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

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.

Quantum confinement effects on the surface enhanced Raman spectra of hybrid systems molecule‐TiO2 nanoparticles

“…While similar observations were made in the course of earlier theoretical investigations of TiO 2 -dopamine clusters [32][33][34][35][36], it also leads to an enhanced bandgap of the TiO 2 cluster as compared to the experimentally determined bandgaps of the TiO 2 nanoparticles {anatase (3.21 eV), rutile (3.00 eV), and brookite (3.13 eV)} [37].…”

Probing the activities of UV and visible-light absorbing photocatalyst powders using a resazurin-based photocatalyst activity indicator ink (Rz Paii )

“…catecholate-type ligands [15], phenols [16,17] and aromatic carboxylic acids [17], as the 'test pollutant'.…”

Synthesis and characterization of the surface modified titanium dioxide/epoxy nanocomposites

“…Organic groups that can be used to attach ligands to the titanium dioxide surface are amine [19], ammonium [20] and different benzene derivatives, mostly catechol and salicylic acid [21][22][23]. Aromatic ligands with two or three adjacent phenolic OH groups (catechol, pyrogallol and gallic acid) can be adsorbed on the surface of TiO 2 by forming chelating or bridging complexes with titanium ions on the surface [24][25]. In our previous works, TiO 2 nanoparticles were surface modified with different alkyl gallates [26] and then incorporated into the poly(methyl mehacrylate) and epoxy matrix [27].…”