当前位置: X-MOL 学术J. Am. Chem. Soc. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Visible Light Driven Bromide Oxidation and Ligand Substitution Photochemistry of a Ru Diimine Complex
Journal of the American Chemical Society ( IF 15.0 ) Pub Date : 2018-03-29 , DOI: 10.1021/jacs.8b00944
Guocan Li 1 , Matthew D. Brady 1 , Gerald J. Meyer 1
Affiliation  

The complex [Ru(deeb)(bpz)2]2+ (RuBPZ2+, deeb = 4,4'-diethylester-2,2'-bipyridine, bpz = 2,2'-bipyrazine) forms a single ion pair with bromide, [RuBPZ2+, Br-]+, with Keq = 8400 ± 200 M-1 in acetone. The RuBPZ2+ displayed photoluminescence (PL) at room temperature with a lifetime of 1.75 μs. The addition of bromide to a RuBPZ2+ acetone solution led to significant PL quenching and Stern-Volmer plots showed upward curvature. Time-resolved PL measurements identified two excited state quenching pathways, static and dynamic, which were operative toward [RuBPZ2+, Br-]+ and free RuBPZ2+, respectively. The single ion-pair [RuBPZ2+, Br-]+* had a lifetime of 45 ± 5 ns, consistent with an electron transfer rate constant, ket = (2.2 ± 0.3) × 107 s-1. In contrast, RuBPZ2+* was dynamically quenched by bromide with a quenching rate constant, kq = (8.1 ± 0.1) × 1010 M-1 s-1. Nanosecond transient absorption revealed that both the static and dynamic pathways yielded RuBPZ+ and Br2•- products that underwent recombination to regenerate the ground state with a second-order rate constant, kcr = (2.3 ± 0.5) × 1010 M-1 s-1. Kinetic analysis revealed that RuBPZ+ was a primary photoproduct, while Br2•- was secondary product formed by the reaction of a Br• with Br-, k = (1.1 ± 0.2) × 1010 M-1 s-1. Marcus theory afforded an estimate of the formal reduction potential for E0(Br•/-) in acetone, 1.42 V vs NHE. A 1H NMR analysis indicated that the ion-paired bromide was preferentially situated close to the RuII center. Prolonged steady state photolysis of RuBPZ2+ and bromide yielded two ligand-substituted photoproducts, cis- and trans-Ru(deeb)(bpz)Br2. A photochemical intermediate, proposed to be [Ru(deeb)(bpz)(κ1-bpz)(Br)]+, was found to absorb a second photon to yield cis- and trans-Ru(deeb)(bpz)Br2 photoproducts.

中文翻译:

Ru二亚胺配合物的可见光驱动溴氧化和配体取代光化学

复合物 [Ru(deeb)(bpz)2]2+ (RuBPZ2+, deeb = 4,4'-diethylester-2,2'-bipyridine, bpz = 2,2'-bipyrazine) 与溴化物形成单离子对, [RuBPZ2+, Br-]+,丙酮中的 Keq = 8400 ± 200 M-1。RuBPZ2+ 在室温下显示出光致发光 (PL),寿命为 1.75 μs。向 RuBPZ2+ 丙酮溶液中添加溴化物导致显着的 PL​​ 猝灭,Stern-Volmer 图显示向上弯曲。时间分辨 PL 测量确定了两种激发态猝灭途径,静态和动态,分别对 [RuBPZ2+, Br-]+ 和游离 RuBPZ2+ 起作用。单个离子对 [RuBPZ2+, Br-]+* 的寿命为 45 ± 5 ns,与电子转移速率常数 ket = (2.2 ± 0.3) × 107 s-1 一致。相比之下,RuBPZ2+* 被溴化物动态猝灭,猝灭速率常数 kq = (8. 1 ± 0.1) × 1010 M-1 s-1。纳秒瞬态吸收表明,静态和动态途径均产生 RuBPZ+ 和 Br2•- 产物,这些产物经过重组以二阶速率常数 kcr = (2.3 ± 0.5) × 1010 M-1 s-1 重新生成基态。动力学分析表明,RuBPZ+ 是初级光产物,而 Br2•- 是 Br• 与 Br- 反应形成的次级产物,k = (1.1 ± 0.2) × 1010 M-1 s-1。Marcus 理论提供了对 E0(Br•/-) 在丙酮中的正式还原电位的估计,1.42 V vs NHE。1H NMR 分析表明离子对溴化物优先位于靠近 RuII 中心的位置。RuBPZ2+ 和溴化物的长时间稳态光解产生两种配体取代的光产物,顺式和反式 Ru(deeb)(bpz)Br2。一种光化学中间体,
更新日期:2018-03-29
down
wechat
bug