GRK 2112: Molecular Biradicals: Structure, Properties and Reactivity

双自由基在内燃机、大气或星际云等反应环境的化学中起着重要作用。此外，具有双自由基特性的电子态是光电子材料中形成发光态的关键中间体。因此，了解和正确描述具有双自由基电子态的双自由基和分子中的动态过程对化学和物理的许多领域都具有重要意义。这个研究生院的目标是研究具有电子结构的双自由基系统，其特征是两个未成对的电子在简并或接近简并的分子轨道上。它们的化学和物理性质与闭壳分子显著不同，这是由于简并分子轨道导致的能量接近态之间的相互作用。具体地说，我们想要研究双自由基分子结构和性质之间的关系，如取代基对稳定性和自旋多重性的影响。了解电荷分离双自由基态和长寿命三重态的形成和光物理以及环境对这些过程的影响。实验研究和理论描述双自由基激发电子态的结构及其在气相和溶液中的化学反应机理。为了实现这些目标，我们将合成、光谱和理论相结合。将应用的实验方法包括时间域和频域的激光光谱学，也受外部磁场、电子顺磁共振和光谱电化学的影响。电子结构将用量子化学研究，而环境的影响将用量子-经典混合方法建模。对分子动力学的洞察将从表面跳跃动力学和哈密顿模型中获得。我们希望推进对有机双自由基成键的理解，也希望促进对像二硼烯这样的无机物种成键的理解，以便将复杂开壳体系中的现象归结为基本原理。

Biradicals play an important role in the chemistry of reactive environments like combustion engines, the atmosphere or interstellar clouds. Furthermore electronic states with a biradical character are key intermediates in the formation of light-emitting states in optoelectronic materials. It is therefore of relevance for many areas of chemistry and physics to understand and correctly describe the dynamic processes in biradicals and molecules with biradical electronic states. It is the goal of this graduate research school to investigate biradical systems with an electronic structure that is characterized by two unpaired electrons in degenerate or near-degenerate molecular orbitals. Their chemical and physical properties differ significantly from those of closedshell molecules due to the interactions between the energetically close-lying states that result from the degenerate molecular orbitals. Specifically we want to - study the relationship between molecular structure and properties of biradicals, like the influence of substituents on stability and spin multiplicity.- understand the formation and photophysics of charge-separated biradical states and longlived triplet states and the influence of the environment on these processes.- investigate experimentally and describe theoretically the structure of excited electronic states of biradicals and their chemical reaction mechanisms in the gas phase and solution.To achieve these goals, we combine synthesis, spectroscopy and theory. Among the experimental methods that will be applied are laser spectroscopy in the time- and frequency-domain, also under the influence of an external magnetic field, electron paramagnetic resonance and spectroelectrochemistry. The electronic structure will be studied by quantum chemistry, while the influence of the environment will be modelled by quantum-classical hybrid methods. Insight into the molecular dynamics will be obtained from surface hopping dynamics und model Hamiltonians. We want to advance the understanding of bonding in organic biradicals, but also in inorganic species like diborenes, in order to reduce phenomena in complex open-shell systems to fundamental principles.