Nanoporous MCM-41 materials modified with Copper(I)-salen type complex: as efficient and reusable catalyst for the synthesis of 1,2,3-triazoles

Abstract

The development of new mesoporous organic–inorganic hybrid materials, as an example of heterogeneous catalysts, has played a key role in eco-friendly industrial processes.[1, 2] Immobilization of metal organic complexes on solid supports is highly desirable due to the facilitation both the isolation and recycling of the catalyst by simple filtration. Moreover, these catalysts exhibit a significant improvement in activity, selectivity and stability, which are attributed to contributions of isolated sites on the solid surface.[3-5] The immobilization of copper complexes by covalent anchoring of the ligand on the surface of mesoporous MCM-41 has been described. Bis[2-(phenylthio)benzylidene]-1,2-ethylenediamine as a new N2S2-donor salen-type ligand was covalently anchored onto nanopores of MCM-41 followed coordinated with copper (I) halide. The organic-inorganic hybrid material was achieved readily using 3-mercaptopropyltrimethoxysilane as a reactive surface modifier. 2-nitrobenzaldehyde was reacted smoothly with the thiol moieties in order to form functionalized nanoporous silica with carbaldehyde groups. The resulting supported organic moieties were converted to thiosalen ligand and coordinated with CuX (X=CN, Cl, Br, I). The heterogenized catalyst was evaluated by the condensation reaction of benzylhalides, sodium azide and terminal alkynes. In this reaction, the corresponding triazoles were obtained as single products in good to excellent yields (scheme 1).