/sup 13/C CP/MAS NMR study of molecular motion in n-alkylsilanes bonded to the silica surface

Journal Article · Wed Apr 06 04:00:00 EST 1983 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00345a028· OSTI ID:5684669

Sindorf, D W; Maciel, G E

Motional dynamics in long-chain aliphatic phases bonded to silica gel were studied using CP/MAS /sup 13/C relaxation measurements. Differences in cross-polarization rates and proton T/sub 1p/ and T/sub 1/ values observed for samples prepared by silylation of silica gel with dimethyloctadecylchlorosilane (DMODCS) and dimethyloctylchlorosilane (DMOCS) identified methyl group rotation as a likely principal source of proton spin-lattice relaxation. Cross-polarization rates for carbons located at equidistant positions from the surface-attached silicon atom were similar for DMODCS and DMOCS systems. In general, cross-polarization efficiency was observed to decrease with increasing distance from the surface along the alkyl chain. However, for distances greater than roughly eight carbon units cross-polarization rates are essentially the same.

• Research Organization: Colorado State Univ., Fort Collins
• OSTI ID: 5684669
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 105:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKYL RADICALS
CHALCOGENIDES
CHEMICAL BONDS
HYDRIDES
HYDROGEN COMPOUNDS
MAGNETIC RESONANCE
MINERALS
NUCLEAR MAGNETIC RESONANCE
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADICALS
RELAXATION
RESONANCE
SILANES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPIN-LATTICE RELAXATION