Directly Attached Bisdonor-BF2 Chelated Azadipyrromethene-Fullerene Tetrads for Promoting Ground and Excited State Charge Transfer
Directly Attached Bisdonor-BF2 Chelated Azadipyrromethene-Fullerene Tetrads for Promoting Ground and Excited State Charge Transfer
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DOI：
10.1002/chem.201700200
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发表时间：
2017-03-28
影响因子：
4.3
通讯作者：
D'Souza, Francis
中科院分区：
文献类型：
--
作者：
Collini, Melissa A.;Thomas, Michael B.;D'Souza, Francis
在天然和合成的供体-受体系统中发生的电子和能量转移事件的效率和机制取决于它们的距离、相对取向和周围介质的性质。从模型研究中获得的基础知识是构建高效能量收集和光电设备的关键。在供体-受体系统中，经常寻求更快的电荷分离和更慢的电荷复合。在我们继续努力建立供体受体系统使用近红外敏化剂，在本研究中，我们报告地面和激发态电荷转移在新合成的，直接连接的四元特征bisdonor（供体=吩噻嗪和二茂铁），BF 2-螯合氮杂二吡咯甲烷（azaBODIPY）和C-60实体。使用多步合成程序合成的四联体揭示了涉及供体和azaBODIPY实体的基态中的强电荷转移相互作用。近红外发射azaBODIPY充当光敏电子受体沿着富勒烯，而吩噻嗪和二茂铁实体充当电子供体。在极性和非极性溶剂介质中，通过飞秒瞬态吸收光谱研究，三联体（双给体-azaBODIPY）和四联体揭示了超快光致电荷分离，导致D中心点+-azaBODIPY（中心点-）-C-60和D中心点+-azaBODIPY-C-60（中心点-）（D =吩噻嗪或二茂铁）电荷分离态。电荷分离态填充azaBODIPY的三重激发态，然后返回到基态。
The efficiency and mechanism of electron-and energy-transfer events occurring in both natural and synthetic donor-acceptor systems depend on their distance, relative orientation, and the nature of the surrounding media. Fundamental knowledge gained from model studies is key to building efficient energy harvesting and optoelectronic devices. Faster charge separation and slower charge recombination in donor-acceptor systems is often sought out. In our continued effort to build donor-acceptor systems using near-IR sensitizers, in the present study, we report ground and excited-state charge transfer in newly synthesized, directly linked tetrads featuring bisdonor (donor = phenothiazine and ferrocene), BF2-chelated azadipyrromethane (azaBODIPY) and C-60 entities. The tetrads synthesized using multi-step synthetic procedure revealed strong charge-transfer interactions in the ground state involving the donor and azaBODIPY entities. The near-IR emitting azaBODIPY acted as a photosensitizing electron acceptor along with fullerene whereas the phenothiazine and ferrocene entities acted as electron donors. The triads (bisdonor-azaBODIPY) and tetrads revealed ultrafast photoinduced charge separation leading to D center dot+-azaBODIPY(center dot-)-C-60 and D center dot+-azaBODIPY-C-60(center dot-) (D = phenothiazine or ferrocene) charge separated states from the femtosecond transient absorption spectral studies in both polar and nonpolar solvent media. The charge-separated states populated the triplet excited state of azaBODIPY prior returning to the ground state.