Mesoporous organosilicas with Pd(II) complexes in their framework

Incorporation of various Pd(II) complexes into the framework of mesoporous organosilica materials has been achieved by co-condensation, using a facile solvent-free one-pot method. The synthesis of Pd(II) complexes using ligands with triethoxysilyl terminal groups allowed for their homogeneous in situ incorporation into the organosiliceous structure. Organic/inorganic precursor bis(triethoxysilyl)ethane was used both, as silica source and as solvent for the synthesis of the complexes, avoiding the use of any other organic co-solvent and making the synthesis more environmentally friendly. The mild synthetic conditions used such as neutral pH, room temperature and ethanol extraction of the surfactant, allowed for a cleaner route for the preparation of hybrid organic/inorganic mesoporous materials with Pd(II) complexes covalently bounded to the support. The chemical integrity of the metal complexes after the synthesis of the hybrid material, [trans-PdCl2L2] (L = 4-C5H4N-(CH2)(2)Si(OEt3) and PPh2(CH2)(2)Si(OEt)(3)), was confirmed by several spectroscopic techniques. A systematic study of the role of the different parameters involved in the synthesis of these materials and their relation with the final morphology of the catalysts is herein described. (C) 2012 Elsevier Inc. All rights reserved.