SYNTHESIS AND SOLID-STATE NMR STRUCTURAL CHARACTERIZATION OF POLYSILOXANE-IMMOBILIZED THIOL AND THIOL-AMINE LIGANDS

Thiol and thiol-amine ligand systems that are immobilized in a polysil oxane matrix have been synthesized via the sol-gel process by hydrolyt ic condensation of mixtures of Si(OEt)(4) and (MeO)(3)Si(CH2)(3)SH, as well as (EtO)(3)Si(CH2)(3)NH2 or (MeO)(3)Si(CH2)(3)NH(CH2)(2)NH2 for thiol-amine systems. In these systems, most of the amine groups can be protonated by aqueous acid solution. Solid-state Si-29 nuclear magnet ic resonance (NMR) spectra confirm the fact that these materials, in a nalogy to polysiloxane-immobilized amine systems, undergo leaching of small oligomers containing ligand groups when they are treated with aq ueous acid. N-15 NMR spectra indicate that the amine groups in these s ystems may be involved in hydrogen bonding with silanols or with other ligand groups. C-13-detected and Si-29 detected T-1(H) values were me asured on the polysiloxane-immobilized thiol system, thiol-monoamine s ystem and thiol-diamine system. The T-1(H) results suggest that the li gand groups in these systems are evenly distributed in the polysiloxan e networks.