Zarrabi Niloofar, Bayard Brandon J, Seetharaman Sairaman, Holzer Noah, Karr Paul, Ciuti Susanna, Barbon Antonio, Di Valentin Marilena, van der Est Art, D'Souza Francis, Poddutoori Prashanth K
Department of Chemistry & Biochemistry, University of Minnesota Duluth, 1039 University Drive, Duluth, Minnesota 55812, USA.
Department of Chemistry, University of North Texas, 1155 Union Circle, # 305070, Denton, Texas 76203-5017, USA.
Phys Chem Chem Phys. 2021 Jan 21;23(2):960-970. doi: 10.1039/d0cp05783e.
Photosensitizers with high energy, long lasting charge-transfer states are important components in systems designed for solar energy conversion by multistep electron transfer. Here, we show that in a push-pull type, μ-oxo-bridged porphyrin heterodimer composed of octaethylporphyrinatoaluminum(iii) and octaethylporphyrinatophosphorus(v), the strong excitonic coupling between the porphyrins and the different electron withdrawing abilities of Al(iii) and P(v) promote the formation of a high energy CT state. Using, an array of optical and magnetic resonance spectroscopic methods along with theoretical calculations, we demonstrate photodynamics of the heterodimer that involves the initial formation of a singlet CT which relaxes to a triplet CT state with a lifetime of ∼130 ps. The high-energy triplet CT state (3CT = 1.68 eV) lasts for nearly 105 μs prior to relaxing to the ground state.
具有高能量、长寿命电荷转移态的光敏剂是通过多步电子转移进行太阳能转换的系统中的重要组成部分。在此，我们表明，在由八乙基卟啉铝(iii)和八乙基卟啉磷(v)组成的推挽型μ-氧桥联卟啉异二聚体中，卟啉之间的强激子耦合以及Al(iii)和P(v)不同的吸电子能力促进了高能量电荷转移（CT）态的形成。使用一系列光学和磁共振光谱方法以及理论计算，我们证明了异二聚体的光动力学，其中涉及单重态CT的初始形成，其弛豫到三重态CT态，寿命约为130皮秒。高能三重态CT态（3CT = 1.68电子伏特）在弛豫到基态之前持续近105微秒。
