Dai Yizhe, Wu Gang
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
J Phys Chem A. 2020 Nov 19;124(46):9597-9604. doi: 10.1021/acs.jpca.0c08198. Epub 2020 Nov 5.
We report variable-temperature (VT) O solid-state nuclear magnetic resonance (NMR) spectra for three crystalline sulfonic acids: l-cysteic acid monohydrate (CA), 3-pyridinesulfonic acid (PSA), and -toluenesulfonic acid monohydrate (TSA). We were able to analyze the experimental VT O NMR spectra to obtain the activation barriers for SO jumps in these systems. Using the density functional-based tight-binding (DFTB) method, we performed potential energy surface scans for SO jumps in the crystal lattice of CA, PSA, and TSA, as well as for three related crystalline sulfonic acids (taurine, homotaurine, and 4-aminobutane-1-sulfonic acid) for which relevant O solid-state NMR data are available in the literature. The calculated activation barriers are in reasonable agreement with the experimental values. On the basis of the DFTB results, we hypothesized that activation barriers for SO jumps in the crystal lattice depend largely on the hydrogen bonding energy difference between the ground state and the transition state.
我们报告了三种结晶磺酸的变温（VT）¹⁷O 固态核磁共振（NMR）光谱：L-半胱氨酸一水合物（CA）、3-吡啶磺酸（PSA）和对甲苯磺酸一水合物（TSA）。我们能够分析实验性的 VT¹⁷O NMR 光谱，以获得这些体系中 S=O 跃迁的活化能垒。使用基于密度泛函的紧束缚（DFTB）方法，我们对 CA、PSA 和 TSA 的晶格中 S=O 跃迁进行了势能面扫描，以及对文献中可获得相关¹⁷O 固态 NMR 数据的三种相关结晶磺酸（牛磺酸、高牛磺酸和 4-氨基丁烷-1-磺酸）进行了扫描。计算得到的活化能垒与实验值合理吻合。基于 DFTB 结果，我们推测晶格中 S=O 跃迁的活化能垒在很大程度上取决于基态和过渡态之间的氢键能差。
