Frin Karina P Morelli, de Almeida Rafael M
Federal University of ABC - UFABC, Av. dos Estados 5001, Santo André, 09210-170, SP, Brazil.
Photochem Photobiol Sci. 2017 Aug 9;16(8):1230-1237. doi: 10.1039/c7pp00092h.
Mono-nuclear fac-[Re(CO)(phphen)(4,4'-bpy)] and di-nuclear [(phphen)(CO)Re(4,4'-bpy)Re(phphen)(CO)] complexes, phphen = 4,7-diphenyl-1,10-phenanthroline and 4,4'-bpy = 4,4'-bipyridine, were synthesized and characterized by H NMR, UV-visible and FT-IR spectroscopy. Also, their photophysical properties were investigated using steady-state and time-resolved emission spectroscopy. Both complexes showed UV absorption assigned to intraligand, IL, and metal-to-ligand charge transfer, MLCT, transitions, and typical MLCT emission (ϕ = 0.360 and τ = 3.81 μs; ϕ = 0.177 and τ = 1.90 μs for mono- and di-nuclear, respectively). Additionally, the luminescence of these complexes is quenched by hydroquinone with approximately 4 × 10 L mol s rate constant for the bimolecular excited state, k. The Stern-Volmer constants, K, determined by the emission intensity and lifetime showed excellent correlation, which is indicative of the dynamic quenching. The similarity of the bimolecular rate constants between the two complexes implies that the photoinduced electron transfer is the main pathway with a very small (or no) influence of the proton transfer step. The results provide additional insight into the role of the protonable nitrogen atom in the photophysical properties of rhenium(i) complexes, using a dyad architecture.
单核配合物 fac-[Re(CO)(phphen)(4,4'-bpy)] 和双核配合物 [(phphen)(CO)Re(4,4'-bpy)Re(phphen)(CO)]（其中 phphen = 4,7-二苯基-1,10-菲咯啉，4,4'-bpy = 4,4'-联吡啶）被合成出来，并通过核磁共振氢谱、紫外可见光谱和傅里叶变换红外光谱进行了表征。此外，还使用稳态和时间分辨发射光谱对它们的光物理性质进行了研究。两种配合物都显示出归属于配体内（IL）和金属到配体电荷转移（MLCT）跃迁的紫外吸收，以及典型的 MLCT 发射（单核配合物的 ϕ = 0.360，τ = 3.81 μs；双核配合物的 ϕ = 0.177，τ = 1.90 μs）。此外，对苯二酚会猝灭这些配合物的发光，双分子激发态猝灭速率常数 k 约为 4 × 10 L mol⁻¹ s⁻¹。通过发射强度和寿命测定的斯特恩 - 沃尔默常数 K 显示出良好的相关性，这表明是动态猝灭。两种配合物双分子速率常数的相似性意味着光诱导电子转移是主要途径，质子转移步骤的影响非常小（或没有）。这些结果使用二元结构，为可质子化氮原子在铼（I）配合物光物理性质中的作用提供了更多见解。
