Loague Quentin R, Heidari Marzieh, Mann Hayden J, Danilov Evgeny O, Castellano Felix N, Galoppini Elena, Meyer Gerald J
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Department of Chemistry, Rutgers University, 73 Warren Street, Newark, New Jersey 07102, United States.
ACS Cent Sci. 2024 Nov 11;10(11):2132-2144. doi: 10.1021/acscentsci.4c01106. eCollection 2024 Nov 27.
Structural gating provides a molecular means to transfer electrons preferentially in one desired vectorial direction, a behavior needed for applications in artificial photosynthesis. At the interfaces utilized herein, visible-light absorption by a transition metal complex a "structural gate" by planarization of otherwise rotating phenyl rings in phenylene ethynylene (PE) bridge units. Planarization provides a conjugated pathway for electron flow toward a conductive oxide surface. Interfacial electron transfer to the oxide restores rotation and the gate to the unwanted recombination reaction. This structural gating results in nearly quantitative long-distance (>20 Å) interfacial electron transfer that occurs ∼1000 times faster than transfer in the opposite direction. A comparative kinetic study of these complexes with those that contain ionic bridge units, without gating function, as a function of the applied potential and hence -Δ° provided a physical basis for the structural gating. A small distance-dependent reorganization energy with weak electronic coupling underlies the success of this gate that enables efficient long-distance electron transfer and slow recombination.
结构门控提供了一种分子手段，可优先沿一个所需的矢量方向转移电子，这是人工光合作用应用所需的一种行为。在本文所使用的界面处，过渡金属配合物吸收可见光——通过亚苯基乙炔（PE）桥单元中原本旋转的苯环平面化形成一个“结构门”。平面化为电子流向导电氧化物表面提供了一条共轭途径。向氧化物的界面电子转移恢复了旋转，并使门控避免了不必要的复合反应。这种结构门控导致了近乎定量的长距离（>20 Å）界面电子转移，其发生速度比相反方向的转移快约1000倍。对这些配合物与那些不含门控功能的离子桥单元的配合物进行比较动力学研究，作为外加电势以及因此的-Δ°的函数，为结构门控提供了物理基础。这种门控成功的基础是具有弱电子耦合的小距离依赖重组能，它能够实现高效的长距离电子转移和缓慢的复合。
