Synthesis and Characterization of Tris(mercaptomethyl)(2,4,6-trimethoxyphenyl)silane and Its Use for the Immobilization of the Si(CH₂SH)₃ Group on Silica via an Si−O−Si Linkage

Abstract

The tris(mercaptomethyl)silane RSi(CH2SH)3 (2; R = 2,4,6-trimethoxyphenyl) was synthesized, starting from the corresponding tris(chloromethyl)silane RSi(CH2Cl)3 (1). Compound 2 was characterized by elemental analysis, NMR studies (1H, 13C, 29Si), and single-crystal X-ray diffraction. The title compound was used as a silylation reagent for the immobilization of the Si(CH2SH)3 group on silica surfaces via an Si−O−Si linkage. Furthermore, an Si(CH2SH)3-containing silica material was synthesized that contains additional Si(CH2SH)2 units that are covalently linked by two Si−O−Si bridges. The silylated silica materials (characterized by solid-state 29Si and 13C NMR spectroscopy) are of interest for the immobilization of transition metals on silica surfaces via the Si(CH2SH)3 and Si(CH2SH)2 chelate ligands. This was demonstrated exemplarily by the Zn2+ uptake from aqueous zinc(II) sulfate solutions.