Heteronuclear dipolar decoupling in liquid‐crystal NMR using supercycled SWf‐TPPM sequences

Heteronuclear dipolar decoupling is an essential requirement for extracting structural information from the ¹³C NMR spectra of liquid crystals. Efficient schemes for heteronuclear dipolar decoupling in such systems are formulated here by supercycling SW_f‐TPPM, a sequence introduced recently for this purpose in rotating solids. These sequences are compared with two other commonly used decoupling schemes in liquid‐crystal NMR, SPINAL‐64 and SW_f‐TPPM, by analyzing the intensities of various resonances in the proton decoupled ¹³C spectrum of the liquid‐crystal 4‐n‐pentyl‐4′‐cyanobiphenyl (5CB). The effectiveness of the decoupling programs with respect to experimental parameters such as RF field strength, decoupler offset frequency and phase angle is also presented. Copyright © 2010 John Wiley & Sons, Ltd.