Schüssler L, Israil R G E, Hütchen P, Thiel W R, Diller R, Riehn C
Department of Physics, Technische Universität Kaiserslautern (TUK), Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany.
Department of Chemistry, Technische Universität Kaiserslautern (TUK), Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany.
Phys Chem Chem Phys. 2023 Feb 8;25(6):4899-4914. doi: 10.1039/d2cp03765c.
[Ru(bipyridine)(nicotinamide)] (1) and its monoaqua-complex [Ru(bipyridine)(nicotinamide)(HO)] (2) were spectroscopically studied for the first time in the gas phase by static and time resolved UV photodissociation spectroscopy, observing nicotinamide and HO ligand dissociation for 1 and 2, respectively. Both processes and their ultrafast dynamics were investigated in parallel by transient absorption spectroscopy in aqueous solution. The latter data were newly acquired for the long-wavelength MLCT band excitation of 1 and provide novel ultrafast ligand dissociation results for 2, confirming the gas phase results, , exclusive HO cleavage over nicotinamide loss. Similar apparent time constants in the sub-ps and few ps ranges were obtained for 1 in both phases, whereas a larger time constant of two hundreds of ps for the ground state recovery was observed exclusively in the solution phase. Our reaction scheme accounts for faster dissociation dynamics in the gas phase by energetical lowering of the MC the MLCT states by lack of solvent stabilization of the latter. Based on the apparent time constants, we favour, for the solution dynamics, a fast bimodal vibrational deactivation in the MLCT/MC manifolds and a slow dissociation obfuscated by the ground state recovery. This is substantiated by a similar reaction scheme proposed for the ultrafast dynamics of 2, resulting in a new assignment for transient absorption features with > 550 nm to the MC manifold, and a common kinetic description for 1 and 2. Computations at the TD-DFT/cc-PVTZ/MDF28 level support our spectroscopic findings and the suggested deactivation pathways.
首次通过静态和时间分辨紫外光解离光谱在气相中对[Ru(联吡啶)(烟酰胺)] (1)及其单水络合物[Ru(联吡啶)(烟酰胺)(H₂O)] (2)进行了光谱研究，分别观察到1和2的烟酰胺和H₂O配体解离。通过水溶液中的瞬态吸收光谱并行研究了这两个过程及其超快动力学。后者的数据是新获得的，用于1的长波长MLCT带激发，并为2提供了新的超快配体解离结果，证实了气相结果，即优先发生H₂O裂解而非烟酰胺损失。在两个相中，1在亚皮秒和几皮秒范围内获得了相似的表观时间常数，而仅在溶液相中观察到基态恢复的较大时间常数为几百皮秒。我们的反应方案解释了气相中更快的解离动力学，这是由于MC和MLCT态的能量降低，因为后者缺乏溶剂稳定作用。基于表观时间常数，对于溶液动力学，我们倾向于MLCT/MC流形中的快速双峰振动失活和被基态恢复掩盖的缓慢解离。这通过为2的超快动力学提出的类似反应方案得到证实，该方案导致对波长大于550 nm的瞬态吸收特征重新分配到MC流形，并对1和2进行了共同的动力学描述。在TD-DFT/cc-PVTZ/MDF28水平上的计算支持了我们的光谱研究结果和建议的失活途径。
