Matlachowski Corinna, Schwalbe Matthias
Institute of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-St. 2, 12489 Berlin, Germany.
Dalton Trans. 2015 Apr 14;44(14):6480-9. doi: 10.1039/c4dt03846k.
We here present a comprehensive study on the light-induced catalytic CO2 reduction employing a number of mono- and dinuclear complexes with a phenanthroline-extended tetramesityl porphyrin ligand (). A stepwise synthesis of heterodinuclear complexes is possible because the phenanthroline moiety of the ligand can selectively coordinate a second metal center, e.g. Ru(tbbpy)2(2+) fragment, while any other metal can reside in the porphyrin cavity. We expanded our former studies to cobalt and iron compounds and synthesized the complexes , and , . Thorough catalytic investigation on the light-driven CO2 reduction of all compounds (M = 2H, Cu, Pd, Co, FeCl) was performed in a DMF solution in the presence of triethylamine (TEA) as a sacrificial electron donor. A very surprising wavelength dependence of the catalytic performance was observed. Turnover numbers (TONs) of CO were quantified and showed that redox active metals (i.e.M = Co and FeCl) in the porphyrin cavity caused the highest catalytic activity. After 24 hours of illumination with light λ > 305 nm reached a TONCO of 11.4 with our experimental setup without showing much decomposition. This value is twice as high as the TONCO determined for CoTPP (5.8) under the same conditions, which represented the most active porphyrinic system so far for photocatalytic CO2 reduction.
我们在此展示了一项关于光诱导催化二氧化碳还原的综合研究，该研究采用了多种带有菲咯啉扩展四（对甲基苯基）卟啉配体（）的单核和双核配合物。异双核配合物的逐步合成是可行的，因为配体的菲咯啉部分可以选择性地配位第二个金属中心，例如Ru(tbbpy)2(2+)片段，而任何其他金属可以位于卟啉腔内。我们将之前的研究扩展到钴和铁化合物，并合成了配合物、和。在作为牺牲电子供体的三乙胺（TEA）存在下，于DMF溶液中对所有化合物（M = 2H、Cu、Pd、Co、FeCl）的光驱动二氧化碳还原进行了全面的催化研究。观察到了催化性能非常令人惊讶的波长依赖性。对CO的周转数（TONs）进行了量化，结果表明卟啉腔内的氧化还原活性金属（即M = Co和FeCl）导致了最高的催化活性。在λ > 305 nm的光照射24小时后，在我们的实验装置中达到了11.4的TONCO，且没有显示出太多分解。该值是在相同条件下测定的CoTPP（5.8）的TONCO的两倍，CoTPP是迄今为止光催化二氧化碳还原中最具活性的卟啉体系。
