The structure and binding mode of citrate in the stabilization of gold nanoparticles
Widdifield, Cory M.
Anjum, Dalaver H.
Hedhili, Mohamed N.
Kelly, Michael J.
El Eter, Mohamad
KAUST DepartmentKAUST Catalysis Center (KCC)
Physical Sciences and Engineering (PSE) Division
Imaging and Characterization Core Lab
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AbstractElucidating the binding mode of carboxylate-containing ligands to gold nanoparticles (AuNPs) is crucial to understand their stabilizing role. A detailed picture of the three-dimensional structure and coordination modes of citrate, acetate, succinate and glutarate to AuNPs is obtained by 13C and 23Na solid-state NMR in combination with computational modelling and electron microscopy. The binding between the carboxylates and the AuNP surface is found to occur in three different modes. These three modes are simultaneously present at low citrate to gold ratios, while a monocarboxylate monodentate (1κO1) mode is favoured at high citrate:gold ratios. The surface AuNP atoms are found to be predominantly in the zero oxidation state after citrate coordination, although trace amounts of Auδ+ are observed. 23Na NMR experiments show that Na+ ions are present near the gold surface, indicating that carboxylate binding occurs as a 2e− L-type interaction for each oxygen atom involved. This approach has broad potential to probe the binding of a variety of ligands to metal nanoparticles.
CitationAl-Johani H, Abou-Hamad E, Jedidi A, Widdifield CM, Viger-Gravel J, et al. (2017) The structure and binding mode of citrate in the stabilization of gold nanoparticles. Nature Chemistry 9: 890–895. Available: http://dx.doi.org/10.1038/nchem.2752.
SponsorsThis work received support from the King Abdullah University of Science and Technology (KAUST) and ERC Advanced Grant No. 320860. For computer time, this research used the resources of the Supercomputing Laboratory at King Abdullah University of Science & Technology (KAUST) in Thuwal, Saudi Arabia.