Wiengarten Alissa, Lloyd Julian A, Seufert Knud, Reichert Joachim, Auwärter Willi, Han Runyuan, Duncan David A, Allegretti Francesco, Fischer Sybille, Oh Seung Cheol, Sağlam Özge, Jiang Li, Vijayaraghavan Saranyan, Écija David, Papageorgiou Anthoula C, Barth Johannes V
Physik Department E20, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany).
Current address: Department of Materials Engineering, Monash University Clayton Campus, VIC 3800 (Australia).
Chemistry. 2015 Aug 24;21(35):12285-90. doi: 10.1002/chem.201502001. Epub 2015 Jul 16.
Selectivity in chemical reactions is a major objective in industrial processes to minimize spurious byproducts and to save scarce resources. In homogeneous catalysis the most important factor which determines selectivity is structural symmetry. However, a transfer of the symmetry concept to heterogeneous catalysis still requires a detailed comprehension of the underlying processes. Here, we investigate a ring-closing reaction in surface-confined meso-substituted porphyrin molecules by scanning tunneling microscopy, temperature-programmed desorption, and computational modeling. The identification of reaction intermediates enables us to analyze the reaction pathway and to conclude that the symmetry of the porphyrin core is of pivotal importance regarding product yields.
化学反应的选择性是工业生产过程中的一个主要目标，旨在将虚假副产物降至最低并节省稀缺资源。在均相催化中，决定选择性的最重要因素是结构对称性。然而，将对称性概念应用于多相催化仍需要对其潜在过程有详细的理解。在此，我们通过扫描隧道显微镜、程序升温脱附以及计算模拟，研究了表面受限的中位取代卟啉分子中的闭环反应。反应中间体的鉴定使我们能够分析反应途径，并得出结论：卟啉核心的对称性对于产物产率至关重要。
