AbstractEarth‐abundant photosensitizers are highly sought after for light‐mediated applications, such as photoredox catalysis, depollution and energy conversion schemes. Homoleptic and heteroleptic copper(I) complexes are promising candidates in this field, as copper is abundant and the corresponding complexes are easily obtained in smooth conditions. However, some heteroleptic copper(I) complexes suffer from low (photo)stability that leads to the gradual formation of the corresponding homoleptic complex. Such degradation pathways are detrimental, especially when recyclability is desired. This study reports a novel approach for the heterogenization of homoleptic and heteroleptic Cu complexes on silica nanoparticles. In both cases, the photophysical properties upon surface immobilization were only slightly affected. Excited‐state quenching with aryl diazonium derivatives occurred efficiently (108–1010 M−1 s−1) with heterogeneous and homogeneous photosensitizers. Moderate but almost identical yields were obtained for the α‐arylation of enol acetate using the homoleptic complex in homogeneous or heterogeneous conditions. Importantly, the silica‐supported photocatalysts were recycled with moderate loss in photoactivity over multiple experiments. Transient absorption spectroscopy confirmed that excited‐state electron transfer occurred from the homogeneous and heterogeneous homoleptic copper(I) complexes to aryl diazonium derivatives, generating the corresponding copper(II) center that persisted for several hundreds of microseconds, compatible with photoredox catalysis applications.
摘要 地球上丰富的光敏剂在以光为媒介的应用中备受青睐,如光氧化催化、去污染和能量转换方案。同性和异性
铜(I)络合物是这一领域很有希望的候选物质,因为
铜的储量丰富,而且相应的络合物很容易在顺利的条件下获得。然而,一些杂色
铜(I)络合物的(光)稳定性较低,导致相应的同色络合物逐渐形成。这种降解途径是有害的,尤其是在需要可回收性的情况下。本研究报告了一种在
二氧化硅纳米颗粒上对同象和异象
铜络合物进行异质化的新方法。在这两种情况下,表面固定后的光物理特性只受到轻微影响。芳基重氮衍
生物的激发态淬灭在异质和均质光敏剂上都能有效发生(108-1010 M-1 s-1)。在均相或异相条件下,使用均相络合物对
乙酸烯醇进行α-芳香化反应,可获得中等但几乎相同的产率。重要的是,在多次实验中,
二氧化硅支撑的光催化剂可循环使用,光活性损失不大。瞬态吸收光谱证实,激发态电子从均相和异相的均质
铜(I)络合物转移到芳基重氮衍
生物上,产生相应的
铜(II)中心,并持续数百微秒,符合光氧化催化应用的要求。