Elementary Steps in Gold Photocatalysis

黄金光催化的基本步骤

• 批准号: 404389667
• 负责人: Professor Dr. Andreas Dreuw
• 金额: --
• 依托单位: Chair of Theoretical and Computational Chemistry
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/404389667?language=en
• 关键词: Elementary; Steps; Gold; Photocatalysis

Despite great progress, many key steps in photocatalysis involving dinuclear gold(I) complexes or mononuclear gold(III) complexes remain poorly understood. A detailed understanding of elementary reactions and key intermediates is therefore crucial to conceptually design new synthetic routes. As such, the formation of free “alkynyl radicals” in the reaction of dinuclear gold complexes with iodo-substituted alkynes remains highly doubtable. Therefore, a central question involves the origin of such “alkynyl radical”-derived products and other present reactive species. In this regard the formation of gold-alkynyl species could be feasible. Thus, the exact mechanistic steps need to be elucidated.Gold-catalyzed electron transfer mechanisms were already proposed for dinuclear gold complexes as well as gold(III) complexes. In case of the dinuclear complex which does not absorb the light of blue LEDs, a base is necessary in order to form a gold-base aggregate so that the use of highly energetic UVA light can be avoided. The nature of this intermediate still needs to be clarified. For this, a combined experimental/computational approach is required. Experimental mechanistic studies consist of in situ spectroscopy, stoichiometric control experiments, fluorescence quenching experiments and isolation of key intermediates. In this regard, isolation of key intermediates could be achieved by modification of the substrates or metal complex guided by a theoretical approach. With a theoretical description of the photocatalytic behavior of dinuclear gold complexes being rare in comparison to their experimental application, a comprehensive computational protocol will first be developed. This not only enables the investigation of the energetics of such reaction mechanisms but also the calculation of excited state properties. This will be employed for the identification of photoactive intermediates and for the thorough evaluation of the subsequent catalytic steps within dinuclear Au-photocatalysis. Key features within this examination of the catalytic cycle will be the prediction of spectroscopic signatures of suspected intermediates for experimental verification as well as the computation of the energetic profile of the mechanism. Furthermore the protocol will be instrumental for the systematic theoretical elucidation of differences between SET and EnT mechanisms in dinuclear gold photocatalysis.

尽管取得了巨大进展，但光催化中涉及双核金（I）配合物或单核金（III）配合物的许多关键步骤仍然知之甚少。因此，详细了解基本反应和关键中间体对于概念性设计新的合成路线至关重要。因此，双核金配合物与碘取代炔的反应中游离“炔基”的形成仍然非常值得怀疑。因此，一个中心问题涉及这种“炔基自由基”衍生产物和其他存在的活性物质的起源。在这方面，金-炔基物质的形成是可行的。因此，需要阐明确切的机制步骤。金催化电子转移机制已经被提出用于双核金配合物以及金（III）配合物。如果双核络合物不吸收蓝色LED的光，则需要碱来形成金基聚集体，从而可以避免使用高能UVA光。该中间体的性质仍需澄清。为此，需要结合实验/计算方法。实验机理研究包括原位光谱、化学计量控制实验、荧光猝灭实验和关键中间体的分离。在这方面，关键中间体的分离可以通过在理论方法指导下修饰底物或金属络合物来实现。与实验应用相比，双核金配合物光催化行为的理论描述很少见，因此首先将开发一个全面的计算协议。这不仅可以研究此类反应机制的能量学，还可以计算激发态特性。这将用于光活性中间体的鉴定以及双核金光催化中后续催化步骤的彻底评估。催化循环检查的关键特征是预测可疑中间体的光谱特征以进行实验验证以及计算该机制的能量分布。此外，该协议将有助于系统地理论阐明双核金光催化中 SET 和 EnT 机制之间的差异。