Synthesis and characterisation of a Ru-II([14]aneS(4)) complex immobilisedin MCM-41-type mesoporous silica

Ruthenium(ii) complexes containing the macrocycle 1,4,8,11-tetrathiacyclote tradecane ([14]aneS(4)) and nitrogen-coordinated nitrile ligands were prepa red using cis-[Ru(DMSO)(4)Cl-2] as the starting material. The first synthet ic step consisted of introduction of the thioether ligand to give [Ru([14]a neS(4))(DMSO)Cl]Cl. Substitution of the DMSO ligand by the nitrile ligands NCCH3 or NC(CH2)(3)Si(OEt)(3) (L) gave the complexes [Ru([14]aneS(4))(L)Cl] X (X=Cl-, PF6-). Introduction of the triethoxysilyl ligand allowed the [Ru( [14]aneS(4))Cl](+) fragment to be tethered to the surface of the ordered me soporous silica MCM-41 by pore volume impregnation of a solution of the com plex in dichloromethane. A high metal loading was achieved (0.56 mmol g(-1) ). Powder XRD and N-2 adsorption studies of the derivatised material indica ted that the textural properties of the support were preserved during the g rafting experiment and that the channels remained accessible, despite a lar ge reduction in both surface area and pore volume (ca. 50%). IR, UV/VIS, ph otoluminescence and MAS NMR spectroscopy (C-13, Si-29) confirmed that the s tructural integrity of the Ru-II complex was retained during immobilisation , except for loss of ethoxide groups due to the reaction with pendant silan ols on the silica surface.