Tomar Monika, Thapper Anders, Orthaber Andreas, Borbas K Eszter
Department of Chemistry, Ångström Laboratory, Uppsala University, 75120 Uppsala, Sweden.
Inorg Chem. 2025 Jan 13;64(1):594-605. doi: 10.1021/acs.inorgchem.4c03926. Epub 2024 Dec 23.
The reduction of stable trivalent lanthanide species (Ln(III)) by the excited states of organic chromophores is the basis of photocatalytic divalent lanthanide-mediated reduction reactions. While indirect evidence of the photochemical formation of the reactive Ln(II) species is abundant, direct spectroscopic evidence of their presence is scarce. Here, nine chromophores with absorptions covering the near UV and visible ranges were systematically investigated in the presence of Ln(III) ions to evaluate their ability to reduce Eu(III) upon excitation with visible light to the catalytically active Eu(II) species. Irradiated mixtures of Eu(III) and the chromophores were characterized using UV-vis absorption and emission and EPR spectroscopy. Several of the chromophore-Eu(III) combinations were competent photocatalysts in the presence of N,N-diisopropylethylamine or Zn terminal reductants. These results demonstrate that a variety of visible-absorbing chromophores can efficiently generate reactive Eu(II) from Eu(III) to catalyze Ln(II)-mediated reduction reactions.
有机发色团的激发态对稳定的三价镧系元素物种（Ln(III)）的还原作用是光催化二价镧系元素介导的还原反应的基础。虽然关于反应性Ln(II)物种光化学形成的间接证据很多，但它们存在的直接光谱证据却很少。在这里，系统研究了九种吸收覆盖近紫外和可见光范围的发色团在Ln(III)离子存在下的情况，以评估它们在用可见光激发时将Eu(III)还原为具有催化活性的Eu(II)物种的能力。使用紫外可见吸收、发射和电子顺磁共振光谱对Eu(III)与发色团的辐照混合物进行了表征。在N,N-二异丙基乙胺或锌终端还原剂存在下，几种发色团-Eu(III)组合是有效的光催化剂。这些结果表明，多种可见光吸收发色团可以有效地从Eu(III)生成反应性Eu(II)，以催化Ln(II)介导的还原反应。
