Paradigm Shift in Triplet-Triplet Energy Transfer Catalysis: Towards Earth Abundant Transition Metals and Low Photon Energies

你怎么了通过三重态-三重态能量转移（TTEnT）催化活化底物代表了有机合成中朝向高效、选择性和温和使用（可见）光的关键技术。然而，与此同时，该领域在可持续性和有限的光子能量方面面临着严峻的挑战。这些问题在这个跨学科的项目提案中得到了解决，该提案建立在合成化学（Glorius）和物理化学（Guldi）的主要贡献之上。在TTEnT工艺合理化和优化TTEnT催化剂设计的基础上，开发了两个紧密交织的工作包，以启动TTEnT工艺领域的范式转变：第一个工作包的重点是开发可持续催化剂，避免对稀有贵金属（Ru，Ir）的需求。为此，将实现催化剂的计算建模、合成和物理表征的集成管道。根据系统优化的卡宾基配体图案，发射钴（III）配合物将获得，其TTENT活性将随后进行评估。瞬态中红外光谱是这方面的一项关键技术，可以对潜在的分子过程进行详细表征。第二个工作包解决了使用双光子过程在温和的条件下解锁高能激发态。其中一个重点将是开发基于三重态-三重态湮灭过程的高效维斯→UV上转换级联。为此，将进行潜在敏化剂-湮灭剂-催化剂三元组的组合评估，以最终实现底物的TTEnT活化。该评估与使用时间分辨光谱的生物物理表征以及外部刺激（如磁场）的调查密切相关。从长远来看，这两个工作包不仅有助于更深入地了解TTENT过程，而且还在有机合成及其他方面开辟了多个视角-由于向可持续系统和低激发能的范式转变。

Quo vadis, photocatalysis? The catalytic activation of substrates by triplet-triplet energy transfer (TTEnT) represents a key technology in the context of organic synthesis towards efficient, selective and mild use of (visible) light. At the same time, however, the field faces crucial challenges in terms of sustainability and limited photonic energy. These problems are addressed in this interdisciplinary project proposal, which is built on main contributions from synthetic (Glorius) and physical chemistry (Guldi). Building on previous work on the rationalization of TTEnT processes and the design of optimized TTEnT catalysts, two closely interwoven work packages have been developed to initiate a paradigm shift in the field of TTEnT processes:The focus of the first work package is on the development of sustainable catalysts that avoid the need for rare noble metals (Ru, Ir). To this end, an integrated pipeline of computational modeling, synthesis, and photophysical characterization of catalysts will be realized. Under systematic optimization of the carbene-based ligand motifs, emissive cobalt(III) complexes are to be obtained, whose TTEnT activity will be subsequently evaluated. Transient midIR spectroscopy represents a key technology in this regard, allowing for a detailed characterization of the underlying molecular processes. The second work package addresses the use of two-photon processes to unlock high-energy excited states under mild conditions. One focus will be the development of efficient Vis→UV upconversion cascades based on triplet-triplet annihilation processes. For this purpose, a combinatorial evaluation of potential sensitizer-annihilator-catalyst triads will be performed to ultimately enable TTEnT activation of substrates. This evaluation goes hand in hand with photophysical characterization using time-resolved spectroscopy, as well as the investigation of external stimuli such as magnetic fields. In the long term, these two work packages not only contribute to a deeper understanding of TTEnT processes, but also open multiple perspectives in the context of organic synthesis and beyond – owing to the paradigm shift towards sustainable systems and low excitation energies.