Department of Chemistry and Biochemistry , Ohio University , Athens , Ohio 45701 , United States.
Inorg Chem. 2018 Sep 17;57(18):11616-11625. doi: 10.1021/acs.inorgchem.8b01759. Epub 2018 Aug 30.
Two diimine-bridged Ru(II),Mn(I) complexes with a [(bpy)Ru(BL)Mn(CO)Br] architecture, where bpy = 2,2'-bipyridine and BL = 2,3-bis(2-pyridyl)pyrazine (dpp; Ru(dpp)Mn) or 2,2'-bipyrimidine (bpm; Ru(bpm)Mn), were designed to both dissociate multiple equivalents of CO and produce O when irradiated with visible light. Analysis of the complexes by Fourier transform infrared (FTIR) spectroscopy and cyclic voltammetry suggest a stronger π-accepting ability for bpm compared to that of dpp. Both complexes absorb light throughout the UV and visible regions with lowest energy absorption bands comprising overlapping Ru(dπ)→BL(π*) and Mn(dπ)→BL(π*) singlet metal-to-ligand charge transfer (MLCT) and Br(p)→dpp(π*) singlet halide-to-ligand charge transfer (XLCT) transitions. This lowest energy band is centered at 510 nm (ε = 12 000 Mcm) for Ru(dpp)Mn and 553 nm (ε = 3240 Mcm) for Ru(bpm)Mn, and the absorption band extends to nearly 700 nm in each case. Irradiation with visible light (both 470 and 627 nm) releases all three CO ligands, as observed by a combination of UV-vis, FTIR, and gas chromatography. The exchange of the first CO ligand with a solvent molecule occurs more efficiently for Ru(dpp)Mn (Φ = 0.22 ± 0.03 in HO; 0.37 ± 0.06 in CHCN) than for Ru(bpm)Mn (Φ = 0.049 ± 0.008 in HO and 0.16 ± 0.03 in CHCN), and the CO dissociation efficiency is unaffected by irradiation wavelength. The differences between Ru(dpp)Mn and Ru(bpm)Mn are proposed to result from the variation in electron density distribution across each formally reduced BL in the Mn(dπ)→BL(π*) MLCT excited state based on the nature of BL. Exhaustive photolysis causes the decomplexation of oxidized Mn(II), and the resulting [(bpy)Ru(BL)] complexes produce O with quantum yields (Φ) of 0.37 ± 0.03 and 0.16 ± 0.01 for Ru(dpp) and Ru(bpm), respectively, with 460 nm irradiation. This bimetallic architecture presents the opportunity to use visible light to codeliver both CO and O, both of which have biological relevance in photoactivated therapeutics, with spatiotemporal control.
设计了两个二亚胺桥联的 Ru(II),Mn(I) 配合物，具有 [(bpy)Ru(BL)Mn(CO)Br] 结构，其中 bpy = 2,2'-联吡啶，BL = 2,3-双(2-吡啶基)吡嗪 (dpp; Ru(dpp)Mn) 或 2,2'-联嘧啶 (bpm; Ru(bpm)Mn)，可在可见光照射下解离多个 CO 当量并产生 O。傅里叶变换红外 (FTIR) 光谱和循环伏安法分析表明，bpm 比 dpp 具有更强的 π 接受能力。两个配合物在整个 UV 和可见区域吸收光，最低能量吸收带包括重叠的 Ru(dπ)→BL(π*) 和 Mn(dπ)→BL(π*) 单重金属-配体电荷转移 (MLCT) 和 Br(p)→dpp(π*) 单重卤化物-配体电荷转移 (XLCT) 跃迁。该最低能量带位于 510 nm（ε = 12 000 Mcm），对于 Ru(dpp)Mn，位于 553 nm（ε = 3240 Mcm），对于 Ru(bpm)Mn，吸收带在每种情况下延伸至近 700 nm。用可见光（470 和 627 nm）照射可释放出所有三个 CO 配体，这可以通过紫外可见、FTIR 和气相色谱的组合来观察。Ru(dpp)Mn 中与溶剂分子交换第一个 CO 配体的效率更高（Φ = 0.22 ± 0.03 在 HO 中；0.37 ± 0.06 在 CHCN 中），而 Ru(bpm)Mn 的效率更低（Φ = 0.049 ± 0.008 在 HO 中和 0.16 ± 0.03 在 CHCN 中），并且 CO 解离效率不受照射波长的影响。Ru(dpp)Mn 和 Ru(bpm)Mn 之间的差异据推测是基于 BL 的性质，在 Mn(dπ)→BL(π*) MLCT 激发态中，每个形式还原的 BL 上的电子密度分布的变化所致。彻底的光解导致氧化的 Mn(II)脱配合物，所得 [(bpy)Ru(BL)] 配合物在 460 nm 照射下产生 O，量子产率 (Φ) 分别为 0.37 ± 0.03 和 0.16 ± 0.01，用于 Ru(dpp) 和 Ru(bpm)。这种双金属结构提供了使用可见光共输送 CO 和 O 的机会，这两者在光激活治疗中都具有生物学相关性，具有时空控制。
