Kronenberger Sandra, Naumann Robert, Förster Christoph, East Nathan R, Klett Jan, Heinze Katja
Department of Chemistry, Johannes Gutenberg University Mainz, Mainz, Germany.
Nat Commun. 2025 Aug 22;16(1):7850. doi: 10.1038/s41467-025-63225-4.
Application of photoactive transition metal complexes in lighting, imaging, sensing, and photocatalysis is usually based on the triplet metal-to-ligand charge transfer (MLCT) excited state of precious metal complexes with 4/5d valence electron configurations. These photocatalysts exhibit excited state lifetimes exceeding hundreds of nanoseconds. Simple 3d transition metal complexes containing abundant metals exhibit lifetimes below 1-2 nanoseconds, and they require multistep ligand syntheses mitigating large-scale implementation. We report that a commercially available bis(imidazolium) pyridine pro-ligand [Hpbmi] and a manganese(II) salt yield the tetracarbene manganese(I) complex [Mn(pbmi)]. This complex phosphoresces at room temperature in fluid solution from a MLCT state with a lifetime of 190 ns. In combination with the reversible [Mn(pbmi)] process, this translates to an excited state capable of reducing benzophenone. Combination of manganese(I) with rigid carbene/pyridine ligands expands key strategies for photoactive 3d metal complexes of earth-abundant metals with MLCT lifetimes rivalling those of precious metals and providing a conceptual starting point for a sustainable photochemistry.
光活性过渡金属配合物在照明、成像、传感和光催化中的应用通常基于具有4/5d价电子构型的贵金属配合物的三重态金属到配体电荷转移（MLCT）激发态。这些光催化剂的激发态寿命超过数百纳秒。含有丰富金属的简单3d过渡金属配合物的寿命低于1-2纳秒，并且它们需要多步配体合成，这不利于大规模应用。我们报道，一种市售的双（咪唑鎓）吡啶前体配体[Hpbmi]和一种锰（II）盐生成了四卡宾锰（I）配合物[Mn（pbmi）]。该配合物在室温下于流体溶液中从MLCT态发出磷光，寿命为190 ns。与可逆的[Mn（pbmi）]过程相结合，这转化为一种能够还原二苯甲酮的激发态。锰（I）与刚性卡宾/吡啶配体的结合扩展了用于地球丰富金属的光活性3d金属配合物的关键策略，其MLCT寿命可与贵金属相媲美，并为可持续光化学提供了一个概念起点。
