Amino Acid-Based Stabilization of Oxide Nanocrystals in Polar Media : From Insight in Ligand Exchange to Solution ¹H NMR Probing of Short-Chained Adsorbates

Ligand exchange is a crucial step between nanocrystal synthesis and nanocrystal application. Although colloidal stability and ligand exchange in nonpolar media are readily established, the exchange of native, hydrophobic ligands with polar ligands is less systematic. In this paper, we present a vers...

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Veröffentlicht in:Langmuir : the ACS journal of surfaces and colloids. - 1992. - 32(2016), 8 vom: 01. März, Seite 1962-70
1. Verfasser: De Roo, Jonathan (VerfasserIn)
Weitere Verfasser: Coucke, Sofie, Rijckaert, Hannes, De Keukeleere, Katrien, Sinnaeve, Davy, Hens, Zeger, Martins, José C, Van Driessche, Isabel
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2016
Zugriff auf das übergeordnete Werk:Langmuir : the ACS journal of surfaces and colloids
Schlagworte:Journal Article Research Support, Non-U.S. Gov't
Beschreibung
Zusammenfassung:Ligand exchange is a crucial step between nanocrystal synthesis and nanocrystal application. Although colloidal stability and ligand exchange in nonpolar media are readily established, the exchange of native, hydrophobic ligands with polar ligands is less systematic. In this paper, we present a versatile ligand exchange strategy for the phase transfer of carboxylic acid capped HfO2 and ZrO2 nanocrystals to various polar solvents, based on small amino acids as the incoming ligand. To gain insight in the fundamental mechanism of the exchange, we study this system with a combination of FTIR, zeta potential measurements, and solution (1)H NMR techniques. The detection of surface-associated, small ligands with solution NMR proves challenging in this respect. Tightly bound amino acids are undetectable, but their existence can be proven through displacement with other ligands in titration experiments. Alternatively, we find that methyl moieties belonging to bound species can circumvent these limitations because of their more favorable relaxation properties as a result of internal mobility. As such, our results are not limited to amino acids but to any short-chained ligand and will therefore facilitate the rigorous investigation and understanding of various ligand exchange processes
Beschreibung:Date Completed 29.06.2016
Date Revised 01.03.2016
published: Print-Electronic
Citation Status PubMed-not-MEDLINE
ISSN:1520-5827
DOI:10.1021/acs.langmuir.5b04611