Long-lived Nuclear Hyperpolarization of Methyl Groups

甲基的长寿命核超极化

• 批准号: EP/N002482/1
• 负责人: Malcolm Levitt
• 金额: $ 90.28万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FN002482%2F1
• 关键词: Long; lived; Nuclear; Hyperpolarization; Methyl

Nuclear Magnetic Resonance (NMR) is a technique which uses the fact that the nuclei of many atoms act as tiny radiotransmitters, emitting radio signals at precisely-defined frequencies, which can be detected by a carefully-tuned detector. In an NMR experiment, the nuclei are first magnetised by placing a sample in a strong magnetic field for some time. A sequence of radiofrequency pulses is then applied to the sample, which subsequently emits radiowaves which are detected in the radio receiver. The pattern of emitted waves provides information on the chemical composition and spatial distribution of the sample.In ordinary circumstances, the NMR and MRI signals emitted by the nuclei are relatively weak, since the magnetic moments of the nuclei point in random directions. In 2003, a revolutionary method was developed for causing the nuclei to temporarily line up with each other, increasing the strength of NMR signals by a factor of ten thousand or even more. This method is called dissolution-DNP (where DNP stands for "dynamic nuclear polarization") and an instrument to implement this is built and marketed by the British company Oxford Instruments. However a drawback of the technique is that the greatly enhanced polarization (called hyperpolarization) dies out quickly. Our group showed in 2004 that for some substances the decay time could be extended by a factor of 10 or more by using special quantum states which are non-magnetic, called long-lived states.Last year evidence was presented that chemical groups called methyl groups (CH3) support long-lived states. These small symmetric groups are very common in chemistry and biology. A methyl group has the shape of a small propellor and usually rotates very rapidly with respect to the rest of the molecule. Our group showed that this propellor motion gives rise to a certain class of long-lived states. We used our theory to explain some prior results that had not been explained before, and performed a first series of experiments to validate the theory. In this project we will combine these developments to generate methyl long-lived states that are strongly hyperpolarized and give rise to greatly enhanced NMR signals. We propose methods for validating and exploiting these states in molecules containing methyl groups, which are very common in natural substances. The project involves an interdisciplinary combination of quantum mechanics, engineering, experimental spectroscopy, and chemical synthesis, all of which are essential for the success of the project. We will develop and demonstrate a range of new magnetic resonance methods with a wide range of applications in medicine, chemical engineering and materials science.

核磁共振（NMR）是一种利用许多原子的原子核作为微小无线电发射器的事实的技术，它以精确定义的频率发射无线电信号，这些信号可以被精心调谐的探测器探测到。在核磁共振实验中，首先将样品置于强磁场中一段时间，使原子核磁化。然后将一系列射频脉冲施加到样品上，样品随后发出在无线电接收器中检测到的无线电波。发射波的模式提供了样品的化学成分和空间分布的信息。在一般情况下，原子核发出的核磁共振和核磁共振信号相对较弱，因为原子核的磁矩指向随机方向。2003年，人们发明了一种革命性的方法，可以使原子核暂时排列在一起，从而将核磁共振信号的强度提高一万倍甚至更多。这种方法被称为溶解-DNP （DNP代表“动态核极化”），实现这种方法的仪器是由英国牛津仪器公司制造和销售的。然而，该技术的一个缺点是大大增强的极化（称为超极化）很快就会消失。我们的研究小组在2004年表明，通过使用特殊的非磁性量子态，即所谓的长寿命态，某些物质的衰变时间可以延长10倍或更多。去年有证据表明甲基（CH3）支持长寿命状态。这些小的对称群在化学和生物学中很常见。甲基有一个小螺旋桨的形状，通常相对于分子的其余部分旋转得非常快。我们的研究小组表明，这种推动运动产生了某种长期存在的状态。我们用我们的理论解释了一些之前没有解释过的结果，并进行了一系列的实验来验证这个理论。在这个项目中，我们将结合这些发展来产生甲基长寿命状态，这些状态是强超极化的，并大大增强了核磁共振信号。我们提出的方法来验证和利用这些状态的分子含有甲基，这是非常常见的天然物质。该项目涉及量子力学、工程学、实验光谱学和化学合成的跨学科结合，所有这些都是项目成功的关键。我们将开发和展示一系列新的磁共振方法，这些方法在医学、化学工程和材料科学方面有着广泛的应用。

项目成果

Hyperpolarized long-lived nuclear spin states in monodeuterated methyl groups.

• DOI: 10.1039/c8cp00253c
• 发表时间: 2018-04-18
• 期刊: Physical chemistry chemical physics : PCCP
• 作者: Elliott SJ ;Meier B ;Vuichoud B ;Stevanato G ;Brown LJ ;Alonso-Valdesueiro J ;Emsley L ;Jannin S ;Levitt MH
• 通讯作者: Levitt MH

Experimental evidence for the role of paramagnetic oxygen concentration on the decay of long-lived nuclear spin order.

• DOI: 10.1039/c9ra03748a
• 发表时间: 2019-07-23
• 期刊: RSC advances
• 影响因子: 3.9