Tailoring of heteroleptic copper based photosensitizers and their photophysical characterization

充足和环保的能源供应是本世纪的一大挑战。太阳能利用的增加提供了一个有希望的选择，这需要设计高效、廉价和可持续的光敏剂来收集光。此外，合适的光敏剂应该在可见、长寿命激发态具有强吸收、可逆的电化学行为和高的稳定性，因此分子光敏剂通常是基于稀有和贵金属，如Ir或Ru，限制了其大规模应用。在这种方法中，基于地球上丰富的金属的络合物的使用还相当未被探索。将这种非高尚的制度付诸实践，这是必须改变的。在这方面，具有光活性的铜(I)络合物具有很大的潜力。因此，该项目致力于开发定制的异构型铜(I)光敏剂，并详细研究其(三重态)激发态和电荷转移过程。为此，将采用不同的设计策略，例如通过杂二齿P^N配体交换经典的双膦配体或直接连接双亚胺和双膦配体，以提高稳定性和吸附能力。此外，还将引入额外的电子存储部分，以特定地影响氧化还原性质以及光致电子转移的效率和时间常数。新设计的铜(I)配合物将通过稳态和时间分辨的瞬时吸收和发射光谱进行系统的研究，以阐明潜在的结构-性质关系，并了解激发态的性质。这最终应该导致合成指南，例如，对配体的正确选择、取代基的类型和位置以及电子存储的种类的指示。在迭代过程中，这些发现将立即被用来进一步改进这些铜(I)光敏剂。此外，这些异构性的铜(I)配合物将首次应用于光子上转换过程。总而言之，通过合成、结构和光谱表征以及新型光活性铜(I)络合物的应用，该项目将使异感铜光敏剂成为优先计划SPP 2102的一类有价值的物质。这最终将有助于提高阳光作为一种有前途的清洁能源的利用和转化。

The sufficient and environmentally friendly supply of energy is a major challenge in this century. A promising option is given by the increased use of solar energy, which requires the design of efficient, inexpensive and sustainable photosensitizers for light harvesting. In addition, a suitable photosensitizer should possess a strong absorption in the visible, long-lived excited states, a reversible electrochemical behavior and a high stability.So far molecular photosensitizers are most often based on rare and precious metals, like iridium or ruthenium, limiting their large-scale application. The usage of complexes based on earth-abundant metals in this approach is rather unexplored. To bring such non-noble systems into practice that has to be changed. In this respect photoactive copper(I) complexes possess a great potential.Therefore, the proposed project deals with the development of tailored heteroleptic Cu(I) photosensitizers and the detailed investigation of their (triplet) excited states as well as of their charge-transfer processes. For this purpose different design strategies, e.g. the exchange of classic diphosphine ligands by heterobidentate P^N ligands or a direct connection of the diimine and the diphosphine ligand, will be applied to enhance stability and absorptivity. Furthermore, additional electron storage moieties will be introduced, which allow to affect the redox properties specifically as well as the efficiency and time constant of the photoinduced electron transfer.The newly designed Cu(I) complexes will be systematically studied by steady-state as well as time-resolved transient absorption and emission spectroscopy to elucidate the underlying structure-property relationships and to understand the nature of the excited states. This should ultimately result in synthesis guidelines, e.g. in instructions to the right choice of the ligands, the type and position of substituents and the kind of electron storage. Within an iterative process these findings will be used straight away to further improve these Cu(I) photosensitizers.Moreover, these heteroleptic Cu(I) complexes will be applied for photon upconversion processes for the first time. In consequence, the capability of these compounds to transform photons of low energy into high energy photons, which allows to use a broader range of the light in subsequent reactions, will be clarified.All in all, by the combination of synthesis, structural and spectroscopic characterization as well as application of novel photoactive Cu(I) complexes this project will establish heteroleptic copper photosensitizers as a valuable class of substances for the priority program SPP 2102. This will finally contribute to an increased utilization and conversion of sunlight as a promising and clean energy source.