Torodii Daria, Holmes Jacob B, Grohe Kristof, de Oliveira-Silva Rodrigo, Wegner Sebastian, Sakellariou Dimitrios, Emsley Lyndon
Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
Bruker BioSpin GmbH & Co KG, 76275, Ettlingen, Germany.
Nat Commun. 2024 Dec 30;15(1):10799. doi: 10.1038/s41467-024-55126-9.
While H-H J-couplings are the cornerstone of all spectral assignment methods in solution-state NMR, they are yet to be observed in solids. Here we observe H-H J-couplings in plastic crystals of (1S)-(-)-camphor in solid-state NMR at magic angle spinning (MAS) rates of 100 kHz and above. This is enabled in this special case because the intrinsic coherence lifetimes at fast MAS rates become longer than the inverse of the H-H J couplings. For example, at 160 kHz MAS the coherence lifetimes are longer than 20 ms, corresponding to refocused linewidths of less than 15 Hz. As a result, we are able to record two-dimensional H-H J resolved spectra that allow the observation and measurement of H-H J-couplings in solid camphor. The J-couplings also lead to unambiguous through-bond correlations in H-H refocused incredible natural abundance double quantum transfer (INADEQUATE) and uniform-sign cross-peak double-quantum-filtered correlation spectroscopy (UC2QFCOSY) experiments.
虽然H-H J耦合是溶液态核磁共振中所有光谱归属方法的基石，但在固体中尚未观察到。在此，我们在固态核磁共振中，以100kHz及以上的魔角旋转（MAS）速率，在(1S)-(-)-樟脑的塑性晶体中观察到了H-H J耦合。在这种特殊情况下能够实现这一点，是因为快速MAS速率下的本征相干寿命变得比H-H J耦合的倒数更长。例如，在160kHz MAS时，相干寿命超过20ms，对应于小于15Hz的重聚焦线宽。因此，我们能够记录二维H-H J分辨光谱，从而实现对固体樟脑中H-H J耦合的观察和测量。这些J耦合还在H-H重聚焦的不可思议的自然丰度双量子转移（INADEQUATE）和均匀符号交叉峰双量子滤波相关光谱（UC2QFCOSY）实验中产生明确的通过键的相关性。
