Diffusion ordered NMR measurements on nanoclusters and nanoparticles in the frame of a postdoctoral stay of Dr. Virginie ESCAX, Université Pierre et Marie Curie, Paris, France

Project Details

Description

One of the goals of project G.0016.02 of the FWO is to develop novel applications of DOSY (diffusion ordered spectroscopy) NMR in inorganic chemistry and material sciences, with the aim of developing new tools enabling one to investigate the mechanisms of interactions between organic ligands and nanoclusters or -particles. Insight into these mechanisms are expected to enable one in turn to develop novel methods of preparation of size-tailored metal oxide particles under highly suitable soft sol-gel chemistry conditions. Because the interactions with anions and nucleophiles at the nano-particle surface are usually observed on a very fast NMR-time scale (averaged signals), in systems hardly prone to low temperature measurements, it is aimed at obtaining information via diffusion resolved resonances from DOSY spectra. Such spectra should, at least qualitatively and in favourable conditions even quantitatively, allow to find out to which extent anions or nucleophiles are bound to metal atoms of the tin oxide particles (free, bound or in equilibrium free/bound; slow or fast on the NMR and/or diffusion time scale).
In collaboration with Prof. C. Sanchez and Dr. F. Ribot, Laboratoire de Chimie de la Matière Condensée, likewise at the Université Pierre et Marie curie, such a strategy is presently being worked out for the organotin {(BuSn)12O14(OH)6}2+ nanoclusters and SnO2 nano-particles covered with nucleophiles such as alcohols, chelating ligands (acetyl- and benzoylacetonates, fluorinated or not, etc.), inorganic (fluoride, etc.) and organic anions (paratoluene sulfonate, phosphinates, phosphonates, carboxylates, etc.). The purpose here is to trace the nature of the interactions (thermodynamically/kinetically determined, in static or dynamic equilibrium, weak or strong interactions; electrostatic or covalent; 'random' or regioselectively distributed) such particles are involved in upon addition of organic anions and/or nucleophiles to solutions or sols of such structural units. Only by a systematic approach, the physico-chemical and structural factors determining the stability of such nano-particles and modulating their growth to cross-linked oxides, can be defined. The most important challenge is to investigate whether association constants can be determined via DOSY-measurements for different ligands on the same nano-particle. To the best of our knowledge, this largely represents unexplored scientific area. Extending such studies to the Ti18O22(OBu)26(acac)2 cluster and TiO2 nano-particles should allow to assess the universality of this strategy, given that titanium structures are known for their substantial stronger interactions with nucleophiles than their tin counterparts.
AcronymFWOSL14
StatusFinished
Effective start/end date6/01/0331/12/03

Flemish discipline codes

  • Physical sciences
  • Chemical sciences

Keywords

  • Metaloxide clusters
  • Metal oxide clusters
  • Chelating ligands
  • Diffusiemetingen
  • Metaaloxide clusters
  • Tinoxide
  • Chelaterende liganden
  • Titanium oxide
  • Ligand interactions on nanoparticles
  • DOSY-NMR
  • Tin oxide
  • Titaanoxide
  • Diffusion measurements
  • NMR Spectroscopy