Thermal and photochemical assembly of light-harvesting complexes: an electrochemical, optical and computational investigation.

太阳能将光能转化为化学能，使人类有可能放弃目前对化石燃料的依赖。这一向替代能源迈进的步骤将遏制全球变暖，并为子孙后代保证更清洁的环境。在这个发现补助金申请中，我建议使用配位和超分子化学来模拟自然光合作用，以组装能够在大部分可见光谱范围内捕获阳光的捕光复合物。我们还建议使用一种新的合成方法的基础上光化学照射，以产生我们的寡和多金属捕光复合物。这种新方法是基于这样一个事实，即金属-配体键的光激发在某些情况下可以破坏这些键。通过精心设计和合成配体，我们可以决定在任何给定的金属络合物中哪些键会断裂，哪些键不会断裂。例如，由于螯合作用，二齿和三齿配体比单齿配体更稳定。通过将所有三种类型的配体结合到同一复合物中，我们可以将光反应推向仅排出单齿配体。事实上，仔细的设计甚至可以决定一个特定的单齿配体的损失超过另一个。设想了含有金属离子如Ru、Pt、Re和Ir的正方形、六边形和八边形的自组装。这些多金属配合物将被光化学组装，并通过电化学和光谱实验进行检查，以充分了解其基本性质。然后，它们将被纳入光催化系统，以检查化学能的产生。新的助催化剂将使我们能够从水中生产氢气。我的小组开发了一种新的仪器技术，这将使我们能够监测光反应的紫外-可见吸收光谱，同时监测二氢的产生。这种强大的新技术将使我们能够更深入地探索催化循环，并开发下一代光催化剂和捕光复合物。

Solar energy conversion of light into chemical energy offers humankind the possibility to forgo our current dependence on fossil fuels. This step forward towards alternative energy would curb global warming and guarantee a cleaner environment for future generations. In this Discovery Grant application, I propose to mimic natural photosynthesis using coordination and supramolecular chemistry to assemble light-harvesting complexes capable of capturing sunlight over most of the visible spectrum. We also propose to use a new synthetic methodology based on photochemical irradiation to produce our oligo- and poly-metallic light-harvesting complexes. This new approach is based on the fact that light excitation of metal-ligand bonds can in some instances break these bonds. By careful design and synthesis of ligands we can dictate which bonds will break and which bonds will not in any given metal complex. For example, bi- and tri-dentate ligands are more stable than mono-dentate ligands due to the chelate effect. By incorporating all three types of ligands into the same complex, we can push photoreactions towards the ejection of the mono-dentate ligand only. Indeed, careful design can even dictate the loss of one particular mono-dentate ligand over another. The self-assembly of squares, hexagons and octagons containing metal ions such as Ru, Pt, Re and Ir is envisaged. These multimetallic complexes will be photochemically assembled and examined by electrochemical and spectroscopic experiments to fully understand their fundamental properties. They will then be included into photocatalytic systems to examine the production of chemical energy. New Co-catalysts will allow us to produce dihydrogen from water. A new instrumental technique was developed in my group which will allow us to monitor the UV-visible absorption spectroscopy of the photoreaction while we monitor dihydrogen production. This powerful new technique will allow us to probe deeper into the catalytic cycle and develop the next generation of photocatalysts and light-harvesting complexes.