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。向替代能源迈进的这一步将遏制全球变暖，并为子孙后代保证一个更清洁的环境。在这一发现基金申请中，我建议使用配合和超分子化学来模拟自然光合作用，以组装能够捕获大多数可见光谱的阳光的光收集复合物。我们还建议使用一种新的基于光化学照射的合成方法来生产我们的寡金属和多金属光捕获配合物。这种新方法是基于金属-配体键的光激发在某些情况下可以破坏这些键的事实。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配合物中哪些键会断裂，哪些键不会断裂。例如，由于螯合作用，双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个配合物中，我们可以推动光反应只向单齿配体的射出。事实上，精心的设计甚至可以决定一种特定的单齿配体在另一种配体上的损失。设想了包含Ru、Pt、Re和Ir等金属离子的方形、六边形和八边形的自组装。这些多金属配合物将进行光化学组装，并通过电化学和光谱实验进行检测，以充分了解它们的基本性质。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二氢。我的小组开发了一种新的仪器技术，它将使我们能够在监测二氢产生的同时监测光化学反应的紫外可见吸收光谱。这项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光收集复合物。

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.