Hybrid Supramolecular Water Oxidation Catalysts for Massive Electrochemical Response

自然界数千年来在光合作用中以化学键的形式再生储存太阳能。在将能源生产从化石燃料转变为可再生能源方面，人工光合作用设备的开发可以发挥巨大的作用。储存在化学键中的能量具有较高的能量密度，便于运输。因此，化学能载体可以很容易地存储和分散使用，通过现有的技术，这是一个关键的优势，相对于发电，例如太阳能电池。人工光合作用系统发展的瓶颈是水被氧化成氧气。在过去的几年里，水氧化分子催化剂的合成取得了巨大的优势，反应速度现在可以与自然界的反应速度相媲美。该项目旨在进一步提高用于裂水装置的分子水氧化催化剂的反应速度和稳定性。Llobet教授和他在西班牙ICIQ的同事们对水氧化催化反应机理的深入了解导致了迄今为止最好的分子水氧化催化剂[Ru(TDA)(Py)2]的开发。这种催化剂通过极性反转的氧原子对水分子的亲电攻击建立了氧键。在自然界中，这种亲电攻击的激活能因蛋白质环境中水分子的预组织而减少。在项目的第一部分，应该通过Ru-TDA催化剂的大环排列来引入这种预组织。因此，我想将Ru-TDA催化剂与不同的联吡啶配体结合起来，创造出不同空腔大小的超分子催化剂。然后对得到的配位齐聚物进行密集的结构和电化学研究，以确定空穴大小对催化性能的影响。我想利用第一部分的结果来设计一维、二维和三维配位聚合物，这些聚合物基于由多吡啶配体连接的Ru-TDA催化剂，具有定义的、最佳的孔尺寸。这种多孔金属有机骨架非常适合在其空腔中预组织水分子，这应该会提高催化剂的反应速度，同时提供更高的稳定性。因此，聚合物水氧化催化剂可以为人工光合作用装置的发展做出巨大贡献。

The regenerative storage of solar energy in chemical bonds is performed by nature for millennia in photosynthesis. The development of artificial photosynthetic devices can have a huge share in changing the energy production from fossil fuels towards renewable energy sources. Energy stored in chemical bond has a high energy density and is easy to transport. Thus, chemical energy carriers can be easily stored and used decentralized by established techniques, which is a crucial advantage over electric generated energy, e.g. from solar cells. The bottle neck in the development of artificial photosynthetic systems is the oxidation of water to dioxygen. The synthesis of molecular catalysts for water oxidation has made huge advantages over the last years and reaction rates are now comparable to those in nature. The project intents to further increase the reaction rates and the stability of molecular water oxidation catalysts for application in water splitting devices. Increased understanding of the reaction mechanisms in water oxidation catalysis led to the development of the, up to now, best molecular water oxidation catalyst [Ru(tda)(py)2] by Prof. Llobet and his coworkers at the ICIQ in Spain. The dioxygen bond is built by this catalyst via an electrophilic attack of a polarity inversed Oxygen atom on a water molecule. In nature, the activation energy for this electrophilic attack is reduced by the pre-organization of water molecules by a protein environment. In the first part of the project this pre-organization should be introduced by a macrocyclic arrangement of Ru-tda catalysts. Therefore, I want to combine the Ru-tda catalyst with different bipyridyl ligands, to create supramolecular catalysts with varying cavity sizes. The obtained coordination oligomers will then be subject to intense structural and electrochemical investigation to determine the influence of the cavity size on the catalytic properties. I want to use the results from this first part to design 1D, 2D, and 3D coordination polymers with defined, optimal pore sizes based on the Ru-tda catalyst linked by polypyridyl ligands. Such porous metal organic frameworks will be ideally fit to pre-organize water molecules in their cavities, which should enhance the reaction rate of the catalyst while providing elevated stability. Thus, polymeric water oxidation catalysts can make a huge contribution to the development of artificial photosynthetic devices.