Decoherence optimized tilted-angle cross polarization: A novel concept for sensitivity-enhanced solid-state NMR using ultra-fast magic angle spinning

• Published in: Journal of magnetic resonance (1997) 2021-01, Vol.322, p.106857-106857, Article 106857
• Main Authors: Matsunaga, Tatsuya, Matsuda, Isamu, Yamazaki, Toshio, Ishii, Yoshitaka
• Format: Article
• Language: English
• Subjects: 1H-detected solid-state NMR; Biomolecular NMR; Multi-dimensional solid-state NMR; Solid state NMR; Ultra-fast MAS
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2020.106857

[Display omitted] •New cross polarization (CP) scheme in ultrafast magic-angle spinning (UFMAS).•It uses radio-frequency (RF) irradiation with frequency offset on 1H.•It can be combined with other CP schemes to enhance sensitivity by 1.2–1.4 times.•It realizes CP more selectively and with lower RF power in UFMAS. Ultra-fast magic-angle spinning (UFMAS) at a MAS rate (ωR/2π) of 60 kHz or higher has dramatically improved the resolution and sensitivity of solid-state NMR (SSNMR). However, limited polarization transfer efficiency using cross-polarization (CP) between 1H and rare spins such as 13C still restricts the sensitivity and multi-dimensional applications of SSNMR using UFMAS. We propose a novel approach, which we call decoherence-optimized tilted-angle CP (DOTA CP), to improve CP efficiency with prolonged lifetime of 1H coherence in the spin-locked condition and efficient band-selective polarization transfer by incorporating off-resonance irradiation to 1H spins. 13C CP-MAS at ωR/2π of 70–90 kHz suggested that DOTA CP notably outperformed traditional adiabatic CP, a de-facto-standard CP scheme over the past decade, in sensitivity for the aliphatic-region spectra of 13C-labeled GB1 protein and N-formyl-Met-Leu-Phe samples by up to 1.4- and 1.2-fold, respectively. 1H-detected 2D 1H/13C SSNMR for the GB1 sample indicated the effectiveness of this approach in various multidimensional applications.