Open Access Nano Express

New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

Ivana A Janković1*, Zoran V Šaponjić1, Enis S Džunuzović2 and Jovan M Nedeljković1

Author Affiliations

1 Laboratory for Radiation Chemistry and Physics, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001, Belgrade, Serbia

2 Faculty of Technology and Metallurgy, Department of Physical Chemistry and Electrochemistry, University of Belgrade, Karnegijeva 4, 11120, Belgrade, Serbia

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Nanoscale Research Letters 2009, 5:81-88  doi:10.1007/s11671-009-9447-y

Published: 13 October 2009

Abstract

Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M−1 have been determined.

Keywords:
TiO2 nanoparticles; Surface modification; Catechol; Pyrogallol; Gallic acid