A recently reported ruthenium(II) complex bearing an extended dipyridophenazine ligand exhibits unusual long-lived dual emission at room temperature. In this study, the effect of the introduction of a methyl protecting group to the imidazole moiety of this ligand (L1, 11-methyl-11H-imidazo[4,5-i]dipyrido[3,2-a:2′,3′-c]phenazine) on the photophysics of the respective ruthenium(II) complex [(tbbpy)₂Ru(L1)]²⁺ (C1) is demonstrated by means of electrochemistry, UV/vis absorption and emission spectroscopy, as well as emission lifetime measurements, and transient absorption spectroscopy on the nanosecond time scale. At room temperature, C1 shows dual emission both in aprotic and in protic solvents with time constants of 1.1/34.2 and 1.2/8.4 μs, respectively. These lifetimes are assigned to the emission from ³MLCT and ³LC states. The introduction of the methyl group increases the lifetime of the ³LC state in C1 almost by a factor of 2 in acetonitrile solution compared to the previously reported compound. Accordingly, the newly introduced methyl group is described as a protecting group for the imidazole moiety of the heterocyclic ligand, which enables prolonged lifetimes of the dual emissive complex in protic solvents. The stabilization of the electronic structure is further underlined by the enhanced stability toward electrochemical reduction as evidenced by cyclic voltammetry.

中文翻译：

---

在非质子和质子溶剂中延长双发光钌双吡啶并吩嗪型复合物的发光寿命

最近报道的带有扩展的双吡啶并吩嗪配体的钌 (II) 配合物在室温下表现出不寻常的长寿命双发射。在本研究中，在该配体的咪唑部分引入甲基保护基团 ( L1 , 11-methyl-11 H - imidazo[4,5- i ]dipyrido[3,2- a :2', 3'- c ]吩嗪) 对各个钌 (II) 配合物 [(tbbpy) ₂ Ru( L1 )] ²⁺ ( C1) 是通过电化学、紫外/可见吸收和发射光谱、发射寿命测量和纳秒时间尺度上的瞬态吸收光谱来证明的。在室温下，C1在非质子和质子溶剂中均显示出双发射，时间常数分别为 1.1/34.2 和 1.2/8.4 μs。这些寿命分配给来自^{3 个}MLCT 和^{3 个}LC 状态的发射。甲基的引入增加了C1 中³ LC 状态的寿命与之前报道的化合物相比，在乙腈溶液中几乎增加了 2 倍。因此，新引入的甲基被描述为杂环配体的咪唑部分的保护基团，这使得双发射复合物在质子溶剂中的寿命延长。如循环伏安法所证明的，对电化学还原的稳定性增强进一步强调了电子结构的稳定性。