Yanan Li (New York University, United States)
LinkedIn: @Yanan Li; X: @YananLi12451
Abstract: Multiple-quantum NMR spectroscopy has long been employed to selectively isolate specific magnetization components. Here, we combined CRAZED and triple-quantum-filtered (TQF) experiments to investigate multiple quantum coherences in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4). This approach offers detailed insights into the ion dynamics and intermolecular interactions characteristic of ionic liquids.
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Hi, on slide 5, you show the dependence of the signal intensity on the angle θ. Which experimental parameters set up this angle? Another question: how many coupled spins are necessary to have to expect triple quantum coherence? And zero order coherence?
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For the first question,we control the angle θ by adjusting the relative amplitudes of gradients along y and z (Gz, Gy).
For the second question, triple quantum coherence are required at least three coupled spins (like I1+I2+I3+ or I1-I2-I3-). Zero order coherences are formed with at least 2 spins (like I1+I2- or I1-I2+).
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Yanan,
Thank you for your presentation. You clearly demonstrated intermolecular contributions to the quantum coherence. Since this is an ionic compound, does the contribution come from the cationic counterpart of BF₄ anion or from other ionic liquid species? Do you expect certain nuclei to contribute more significantly? Looking forward to your insights. -
Thank you for the good question! I would say that the observed intermolecular quantum coherences of 11B likely originate from interactions between the BF4 anion and both neighboring anions and cations (11B-1H, 11B -19F, 11B-11B). It is difficult to draw a conclusion from the standard CRAZED experiments, but I tend to favor 1H due to its higher magnetic separation ratio and natural abundance.
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