Characterization of Titanium Dioxide Nanoparticles Dispersed in Organic Ligand Solutions by Using a Diffusion‐Ordered Spectroscopy‐Based Strategy

Abstract

Diffusion‐ordered NMR spectroscopy (DOSY NMR) is presented as a tool for the determination of the diffusion coefficients of organic ligands in suspensions of titanium dioxide nanoparticles. The nanoparticles were prepared by a sol‐gel process by hydrolysis and condensation reactions of titanium tetra‐n‐butoxide in the presence of pentane‐2,4‐dione (acacH: acetylacetone), as well as para‐toluenesulfonic acid (pTsA) and n‐butanol (nBuOH). NMR spectroscopic studies were performed in various deuterated solvents, on both dispersed xerosols and diluted sols. The bipolar‐pulsed field gradient longitudinal eddy‐current delay (LED) pulse sequence was used for data acquisition. The data were processed by inverse Laplace transformation (ILT), by using a maximum entropy algorithm, to afford 2D DOSY spectra. Different diffusion regimes for organic ligands in the bound and unbound states were successfully discriminated, more particularly in [D₃]acetonitrile, thus allowing assessment of their interactions with the nanoparticles.