Department of Chemistry, New York University, 100 Washington Sq. East, New York, NY 10003 (USA) http://www.nyu.edu/projects/jerschow/ http://www.nyu.edu/pages/canary/home.html.
Angew Chem Int Ed Engl. 2014 Mar 24;53(13):3396-9. doi: 10.1002/anie.201310284. Epub 2014 Mar 12.
Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) have become important techniques in many research areas. One major limitation is the relatively low sensitivity of these methods, which recently has been addressed by hyperpolarization. However, once hyperpolarization is imparted on a molecule, the magnetization typically decays within relatively short times. Singlet states are well isolated from the environment, such that they acquire long lifetimes. We describe herein a model reaction for read-out of a hyperpolarized long-lived state in dimethyl maleate using thiol conjugate addition. This type of reaction could lend itself to monitoring oxidative stress or hypoxia by sensitive detection of thiols. Similar reactions could be used in biosensors or assays that exploit molecular switching. Singlet lifetimes of about 4.7 min for (1)H spins in [D4]MeOH are seen in this system.
核磁共振（NMR）光谱和磁共振成像（MRI）已成为许多研究领域的重要技术。这些方法的一个主要局限性是相对较低的灵敏度，最近通过超极化得到了解决。然而，一旦将极化赋予分子，磁化通常在相对较短的时间内衰减。单重态与环境很好地隔离，从而获得长寿命。我们在此描述了一种使用硫醇加成反应读出马来酸二甲酯中超极化长寿命态的模型反应。这种类型的反应可以通过对硫醇的灵敏检测来监测氧化应激或缺氧。类似的反应可以用于生物传感器或利用分子开关的测定。在该体系中，[D4]MeOH 中（1）H 自旋的单重态寿命约为 4.7 分钟。
