Hybrid CO₂-reduction photocatalysts based on Re(bpy)(CO)₃Cl, where bpy is 2,2′-bipyridine, were synthesized in order to investigate the effect of different ligand derivatization strategies on photochemical properties of the hybrid Re(I) systems. Derivatization of the bpy ligand was carried out at the 4,4′- and 5,5′-positions with electron-withdrawing amide groups. The derivatized ligands were grafted on mesoporous silica via a dipodal silane coupling agent and were further coordinated with Re(I). The synthesized hybrid photocatalysts were studied using spectroscopic techniques, including UV–visible, in situ infrared and electron paramagnetic resonance (EPR) spectroscopy, and tested in photochemical CO₂ reduction. An interesting light-induced color change was observed for the hybrid photocatalyst involving derivatization of the bpy ligand at the 5,5′-positions. Combined UV–visible and EPR studies indicated that in the reduced form of this hybrid photocatalyst electron density was more localized on the bpy ligand than on the Re(I) center. Further studies with in situ infrared spectroscopy demonstrated possible formation of a carbonate-bridged binuclear Re(I) species on this hybrid photocatalyst. Our results are particularly relevant to developing new molecular and hybrid photocatalytic systems which involve extensive derivatization of coordinating ligands with functional groups for improved solar energy conversion.

中文翻译：

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不同位置配体衍生化对杂化Re（I）光催化剂光化学性质的影响

合成了基于Re（bpy）（CO）₃ Cl的杂化CO ₂还原光催化剂，其中bpy为2,2'-联吡啶，以研究不同配体衍生化策略对杂化Re（I）的光化学性质的影响）系统。在具有吸电子酰胺基团的4,4'-和5,5'-位进行bpy配体的衍生。衍生的配体通过二足硅烷偶联剂接枝到中孔二氧化硅上，并与Re（I）进一步配位。使用光谱技术研究了合成的杂化光催化剂，包括紫外可见光谱，原位红外光谱和电子顺磁共振（EPR）光谱，并在光化学CO _2中进行了测试。减少。对于杂化光催化剂，观察到一个有趣的光致颜色变化，该变化涉及bpy配体在5,5'-位置的衍生化。结合的紫外线可见光和EPR研究表明，在这种混合光催化剂的还原形式中，电子密度更多地位于bpy配体上而不是Re（I）中心上。原位红外光谱的进一步研究表明，在这种杂化光催化剂上可能形成碳酸盐桥连的双核Re（I）物种。我们的结果与开发新的分子和杂化光催化体系特别相关，该体系涉及广泛配位的配体与官能团的衍生化，以改善太阳能的转化。