Metal cooperativity for visible-light driven CO2 reduction with new photosensitizers and catalysts (CO2-COP)

二氧化碳的催化还原是一个非常活跃和具有挑战性的研究领域。尤其是二氧化碳的光催化循环及其作为碳原料的利用可能会对全球碳平衡产生严重影响，因为它可以降低温室气体排放，类似于自然光合作用的途径。为此，化学通过应对根本的科学挑战，在开发此类技术方面发挥了关键作用。因此，卓越的催化剂开发是至关重要的，均相和多相方法都得到了广泛的追求。由于可利用的光谱技术众多且易于合成改变，对分子过渡金属络合物的研究对于从机理上洞察结构非常明确的体系至关重要，因此对开发选择性二氧化碳还原过程的基本策略具有极大的吸引力。这种方法需要合成配位化学家、光化学家、电化学家和光谱学家的专门知识，在此将由Wenger、Apfel和Robert小组共同努力尝试。受大自然的启发，利用酶促双金属活性中心选择性地激活二氧化碳，通过金属合作促进和选择性地进行多电子/多质子还原，将只使用地球上丰富的金属来合理地开发合成的双金属络合物。此外，通过有针对性地设计配体主链结构来调节和控制金属的协同性，我们将致力于在可见光驱动的过程中由二氧化碳选择性地合成甲醇、甲烷或短链碳氢化合物。然而，为了实现光驱动的二氧化碳还原，这些新的催化系统同样需要新的合适和有效的光敏剂。因此，由富含稀土的过渡金属制成的光敏剂将被合成并研究其光物理性质。因此，光敏剂和催化剂将在所有基团之间以迭代过程同步。这些发现将对整个光化学，特别是对二氧化碳的减少和活化产生深远的影响。

The catalytic reduction of carbon dioxide (CO2) represents a highly active and challenging research field. Especially the photocatalytic recycling of CO2 and its utilization as a carbon feedstock could show severe impact on the global carbon balance as it allows to lower greenhouse gas emissions analog to natural photosynthesis pathways. Towards that end, chemistry plays a key role in developing such technologies by addressing the fundamental scientific challenges. Herein, pre-eminent catalyst development is of paramount importance and both homogenous and heterogeneous approaches are widely pursued. Due to the numerous spectroscopic techniques available and ease of synthetic alterations, studies on molecular transition metal complexes are vital for obtaining mechanistic insight on structurally very well-defined systems and are thus highly attractive to develop fundamental strategies for selective CO2 reduction processes. This approach requires the know-how of synthetic coordination chemists, photochemists, electrochemists and spectroscopists and will herein be attempted by joint efforts of the Wenger, Apfel and Robert groups. Inspired by Nature that enables selective activation of CO2 utilizing enzymatic bi-metallic active sites with a facilitated and selective multi-electron/multi-proton reduction through metal cooperativity, synthetic bi-metallic complexes will be rationally developed employing only earth-abundant metals. Furthermore, by tuning and controlling the metal cooperativity by targeted design of ligand backbone structures, we will aim at a selective synthesis of methanol, methane or short-chain hydrocarbons from CO2 in visible-light driven processes. To enable a light-driven CO2 reduction, these novel catalytic systems, however, likewise require novel suitable and potent photosensitizers. Thus, photosensitizers made from earth abundant transition metals will be synthesized and investigated for their photophysical properties. Consequently, the photosensitizers and catalysts will be synchronized in an iterative process between all groups. These findings will have far-reaching implications for photochemistry in general, as well as for CO2 reduction and activation in particular.