Measurement of Interfluorine Distances in Solids

✍ Scribed by M. Lane Gilchrist Jr.; Kenji Monde; York Tomita; Takashi Iwashita; Koji Nakanishi; Ann E. McDermott

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 170 KB
• Volume: 152
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.2001.2351

✦ Synopsis

19 F homonuclear dipolar recoupling methods were used to measure internuclear distances ranging from 5 to 12 Å in fluorinated organic compounds in the solid state. Magic-angle-spinning-based high-resolution techniques were utilized. Trifluoromethyl and aromatic fluorine groups were seperated by rigid aromatic spacers; these compounds were diluted into nonfluorinated host molecule matrices to give isolated homonuclear spin pairs with known internuclear distances. Radiofrequency-driven recoupling (RFDR) was used to elicit magnetization exchange between the spin pairs in 1D and 2D experiments. Simulation of the exchange was accomplished using a Monte Carlo-type algorithm to search the parameter space. These methods allow the determination of distances with an accuracy of 1 Å at shorter distances and 2 Å at longer distances, with the assumption of no prior knowledge of T ZQ 2 .