Spectral Editing in 13C MAS NMR under Moderately Fast Spinning Conditions

✍ Scribed by Enrico De Vita; Lucio Frydman

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 437 KB
• Volume: 148
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.2000.2255

✦ Synopsis

Novel procedures for the spectral assignment of peaks in highresolution solid-state 13 C NMR are discussed and demonstrated. These methods are based on the observation that at moderate and already widely available rates of magic-angle spinning (10 -14 kHz MAS), CH and CH 2 moieties behave to a large extent as if they were effectively isolated from the surrounding proton reservoir. Dipolarbased analogs of editing techniques that are commonly used in liquidstate NMR such as APT and INEPT can then be derived, while avoiding the need for periods of homonuclear 1 H-1 H multipulse decoupling. The resulting experiments end up being very simple, essentially tuning-free, and capable of establishing unambiguous distinctions among CH, CH 2 , and -C ͦ ͦ -/-CH 3 carbon sites. The principles underlying such sequences were explored using both numerical calculations and experimental measurements, and once validated their editing applications were illustrated on a number of compounds.