Organic sulfoxides, a group of compounds containing the sulfinyl SO group, are widespread in nature, important in health and disease, and used in a variety of applications in the pharmaceutical industry. We have examined the sulfur K-edge X-ray absorption near-edge spectra of a range of different sulfoxides and find that their spectra are remarkably similar. Spectra show an intense absorption peak that is comprised of two transitions; a S 1s → (S–O)σ* and a S 1s → [(S–O)π* + (S–C)σ*] transition. In most cases these are sufficiently close in energy that they are not properly resolved; however for dimethylsulfoxide the separation between these transitions increases in aqueous solution due to hydrogen bonding to the sulfinyl oxygen. We also examined tetrahydrothiophene sulfoxide using both the sulfur and oxygen K-edge. This compound has a mild degree of ring strain at the sulfur atom, which changes the energies of the two transitions so that the S 1s → [(S–O)π* + (S–C)σ*] is below the S 1s → (S–O)σ*. A comparison of the oxygen K-edge X-ray absorption near-edge spectra of tetrahydrothiophene sulfoxide with that of an unhindered sulfoxide shows little change, indicating that the electronic environment of oxygen is very similar.

中文翻译：

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有机亚砜的 X 射线吸收光谱

有机亚砜，一组含有亚磺酰基 S 的化合物O 基团在自然界中广泛存在，对健康和疾病很重要，并用于制药行业的各种应用中。我们检查了一系列不同亚砜的硫 K 边 X 射线吸收近边光谱，发现它们的光谱非常相似。光谱显示由两个跃迁组成的强烈吸收峰；一个 S 1s → (S–O)σ* 和一个 S 1s → [(S–O)π* + (S–C)σ*] 跃迁。在大多数情况下，它们的能量足够接近，无法正确解决；然而，对于二甲亚砜，这些转变之间的分离在水溶液中由于与亚磺酰基氧的氢键合而增加。我们还使用硫和氧 K 边缘检查了四氢噻吩亚砜。该化合物在硫原子处具有温和程度的环应变，它改变了两个跃迁的能量，使得 S 1s → [(S–O)π* + (S–C)σ*] 低于 S 1s → (S–O)σ*。将四氢噻吩亚砜的氧 K 边 X 射线吸收近边光谱与未受阻亚砜的 K 边 X 射线吸收近边光谱进行比较，结果几乎没有变化，表明氧的电子环境非常相似。