Disclosing Interfaces of ZnO Nanocrystals Using Dynamic Nuclear Polarization: Sol‐Gel versus Organometallic Approach
Résumé
The unambiguous characterization of the coordination chemistry of nanocrystal surfaces that have been produced by a wetchemical synthesis presently remains a highly challenging issue. Here, zinc oxide nanocrystals (ZnO NCs) coated by monoanionic diphenyl phosphate (DPP) ligands were derived by a traditional sol-gel process and a one-pot self-supporting organometallic (OSSOM) procedure, and advanced atomic-scale characterization through dynamic nuclear polarization (DNP-)enhanced solid-state nuclear magnetic resonance (ssNMR) spectroscopy has notably enabled resolving their vastly different surface-ligand interfaces. For the OSSOM-derived NCs, DPP moieties form stable and strongly-anchored µ2-and µ3-bridgingligand pairs that are resistant to competitive ligand exchange processes. Contrastingly, the sol-gel-derived NCs contain a wide variety of coordination modes of DPP ligands and a ligand exchange process takes place between DPP ligands and glycerol molecules. This highlights the power of DNP-enhanced ssNMR for detailed NC surface analysis and the superiority of the OSSOM approach for the preparation of high quality ZnO NCs.
Domaines
Chimie
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