Photoinduced electron transfer systems can mimic certain features of natural photosynthetic reaction centers, which are crucial for solar energy production. Among other tetra-pyrroles, the versatile chemical and photophysical properties of corroles make them very promising donors applicable in donor–acceptor complexes. Here, we present a first comprehensive study of ultrafast photoinduced electron transfer in a self-assembling sulfonated aluminum corrole–methylviologen complex combining visible and mid-IR transient absorption spectroscopy. The noncovalent D–A association of the corrole–methylviologen complex has the great advantage that photoinduced charge separation becomes possible even though the back electron transfer (BET) rate is large. Initial forward electron transfer from corrole to methylviologen is observed on an ∼130 fs time scale. Subsequent back electron transfer takes place with τ_BET = (1.8 ± 0.5) ps, revealing very complex relaxation dynamics. Direct probing in the mid-IR allows us to unravel the back electron transfer and cooling dynamics/electronic reorganization. Upon tracing the dynamics of the methylviologen-radical marker band at 1640 cm^–1 and the C═C stretching of corrole at around 1500 cm^–1, we observe that large amounts of excess energy survive the back transfer, leading to the formation of hot ground state absorption. A closer examination of the signal after 300 ps, surviving the back transfer, exhibits a charge-separation yield of 10–15%.

中文翻译：

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自组装磺化铝Corrole-甲基紫精复合物中的超快电子转移

光致电子转移系统可以模仿自然光合反应中心的某些特征，这对太阳能生产至关重要。在其他四吡咯中，corroles 的多功能化学和光物理特性使其成为非常有前途的供体，适用于供体 - 受体复合物。在这里，我们首次综合研究了结合可见光和中红外瞬态吸收光谱的自组装磺化铝-甲基紫精复合物中的超快光致电子转移。非共价 D - corrole - 甲基紫精复合物的组合具有很大的优势，即使背电子转移 (BET) 速率很大，光诱导电荷分离也成为可能。在~130 fs 时间尺度上观察到从corrole 到甲基紫精的初始正向电子转移。_BET = (1.8 ± 0.5) ps，揭示了非常复杂的松弛动力学。中红外直接探测使我们能够解开背电子转移和冷却动力学/电子重组。通过追踪 1640 cm ^–1处的甲基紫精-自由基标记带的动力学和大约 1500 cm ^–1处 corrole 的 C=C 拉伸，我们观察到大量多余的能量在反向转移中幸存下来，导致形成热基态吸收。在 300 ps 后仔细检查信号，在反向转移中幸存下来，显示出 10-15% 的电荷分离率。