Semwal Mohini, Vashistha Nikita, Rau Sven, Dietzek-Ivanšić Benjamin
Institute of Physical Chemistry,Friedrich Schiller University Jena, Helmholtzweg 4, Jena 07743, Germany.
Research Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, Jena 07745, Germany.
J Phys Chem A. 2025 Jan 16;129(2):439-446. doi: 10.1021/acs.jpca.4c04914. Epub 2024 Nov 4.
Ru(II)-complexes with photolabile ligands find a wide range of applications, e.g., in drug release and in the design of light-responsive interfaces. While light-driven ligand loss has been studied mechanistically in detail for complexes in solution, comparably few studies are present that investigate the process in a material context, i.e., in a rigid environment and in the absence of solvent. This paper adds to this underrepresented perspective by studying the excited-state dynamics of [Ru(bpy)(nicotine)] (Cl) () as a model system in poly(methyl methacrylate) (PMMA) and polyacrylonitrile (PAN) matrices. Femtosecond transient absorption spectroscopy and time-resolved emission spectroscopy are employed to monitor the photodissociation of labile nicotine ligands in polymer environments. Photoexcitation within the metal-to-ligand charge transfer (MLCT) band leads to transient dissociation of the nicotine ligand when the complex is dissolved in water. However, optical excitation of the MLCT transition of the complexes embedded in polymer matrices does not result in photodissociation, likely due to the rigidity of the environment, which cannot solvate the undercoordinated complex after ligand dissociation and the dissociated ligand. These insights shed light on the role of the local environment when considering the photophysics of ligand loss from Ru(II)-polypyridyl complexes and, hence, their use in the light-activation of reactive molecular components in materials.
含有光不稳定配体的钌（II）配合物有广泛的应用，例如在药物释放和光响应界面设计中。虽然对于溶液中的配合物，光驱动的配体损失已在机理上进行了详细研究，但相对较少有研究在材料背景下，即在刚性环境和无溶剂的情况下研究该过程。本文通过研究[Ru(bpy)(尼古丁)] (Cl) ()在聚甲基丙烯酸甲酯（PMMA）和聚丙烯腈（PAN）基质中的激发态动力学，补充了这一研究较少的视角。飞秒瞬态吸收光谱和时间分辨发射光谱被用于监测聚合物环境中不稳定尼古丁配体的光解离。当配合物溶解在水中时，金属到配体电荷转移（MLCT）带内的光激发会导致尼古丁配体的瞬态解离。然而，嵌入聚合物基质中的配合物的MLCT跃迁的光激发并不会导致光解离，这可能是由于环境的刚性，在配体解离后它无法溶剂化配位不足的配合物和解离的配体。这些见解揭示了在考虑钌（II）-多吡啶配合物配体损失的光物理过程以及它们在材料中活性分子组分的光激活应用时，局部环境所起的作用。
