DEFT polarization transfer in Si-29-NMR investigations of organically modified alkoxysilanes

The DEFT heteronuclear polarization transfer pulse sequence was used to unambiguously assign the high-resolution Si-29-NMR (nuclear magnetic resonance) for the hydrolyzed monomer species in trimethylmethoxysilane, dimethyldimethoxysilane and methyltrimethoxysilane. The response of the DEFT sequence as a function of the interpulse delay time tau and the variable pulse angle theta were analyzed for spin systems with multiple heteronuclear J-couplings. These results allow the DEFT sequence to be optimized for sensitivity enhancement in addition to providing an editing method for Si-29-NMR of organically modified alkoxysilanes. (C) 1997 Elsevier Science B.V.