Stabilization of Colloidal Ti, Zr, and Hf Oxide Nanocrystals
by Protonated Tri‑n‑octylphosphine
Oxide (TOPO) and Its Decomposition Products
Posted on 2017-11-17 - 20:13
Although
TiO2, ZrO2, and HfO2 nanocrystals
are often synthesized in tri-n-octylphosphine oxide
(TOPO), it is unclear whether TOPO also serves as ligand. Using liquid
and solid state 1H and 31P nuclear magnetic
resonance spectroscopy and X-ray fluorescence spectroscopy, we show
that the nanocrystal surface is capped by several derivatives of TOPO.
In the 31P NMR spectrum, di-n-octylphosphinate
(δ = 57 ppm) and P,P′-(di-n-octyl) pyrophosphonate (δ = 20 ppm) are found coordinated
to the nanocrystal. In addition, hydrogen chloride associates with
the metal oxide nanocrystal surface and protonates TOPO. The resulting
hydroxyl-tri-n-octylphosphonium, [HO-PR3]+, is tightly associated with the nanocrystal surface
(δ(31P) = 73 ppm) due to electrostatic interactions
and hydrogen bonding. To simplify the complex surface composition,
we exchange the original surface species for carboxylate or phosphonate
ligands. The protonation of TOPO is an unexpected example of lyophilic
ion pairing between an acidic metal oxide nanocrystal and a weakly
basic ligand molecule that is formed in nonpolar solution. Our results
contrast with the classically envisaged L-type binding motif of TOPO
to surface metal ions. The generality of this stabilization mode and
its relevance to catalysis is discussed.
CITE THIS COLLECTION
DataCite
3 Biotech
3D Printing in Medicine
3D Research
3D-Printed Materials and Systems
4OR
AAPG Bulletin
AAPS Open
AAPS PharmSciTech
Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)
Academic Medicine
Academic Pediatrics
Academic Psychiatry
Academic Questions
Academy of Management Discoveries
Academy of Management Journal
Academy of Management Learning and Education
Academy of Management Perspectives
Academy of Management Proceedings
Academy of Management Review
Keukeleere, Katrien De; Coucke, Sofie; De Canck, Els; Van Der Voort, Pascal; Delpech, Fabien; Coppel, Yannick; et al. (2017). Stabilization of Colloidal Ti, Zr, and Hf Oxide Nanocrystals
by Protonated Tri‑n‑octylphosphine
Oxide (TOPO) and Its Decomposition Products. ACS Publications. Collection. https://doi.org/10.1021/acs.chemmater.7b04580
or
Select your citation style and then place your mouse over the citation text to select it.
SHARE
Usage metrics
AUTHORS (10)
KK
Katrien De Keukeleere
SC
Sofie Coucke
ED
Els De Canck
PV
Pascal Van Der Voort
FD
Fabien Delpech
YC
Yannick Coppel
ZH
Zeger Hens
ID
Isabel Van Driessche
JO
Jonathan S. Owen
JR
Jonathan De Roo
KEYWORDS
X-ray fluorescence spectroscopysurface metal ionsoctylphosphine oxideHf Oxide Nanocrystalsnonpolar solutionnanocrystal surfacehydrogen chloride associatesL-type binding motifacidic metal oxide nanocrystalDecomposition Productsligand moleculeHfO 2 nanocrystalsstate 1 Hresults contrastlyophilic ion pairingresonance spectroscopystabilization modesurface compositionprotonates TOPOmetal oxide nanocrystal surfaceColloidal Tisurface species73 ppmZrO 2TiO 231 PHO-PR 3phosphonate ligands20 ppm31 P NMR spectrum57 ppm