Hung Ivan, Gan Zhehong
National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.
J Phys Chem Lett. 2020 Jun 18;11(12):4734-4740. doi: 10.1021/acs.jpclett.0c01236. Epub 2020 Jun 3.
Indirect NMR detection via protons under fast magic-angle spinning can help overcome the low sensitivity and resolution of low-γ quadrupole nuclei such as Cl. A robust and efficient method is presented for indirectly acquiring the double-quantum satellite-transition (DQ-ST) spectra of quadrupole nuclei. For a spin = 3/2, the DQ-STs have a much smaller second-order quadrupolar broadening, one-ninth compared to that of the central transition. Thus, they can provide a factor of up to 18 in resolution enhancement. The indirect detection of DQ-STs via protons is carried out using the heteronuclear multiple-quantum coherence (HMQC) experiment with the transfer of populations in double-resonance (TRAPDOR) recoupling mechanism. The resolution enhancement by detecting DQ-STs and the high efficiency of the TRAPDOR-HMQC experiment are demonstrated by Cl NMR of several active pharmaceutical ingredients (APIs).
在快速魔角旋转下通过质子进行间接核磁共振检测有助于克服诸如氯等低γ四极核的低灵敏度和分辨率问题。本文提出了一种稳健且高效的方法，用于间接获取四极核的双量子卫星跃迁（DQ-ST）光谱。对于自旋I = 3/2的核，DQ-ST具有小得多的二阶四极展宽，仅为中心跃迁展宽的九分之一。因此，它们可将分辨率提高多达18倍。通过质子间接检测DQ-ST是利用异核多量子相干（HMQC）实验，并结合双共振（TRAPDOR）再耦合机制中的布居转移来实现的。通过几种活性药物成分（API）的氯核磁共振证明了检测DQ-ST带来的分辨率提高以及TRAPDOR-HMQC实验的高效性。
