Scheller Zoe Nonie, Schulte Jan, Wölper Christoph, Haberhauer Gebhard
Institut für Organische Chemie, Universität Duisburg-Essen, Universitätsstr. 7, D-45117, Essen, Germany.
Chemistry. 2025 Aug 13;31(45):e01571. doi: 10.1002/chem.202501571. Epub 2025 Jul 22.
In recent years, chalcogen bonding has emerged as a promising alternative to classical supramolecular interactions such as hydrogen or halogen bonds. While its behavior in the electronic ground state has been extensively studied, its role in the excited state is gaining increasing attention. We recently demonstrated that the lack of photoswitchability of ortho-tellurated azobenzenes is due to an excitation-induced conversion of the classical chalcogen bond into a more pronounced, electron-rich three-electron σ bond. This transformation significantly strengthens the interaction between the chalcogen and the Lewis base center, effectively preventing isomerization. Based on these findings, we have now investigated the photoswitching behavior of ortho-tellurium-substituted azoarenes by modulation of the electronic properties of the aryl substituent and the oxidation state of the tellurium center. Our results show that electron-donating groups destabilize the excited-state geometry associated with the formation of a three-electron σ bond, thereby restoring photoisomerizability. Furthermore, oxidation to the Te(IV) species disrupts this bonding interaction, leading to significantly enhanced photoswitching properties. Together, these findings provide valuable design principles for the development of multiresponsive molecular switches based on chalcogen bonding and excited-state control.
近年来，硫属元素键已成为一种有前景的替代经典超分子相互作用（如氢键或卤键）的方式。虽然其在电子基态的行为已得到广泛研究，但其在激发态的作用正受到越来越多的关注。我们最近证明，邻位碲化偶氮苯缺乏光开关性是由于激发诱导经典硫属元素键转化为更显著的、富电子的三电子σ键。这种转变显著增强了硫属元素与路易斯碱中心之间的相互作用，有效地阻止了异构化。基于这些发现，我们现在通过调节芳基取代基的电子性质和碲中心的氧化态，研究了邻位碲取代偶氮芳烃的光开关行为。我们的结果表明，供电子基团会使与三电子σ键形成相关的激发态几何结构不稳定，从而恢复光异构化能力。此外，氧化为Te(IV)物种会破坏这种键合相互作用，导致光开关性能显著增强。总之，这些发现为基于硫属元素键合和激发态控制的多响应分子开关的开发提供了有价值的设计原则。
