Titanium Oxo-Clusters: Vesatile Nano-Objects for the Design of Hybrid Compounds
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1007-S15-02
Titanium Oxo-Clusters: VVesatile Nano-Objects for the Design of Hybrid Compounds Laurence Rozes1, Sébastien Cochet2, Théo Frot1, Giulia Fornasieri3, Capucine Sassoye1, Michael Popall2, and Clément Sanchez1 1 Laboratoire Chimie de la Matière Condensée de Paris, UPMC, Univ Paris 06, UMR 7574, 4 place Jussieu, Paris, 75252 cedex 05, France 2 Fraunhofer Institut fuer Silicatforschung, Wuersburg, 97082, Germany 3 Laboratoire de Chimie Inorganique, Université Paris Sud 11, Orsay, 91405, France ABSTRACT The description of three titanium oxo-clusters and their use as inorganic components of hybrid organic-inorganic materials are reported. The first approach consists to add titanium oxoclusters, [Ti6O4(C6H5COO)8(OPrn)8], in an ORMOCER® based hybrid medium. Nano-sized titanium oxo-clusters combined with the chemical nature of the components, allow the tuning of the optical properties, especially the refractive index. The second approach consists to associate functionalized titanium oxo-clusters to elaborate hybrid materials with perfectly defined inorganic domains. The more relevant example of titanium oxo-cluster to build hybrid networks from nano-building blocks is the oxo-cluster [Ti16O16(OEt)32]. Indeed, the nature and the number of functional groups at the surface of these metallic oxo-clusters can be tuned in order to generate cross-linking agents of organic polymers. The studies of the structure-property relationships of the resulting nanocomposites have been investigated. Finally the structure of a purely carboxylate oxo-clusters is briefly described. This new family of stable oxo-clusters opens the way for the production of original hybrid compounds.
INTRODUCTION The titanium oxo-clusters [TixOy(OR)z(CL)w] are polynuclear titanium complexes whose size is between 5 and 25 Å. Their perfectly defined structures were characterized by single crystal X-ray diffraction. The titanium oxo-clusters exhibit a rich variety in structural types characterized by different coordination modes of the ligands (O, OR, and CL), diversity in linkages of the coordination polyhedra, degree of condensation O/Ti, and coordination number of Ti atoms. Their nuclearity (number of titanium atoms) reported in literature varies from two to eighteen. The metallic centers that exhibit coordination numbers between four and six are coordinated to bridging oxo-ligands and terminal or bridging alkoxy OR groups. A large variety of oxo bridges can be present in the clusters from µ2-O to µ5-O. Furthermore, numerous titanium oxo-clusters bear strongly complexing oxo-ligands CL (β-diketone, carboxylic acid, phosphonates…) on their surfaces with a chelating or a bridging coordination mode [1]. To summarize, titanium oxo-clusters can be described as nano-sized hybrid species formed by a well defined inorganic core surrounded by an organic shell. These nano-objects can be used as additives to modify the properties of materials, or can participate to the elaboration of nanocomposites when they bear reactive ligands [2-7]. The incorporation of titani
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