Klosterhalfen Niklas, Singh Nishi, Jäger Michael, Winter Andreas, Köhler Phil, Schubert Ulrich S, Dietzek-Ivanšić Benjamin
Department Functional Interfaces, Leibniz Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Str. 9, Jena, Germany.
Institute for Physical Chemistry (IPC), Friedrich Schiller University Jena, Helmholtzweg 4, Jena, Germany.
Chemistry. 2025 Jun 26;31(36):e202404033. doi: 10.1002/chem.202404033. Epub 2025 Apr 28.
Excited-state proton transfer (ESPT) roots in significantly increased acidities or basicities of up to ca. 10 pK units in the excited state compared to the ground state. While organic photobases are either of "single use" in the case of photobase generators or are limited functionally by their UV absorption, metal complex-based photobases offer intriguing properties. By exciting the characteristic metal-to-ligand charge transfer (MLCT) transitions in the visible range, multiple and reversible ESPT processes can be triggered. In this contribution we present the synthesis of two novel Ruthenium(II)-complexes with pyrazine-functionalized polypyridyl ligands and study their photobasic properties by ultrafast spectroscopy. We find that MLCT excitation in aqueous solution leads to a ΔpK of 9 units and that the involved ESPT process takes place within ca. 300 picoseconds. Our investigations combine experimental spectroscopy with theoretical calculations.
激发态质子转移（ESPT）源于与基态相比，激发态下酸度或碱度显著增加，可达约10个pK单位。虽然有机光碱在光碱发生器的情况下是“一次性使用”的，或者在功能上受其紫外吸收的限制，但基于金属配合物的光碱具有引人入胜的性质。通过在可见光范围内激发特征性的金属到配体的电荷转移（MLCT）跃迁，可以触发多个可逆的ESPT过程。在本论文中，我们报道了两种具有吡嗪功能化多吡啶配体的新型钌（II）配合物的合成，并通过超快光谱研究了它们的光碱性质。我们发现，在水溶液中进行MLCT激发会导致9个单位的ΔpK变化，并且所涉及的ESPT过程在约300皮秒内发生。我们的研究将实验光谱学与理论计算相结合。
