Relative Solution Electron Affinities of Selectively Deuteriated Pyrenes: Correlations between Voltammetric, Electron Paramagnetic Resonance, and Semiempirical PM3 Data
摘要:
The equilibrium isotope effects (EIE) for the one-electron transfer between pyrene and seven regioselectively deuteriated pyrene isotopic isomers in dimethylformamide with 0.1 M tetrabutylammonium hexafluorophosphate were measured electrochemically. These data correlate linearly with the free energies (Delta G(o)) obtained in tetrahydrofuran using electron paramagnetic resonance (EPR) techniques. However, the slope of the resulting line is not unity, and it indicates that the EIE in the DMF system is only two-thirds of that in the THF system. PM3 calculated Delta G(o,)s, which would correspond to the gas phase electron transfers, also correlate linearly with both sets of experimental data, but the predicted magnitudes of the EIE's are smaller than those observed experimentally by either technique. The nonunity slopes probably reflect slight differences in ion solvation and/or ion association parameters between the anion radicals of the isotopic isomers. No general relationship between the EIE and the charge on the hydrogen/deuterium substituted carbon atom was found.
Upon encapsulating an oval-shaped hydrocarbon guest, a cylindrical host deforms its shape to maximize intermolecular contacts. Structure-assembly relationship studies with a series of hydrocarbon guests disclosed the importance of molecular shapes and CH-π contacts. Multiple contacts and weak CH-π hydrogen bonds resulted in an optimal assembly; however, the shape deformation resulted in severe retardation
Global Tracking of Transformation Products of Environmental Contaminants by <sup>2</sup>H-Labeled Stable Isotope-Assisted Metabolomics
作者:Ke Chen、Yuhui Xiang、Xiaoyu Yan、Zhenghui Li、Rui Qin、Jie Sun
DOI:10.1021/acs.analchem.2c00500
日期:2022.5.24
isotope-assisted metabolomics (SIAM) enables global tracking of isotopic labels in nontargeted metabolomics in living organisms. However, its application in tracking transformation products (TPs, as metabolites of contaminants) of environmentalcontaminants is still a challenge due to limits in methodology, unmatured algorithms, and the high cost of 13C-labeled contaminants. Therefore, we developed a 2H-SIAM
稳定同位素辅助代谢组学 (SIAM) 能够对活生物体中非靶向代谢组学中的同位素标记进行全局跟踪。然而,由于方法学的限制、不成熟的算法以及13 C 标记污染物的高成本,其在跟踪环境污染物转化产物(TPs,作为污染物的代谢物)中的应用仍然是一个挑战。因此,我们开发了一个2 H-SIAM 管道以及高度灵活的算法2 H-SIAM(1.0) (https://github.com/kechen1984/2H-SIAM),便于跟踪环境基质中污染物的 TP。详细讨论说明了2 H-SIAM的理论、行为和前景。我们证明了提议的2H-SIAM 管道相对于13 C-SIAM具有独特的优势,例如经济高效的2 H 标记污染物、易于合成2 H 标记的新兴污染物以及提供更多的结构信息。芘土壤退化研究进一步证实了它的高性能。它有效地丢弃了 99% 的噪声信号,并从非靶向高分辨率质谱 (HRMS) 数据中提取了 52 个特