ИСТИНА

This work is focused on the development of sol-gel approaches to reusable titania-supported catalysts with potential interest for industrial productions of fine chemicals. The immobilization of air-stable metal complexes with nitrogen ligands such as 1,10- phenanthroline and porphyrin was investigated by reason of their remarkable catalytic and photocatalytic properties (Fig. 1).1-3 We explore different routes for immobilizing these complexes using titania as support and phosphonic acids as anchoring groups. This strategy combines several advantages including the strong covalent linkage of phosphonates to TiO2 networks and excellent mechanical, thermal and chemical properties of titania. In particular, we were interested to control the porosity of the materials and prepare cost-effective catalysts with surface characteristics that are relatively close to those of mesoporous materials commonly used as heterogenized catalysts such as functionalized ordered silicas. In this regard, the immobilization of phosphonate-substituted 1,10-phenanthroline ligands and their copper(I) complexes was investigated in detail. First, materials were prepared by reacting ligands or their complexes with titanium isopropoxide according to the sol-gel process (Routes C and D, Fig. 1). Alternatively, these ligands and complexes were grafted onto the surface of mesoporous titanium oxide (SBET = 650 m2 g–1) (Routes A and B, Fig. 1). Then immobilization of Ru(II) and Pd(II) complexes with 1,10-phenanthrolines and Zn(II), Mn(III) and In(III) porphyrins was carried out to prepare porous heterogenized catalysts. Finally, the catalytic performance of the most porous materials was examined in the Huisgen cycloaddition, Sonogashira-type reactions and the photocatalytic oxidation of sulfides by molecular oxygen.