Baldwin Matthew T, Zosel Nicholas A, Shoemaker Aaron H, Mara Michael W, Haddock Tyler N, Chen Lin X, Hunter Bryan M
Northwestern University, Department of Chemistry, Evanston, Illinois 60208, United States.
Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.
Inorg Chem. 2025 Jul 14;64(27):13765-13774. doi: 10.1021/acs.inorgchem.5c01300. Epub 2025 Jul 1.
Replacing precious metals with abundant metals is an important research focus in photochemical energy conversion and storage to meet global energy demands. However, transition metal complexes (TMCs) based on abundant 3 metals typically possess photochemical disadvantages─such as short charge-transfer excited-state lifetimes─and molecular modifications have focused on optimizing the interplay of structure, dynamics, and energetics to overcome their limitations. One strategy to do so is the use of bespoke ligands that can extend the lifetimes of chemically useful excited states. Here, we report the synthesis and characterization of novel Fe(II) complexes featuring lengthy polypyridyl ligands that can be readily synthesized. Steady-state and transient absorption spectroscopies indicate that these complexes have desirable properties and their excited metal-to-ligand charge-transfer states live an order of magnitude longer than in the benchmark [Fe(bpy)]. This lifetime is largely preserved in the heteroleptic complexes, thereby enabling the preparation of asymmetric complexes. Additionally, we apply nonradiative transition theory to explain the long-time decay kinetics. In light of their ease of preparation and reasonable excited-state lifetimes, we suggest the use of these complexes in Fe(II) dye-sensitized solar cells, where the rate of charge injection would be competitive with increased lifetime.
用储量丰富的金属取代贵金属是光化学能量转换和存储领域的一个重要研究重点，以满足全球能源需求。然而，基于储量丰富的金属的过渡金属配合物（TMCs）通常具有光化学缺点，比如电荷转移激发态寿命短，并且分子修饰一直专注于优化结构、动力学和能量学之间的相互作用以克服其局限性。这样做的一种策略是使用定制配体，其可以延长化学上有用的激发态的寿命。在此，我们报道了具有易于合成的长聚吡啶配体的新型Fe(II)配合物的合成与表征。稳态和瞬态吸收光谱表明这些配合物具有理想的性质，并且它们的激发态金属到配体电荷转移态的寿命比基准配合物[Fe(bpy)]长一个数量级。这种寿命在杂配配合物中基本得以保留，从而能够制备不对称配合物。此外，我们应用非辐射跃迁理论来解释长时间的衰减动力学。鉴于它们易于制备且激发态寿命合理，我们建议在Fe(II)染料敏化太阳能电池中使用这些配合物，其中电荷注入速率将与延长的寿命具有竞争力。
