Division of Advanced Materials Science, Pohang University of Science and Technology, RIST Building 3-3390, 77 Cheongam-Ro, Nam-Gu, Pohang, Republic of Korea.
Division of Advanced Materials Science, Pohang University of Science and Technology, RIST Building 3-3390, 77 Cheongam-Ro, Nam-Gu, Pohang, Republic of Korea; Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan.
IUCrJ. 2016 Jun 8;3(Pt 4):232-6. doi: 10.1107/S2052252516008423. eCollection 2016 Jul 1.
The isolation and characterization of small sulfur allotropes have long remained unachievable because of their extreme lability. This study reports the first direct observation of disulfur (S2) with X-ray crystallography. Sulfur gas was kinetically trapped and frozen into the pores of two Cu-based porous coordination networks containing interactive iodide sites. Stabilization of S2 was achieved either through physisorption or chemisorption on iodide anions. One of the networks displayed shape selectivity for linear molecules only, therefore S2 was trapped and remained stable within the material at room temperature and higher. In the second network, however, the S2 molecules reacted further to produce bent-S3 species as the temperature was increased. Following the thermal evolution of the S2 species in this network using X-ray diffraction and Raman spectroscopy unveiled the generation of a new reaction intermediate never observed before, the cyclo-tri-sulfur dication (cyclo-S3 (2+)). It is envisaged that kinetic guest trapping in interactive crystalline porous networks will be a promising method to investigate transient chemical species.
由于其极端的不稳定性，小硫同素异形体的分离和特性描述长期以来一直难以实现。本研究首次通过 X 射线晶体学直接观察到二硫化物（S2）。硫气体通过动力学捕获并冷冻到两个含有相互作用碘原子的基于 Cu 的多孔配位网络的孔中。S2 的稳定化是通过物理吸附或化学吸附在碘阴离子上实现的。其中一个网络仅对线性分子表现出形状选择性，因此 S2 在室温及更高温度下被捕获并在材料中稳定存在。然而，在第二个网络中，随着温度的升高，S2 分子进一步反应生成弯曲的 S3 物种。使用 X 射线衍射和拉曼光谱法研究该网络中 S2 物种的热演化，揭示了从未观察到过的新反应中间体的生成，即环三硫阳离子（环-S3（2+））。预计在相互作用的结晶多孔网络中通过动力学捕获客体将是研究瞬态化学物质的一种很有前途的方法。
