Development Novel Photosensitiser Materials Based on Earth-Abundant Elements

以Ru和Ir等金属为基础的光物理感光器材料提供了卓越的性能，并提供了调整和优化其性能的途径。然而，用更便宜、更丰富的第一排过渡金属元素取代这些稀有而昂贵的元素远不是一项简单的任务。在低自旋d6铁(II)类似物中，金属-配体电荷转移(MLCT)态被金属中心(MC)态和高自旋态(Ru不能进入)迅速失活，这些态是Ru(II)d6配合物吸引人的性质的原因。解决这种情况的一种典型方法是通过增加配体的施主强度来增加d轨道的分裂和提高这些有害的MC态的能量。然而，这种方法只取得了有限的成功。在现代无机化学中，这是一个当前非常热门的领域，人们已经从试图迫使铁(II)表现为Ru(II)的行为转向探索更轻元素络合物的替代电子构型，并利用它们自己独特的光物理性质。这导致了基于d5 Fe(III)，d3 Cr(III)和d0 Zr(IV)的材料表现出与传统MLCT状态不同的电子性质的激发态，具有记录的寿命和光催化性能。在这个项目中，将致力于开发基于更轻的富含地球的金属的新型光敏材料。这将涉及合成新的配体及其络合物。所得到的材料的光物理和电化学性质将通过稳态方法得到彻底的表征。还将与世界领先的国家和国际伙伴合作，在计算化学计算的支持下，利用超快瞬时吸收光谱方法对材料进行研究。在最终用户需求的指导下，络合物的合成设计将被告知，并最终用于调解具有挑战性的光催化有机转化和聚合反应。

Photophysical sensitiser materials based on metals such as ruthenium and iridium offer superb performance and avenues for tuning and optimisation of their properties. However, it is a far from simple task to substitute these rare and expensive elements by cheaper and more-abundant first row transition metal elements. The metal-to-ligand charge transfer (MLCT) states that are responsible for the attractive properties of ruthenium(II) d6 complexes are rapidly deactivated in their low-spin d6 iron(II) analogues by metal-centred (MC) states that are much lower lying than for ruthenium and also high-spin states that are inaccessible for ruthenium. A typical approach to remedy this situation has relied upon increasing the donor strength of ligands to increase the d-orbital splitting and raise the energies of these deleterious MC states. However, this approach has only had limited success.In what is a current and extremely hot area in modern inorganic chemistry there has been a move away from attempting to force iron(II) to behave like ruthenium(II) and instead explore alternative electronic configurations of complexes of lighter elements and exploit their own unique photophysical properties. This has led to materials based on d5 Fe(III), d3 Cr(III) and d0 Zr(IV) that exhibit excited states of different electronic character to traditional MLCT states, have record lifetimes and have potent photocatalytic properties.In this project the development of new photosensitiser materials based on lighter Earth-abundant metals will be targeted. This will involve the synthesis of new ligands and their complexes. The photophysical and electrochemical properties of the resultant materials will be thoroughly characterised by steady state methods. In collaboration with world-leading national and international partners materials will also be investigated by ultrafast transient absorption spectroscopy methods with work supported by computational chemistry calculations. Guided by end user needs the synthetic design of complexes will be informed by, and ultimately used to mediate challenging photocatalytic organic transformations and polymerisation reactions.