Université Joseph Fourier Grenoble 1/CNRS, Département de Chimie Moléculaire, UMR-5250, Laboratoire de Chimie Inorganique Rédox, Institut de Chimie Moléculaire de Grenoble FR-CNRS-2607, BP-53, 38041 Grenoble Cedex 9, France.
Chemistry. 2011 Apr 4;17(15):4313-22. doi: 10.1002/chem.201003098. Epub 2011 Mar 4.
Optical excitation in the visible region of trans-(Cl)-[Os(bpy)(CO)(2)Cl(2)] (bpy=2,2'-bipyridine; C1) and trans-(Cl)-[Os(dmbpy)(CO)(2)Cl(2)] (dmbpy=4,4'-dimethyl 2,2'-bipyridine; C2) is known to induce the common CO dissociation reaction. However, the quantum yield of the reactions is less than 0.15, although C1 and C2 display pronounced photoluminescence in the visible region at room temperature with a lifetime of few tens of nanoseconds. Taking into account the characteristics of their emitting state, we have investigated the capability of C1 and C2 to act as a photosensitiser in redox reactions in different solvents (MeCN, PrCN and DMF). The efficient oxidation and reduction of both complexes under continuous irradiation in the presence of a sacrificial electron acceptor or donor is reported here. The photo-induced transformations and the nature of the resulting compounds were analysed by UV/Vis and IR spectroscopies and cyclic voltammetry. Photo-induced oxidation of C1 and C2 leads to the corresponding monocarbonyl oxidised species, whereas photo-induced reduction under argon leads mainly to the formation of the corresponding Os-bonded molecular wires P1 and P2 after exchange of two electrons associated with the loss of two chloro ligands. The chemical yield of the latter reaction (around 65%) becomes quantitative by adding Ru(bpy)(3) as an external redox photosensitiser. This behaviour has been used to photocatalyse the two electron, two proton conversion of CO(2) to CO. Turnover numbers (TON) of 11.5 and 19.5 have been obtained respectively for C1 and C2 after 4.5 h of irradiation under CO(2) in DMF with triethanolamine as the electron donor. TON can be slightly increased by adding Ru(bpy)(3) to the solution.
在可见区域中，顺式-(Cl)-[Os(bpy)(CO)(2)Cl(2)]（bpy=2,2'-联吡啶；C1）和顺式-(Cl)-[Os(dmbpy)(CO)(2)Cl(2)]（dmbpy=4,4'-二甲基 2,2'-联吡啶；C2）的光激发已知会诱导常见的 CO 解离反应。然而，尽管 C1 和 C2 在室温下在可见区域显示出明显的光致发光，寿命为数十纳秒，但反应的量子产率小于 0.15。考虑到它们发射态的特点，我们研究了 C1 和 C2 在不同溶剂（MeCN、PrCN 和 DMF）中作为氧化还原反应的光引发剂的能力。本文报道了在牺牲电子给体或受体存在下，这两种配合物在连续辐照下的有效氧化和还原。通过紫外/可见和红外光谱以及循环伏安法分析了光诱导转化和所得化合物的性质。C1 和 C2 的光诱导氧化导致相应的单羰基氧化物种，而在氩气下的光诱导还原主要导致在与两个氯配体的损失相关的两个电子的交换后形成相应的 Os 键合分子线 P1 和 P2。通过添加 Ru(bpy)(3) 作为外部氧化还原光引发剂，后者反应（约 65%）的化学产率变为定量。这种行为已用于光催化 CO2 的两电子、两质子转化为 CO。在 DMF 中用三乙醇胺作为电子供体，在 CO2 下照射 4.5 小时后，C1 和 C2 的转化率（TON）分别为 11.5 和 19.5。通过向溶液中添加 Ru(bpy)(3)，TON 可以略有增加。
