported.
“Thanks to the presence of a completely fluorinated shell, containing almost 500 fluorine atoms, the gold nanocluster is stabilized by the numerous interactions between the fluorine atoms of the binder, encouraging crystallization,” says professor Giancarlo Terraneo.
“It will soon be possible to study the structure of these advanced nanomaterials at the Politecnico di Milano, where—thanks also to the grant from the Region of Lombardy—Next-GAME (Next-Generation Advanced Materials), a laboratory dedicated to the use of state-of-the-art X-ray instruments to characterize crystals, nanoparticles and colloids, is being established,” says professor Pierangelo Metrangolo, on behalf of Next-GAME.
The interactions between the fluorine atoms both within the nanocluster and between the nanoclusters were rationalized using quantum chemistry techniques at the University of Bologna’s “G. Ciamician” Chemistry Department by Dr. Angela Acocella and professor Francesco Zerbetto.
Professor Valentina Dichiarante, professor Francesca Baldelli Bombelli, Dr. Claudia Pigliacelli and professor Giulio Cerullo, from the Politecnico di Milano’s Physics Department, also contributed to the study, looking at the nanocluster’s optical characteristics and demonstrating the fluorinated binders’ impact on the gold core’s optical activity.
Further information: Claudia Pigliacelli et al, High-resolution crystal structure of a 20 kDa superfluorinated gold nanocluster, Nature Communications (2022). DOI: 10.1038/s41467-022-29966-2
Journal information: Nature Communications
Source: Politecnico Milano