Tuning the luminescence lifetimes of ruthenium(ii) polypyridine complexes and its application in luminescent oxygen sensing
作者:Shaomin Ji、Wanhua Wu、Wenting Wu、Peng Song、Keli Han、Zhonggang Wang、Shasha Liu、Huimin Guo、Jianzhang Zhao
DOI:10.1039/b916468e
日期:——
Ru(Phen)(bpy)2 (1) and its new derivatives (2–5) with pyrenyl or ethynylated pyrene and phenyl units appended to the 3-position of the phenanthroline (Phen) ligand were prepared and these complexes generate long-lived room temperature phosphorescence in the red and near IR range (600–800 nm). The photophysical properties of these complexes were investigated by UV-Vis absorption, luminescence emission, transient absorption spectra and DFT/TDDFT calculations. We found the luminescence lifetime (τ)can be drastically extended by ligand modification (increased up to 140-fold), e.g. τ = 58.4 μs for complex 3 (with pyrenyl ethynylene appendents) was found, compared to τ = 0.4 μs for the reference complex 1. Ethynylated phenyl appendents alter the τ also (complex 2, τ = 2.4 μs). With pyrenyl appendents (4 and 5), lifetimes of 2.5 μs and 9.2 μs were observed. We proposed three different mechanisms for the lifetime extension of 2, 3, 4 and 5. For 2, the stabilization of the 3MLCT state by π-conjugation is responsible for the extension of the lifetime. For 3, the emissive state was assigned as an intra-ligand (IL) long-lived 3π–π* state (3IL/3LLCT, intraligand or ligand-to-ligand charge transfer), whereas a C–C single bond linker results in a triplet state equilibrium between 3MLCT state and the pyrene localized 3π–π* triplet state (3IL, e.g.4 and 5). DFT/TDDFT calculations support the assignment of the emissive states. The effects of the lifetime extension on the oxygen sensing properties of these complexes were studied in both solution and polymer films. With tuning the emissive states, and thus extension of the luminescence lifetimes, the luminescent O2 sensing sensitivity of the complexes can be improved by ca. 77-fold in solution (I0/I100 = 1438 for complex 3, vs. I0/I100 = 18.5 for complex 1). In IMPES-C polymer films, the apparent quenching constant KSVapp is improved by 150-fold from 0.0023 Torr−1 (complex 1) to 0.35 Torr−1 (complex 3). The KSVapp value of complex 3 is even higher than that of PtOEP under similar conditions (0.15 Torr−1).
研究人员制备了 Ru(Phen)(bpy)2 (1) 及其新衍生物 (2-5),在菲罗啉 (Phen) 配体的 3 位附加了芘或乙炔化芘和苯基单元,这些配合物在红色和近红外范围(600-800 纳米)产生长效室温磷光。我们通过紫外可见吸收、发光发射、瞬态吸收光谱和 DFT/TDDFT 计算研究了这些配合物的光物理特性。我们发现,配体修饰可大幅延长发光寿命(τ)(最多可增加 140 倍),例如,与参考配合物 1 的 τ = 0.4 μs 相比,τ = 58.4 μs 适用于配合物 3(具有芘基乙炔基附属物)。乙炔化苯基附属物也会改变 τ (络合物 2,τ = 2.4 μs)。对于芘基附属物(4 和 5),观察到的寿命分别为 2.5 μs 和 9.2 μs。我们为 2、3、4 和 5 的寿命延长提出了三种不同的机制。对 2 而言,π-共轭对 3MLCT 状态的稳定是寿命延长的原因。而 C-C 单键连接体则导致 3MLCT 状态和芘局部 3π-π* 三重态(3IL,例如 4 和 5)之间的三重态平衡。DFT/TDDFT 计算支持发射态的分配。研究人员在溶液和聚合物薄膜中研究了寿命延长对这些复合物氧传感特性的影响。通过调整发射态从而延长发光寿命,这些复合物在溶液中的氧气传感灵敏度提高了约 77 倍(复合物 3 的 I0/I100 = 1438,而复合物 1 的 I0/I100 = 18.5)。在 IMPES-C 聚合物薄膜中,表观淬火常数 KSVapp 从 0.0023 托-1(复合物 1)提高到 0.35 托-1(复合物 3),提高了 150 倍。复合物 3 的 KSVapp 值甚至高于类似条件下 PtOEP 的 KSVapp 值(0.15 托-1)。