[论文解读] Reshaping and quantifying inter- and intramolecular exchange in signal amplification by reversible exchange of pyruvate

Charbel D. Assaf, Vladimir V. Zhivonitko+5 more|arXiv (Cornell University)|Jan 7, 2026

Advanced NMR Techniques and Applications被引用 1

一句话总结

该论文使用对氢增强、自旋选择性的NMR，并结合交换模型拟合与DFT，解析基于SABRE的丙酮酸极化，揭示分子内氢交换、一个新Ir络合物，以及对结合的离子效应。

ABSTRACT

Signal amplification by reversible exchange (SABRE) is a nuclear spin hyperpolarization technique in which the transient interaction of parahydrogen (pH2) and a target substrate with an iridium complex leads to polarization transfer to the substrate. Here, we use a parahydrogen-enhanced, spin-selective NMR method to investigate pyruvate binding, which is combined with exchange-model fitting and DFT calculations. Our study reveals several key findings that reshape the current understanding of SABRE: (a) intramolecular hydrogen exchange of the hydrides, occurring faster than pyruvate or H2 loss; (b) the discovery of a novel stable H2-IrImes-DMSO2-pyruvate complex; and (c) the crucial role of counterions, here Na+, in Ir-pyruvate binding. Previously unknown insights into complex kinetics and distributions as a function of temperature, [DMSO], [pyruvate], and hydrogen pressure are presented. The methods demonstrated here, exemplified by SABRE, provide a framework that is expected to guide future research in the field.

研究动机与目标

• 研究SABRE在极化丙酮酸过程中的详细化学交换过程。
• 阐明SABRE体系内分子内的氢交换动力学。
• 识别新的配位物种及影响Ir-丙酮酸结合的因子。
• 量化温度、溶剂(DMSO)、底物浓度和氢气压力如何影响动力学与分布。

提出的方法

• 采用对氢增强、自旋选择性NMR来探测丙酮酸与铱络合物的结合与交换。
• 将交换模型拟合与密度泛函理论(DFT)计算结合以解释动力学数据。
• 表征新稳定Ir络合物：[Ir(H)2(IMes)(kappa1-pyr)(DMSO)2]的形成。
• 评估对离子(Na+)对Ir-丙酮酸结合与络合物稳定性的影响。

实验结果

研究问题

• RQ1 支配丙酮酸SABRE极化的关键动力学步骤与交换路径是什么？
• RQ2 分子内氢交换在水合氢(H hydride)中的速率与底物或H2损失相比如何？
• RQ3 SABRE体系中形成了哪些新的配位物种，对离子如何影响结合？
• RQ4 实验变量(温度、DMSO、丙酮酸浓度、H2压力)如何影响络合物动力学与分布？

主要发现

• 分子内水合氢交换速率快于丙酮酸或H2的损失。
• 识别出一个新稳定络合物：[Ir(H)2(IMes)(kappa1-pyr)(DMSO)2]。
• 对离子如Na+可影响Ir-丙酮酸的结合。
• 研究绘制了络合物在温度、DMSO、丙酮酸与氢气压变化下的动力学与分布。
• 所用方法为未来SABRE研究提供了可推广的框架。