Possamai Giorgia, Menna Enzo, Maggini Michele, Carano Maurizio, Marcaccio Massimo, Paolucci Francesco, Guldi Dirk M, Swartz Angela
Unità INSTM, sezione di Padova, Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padua, Italy.
Photochem Photobiol Sci. 2006 Dec;5(12):1154-64. doi: 10.1039/b610811c. Epub 2006 Sep 28.
A cyclopropanation reaction has been used to prepare two methanofullerenes bearing a 2,2'-bipyridine () or pyridine () ligand separated from the fullerene through an oxyethylene macrocyclic spacer. Derivatives and were, in turn, employed to synthesize two fullerene-based ruthenium(ii) and rhenium(i) donor-acceptor dyads whose molecular structure was confirmed by (1)H NMR, (13)C NMR and exact mass determination. The UV-Vis spectrum of the dyads is the superimposition of those of appropriate model systems, indicating that ground-state electronic interactions between the constituent chromophores, in solution, are negligible, in line also with the electrochemical results. The complex voltammetric pattern was characterized by the superimposition of signals attributed to one moiety or another without significant shifts with respect to their models. Furthermore, both species undergo partial chemical degradation in the time scale of cyclic voltammetry upon their multiple reduction. Photophysical properties of and , namely, excited state interactions between the ruthenium(ii) or rhenium(i) complexes and [60]fullerene have been investigated by steady-state and time-resolved UV-Vis-NIR luminescence spectroscopy that was complemented by nanosecond laser flash photolysis in CH(2)Cl(2) solutions. All experimental findings were set into relation with the corresponding reference compounds. More precisely, excitation of the metal complexes in and gives rise to a notable steady-state and time-resolved luminescence quenching of both metal to ligand charge transfer states (i.e., Ru(bpy)(3) and (bpy)Re(CO)(3)(py)). Conclusive evidence about the nature of the photoproducts came from nanosecond laser flash photolysis. In these experiments, only the long-lived and oxygen-sensitive [60]fullerene triplets were detected. Two pathways are envisioned for this [60]fullerene triplet formation. Firstly, intramolecular transduction of the triplet excited state energy evolving from the photoexcited metal complexes. Secondly, intersystem crossing of directly excited [60]fullerene.
环丙烷化反应已被用于制备两种含有2,2'-联吡啶（ ）或吡啶（ ）配体的甲烷富勒烯，这些配体通过氧乙烯大环间隔基与富勒烯分离。衍生物 和 进而被用于合成两种基于富勒烯的钌（II）和铼（I）供体-受体二元化合物，其分子结构通过（1）H NMR、（13）C NMR和精确质量测定得以确认。二元化合物的紫外-可见光谱是适当模型体系光谱的叠加，表明在溶液中，组成发色团之间的基态电子相互作用可忽略不计，这也与电化学结果一致。复杂的伏安图的特征是归因于一个或另一个部分的信号叠加，相对于其模型没有明显的位移。此外，在循环伏安法的时间尺度上，这两种物质在多次还原时都会发生部分化学降解。通过稳态和时间分辨紫外-可见-近红外发光光谱研究了 和 的光物理性质，即在二氯甲烷溶液中通过纳秒激光闪光光解进行补充，研究了钌（II）或铼（I）配合物与[60]富勒烯之间的激发态相互作用。所有实验结果都与相应的参考化合物相关。更确切地说， 和 中金属配合物的激发导致金属到配体电荷转移态（即[Ru(bpy)3]2+和[(bpy)Re(CO)3(py)]+）的显著稳态和时间分辨发光猝灭。关于光产物性质的确凿证据来自纳秒激光闪光光解。在这些实验中，仅检测到了长寿命且对氧敏感的[60]富勒烯三线态。对于这种[60]富勒烯三线态的形成设想了两条途径。首先，从光激发的金属配合物演化而来的三线态激发态能量的分子内转导。其次，直接激发的[60]富勒烯的系间窜越。
