Turowska-Tyrk I
Department of Chemistry, Wrocław University of Technology, Poland.
Chemistry. 2001 Aug 3;7(15):3401-5. doi: 10.1002/1521-3765(20010803)7:15<3401::aid-chem3401>3.0.co;2-f.
The studies presented are the first example in which the substrate and product molecules were monitored separately over many stages during the chemical reaction progress in a crystal to understand the reaction path of the molecules in detail during the whole transformation. The BBCP, 2-benzyl-5-benzylidenecyclopentanone, single crystal was irradiated without any destruction over several steps. After each of step the X-ray structure with a different substrate/product ratio and with a disorder was determined. The study revealed that the photochemical [2+2]-cycloaddition reaction of BBCP in a crystal does not exhibit cooperative character and can be regarded as of the first-order. During the transformation the product molecules do not adopt the position of the molecules in the final pure dimer crystal, but move gradually and smoothly in this direction. The movement of the molecules was also observed for the substrate. This remarkable behaviour of the product and reactant molecules bears a rotational component. The distance between reaction centres of adjacent BBCP substrate molecules decreases fluently with the progress of the reaction, but it does not get smaller than a sum of van der Waals radii.
所展示的这些研究是首个实例，即在晶体化学反应进程的多个阶段中分别监测底物和产物分子，以详细了解分子在整个转化过程中的反应路径。对2-苄基-5-亚苄基环戊酮（BBCP）单晶进行了几步辐照，且未造成任何破坏。每一步之后，都测定了具有不同底物/产物比例且存在无序情况的X射线结构。研究表明，BBCP在晶体中的光化学[2+2]环加成反应不具有协同特性，可视为一级反应。在转化过程中，产物分子并非占据最终纯二聚体晶体中分子的位置，而是朝着这个方向逐渐且平稳地移动。对于底物分子也观察到了这种移动。产物和反应物分子的这种显著行为带有一个旋转分量。随着反应的进行，相邻BBCP底物分子反应中心之间的距离持续减小，但不会小于范德华半径之和。
