Design-specific control over excited-state dynamics is necessary for any application seeking to convert light into chemical potential. Such control is especially desirable in iron( ii )-based chromophores, which are an Earth-abundant option for a wide range of photo-induced electron-transfer applications including solar energy conversion 1 and catalysis 2 . However, the sub-200-femtosecond lifetimes of the redox-active metal-to-ligand charge transfer (MLCT) excited states typically encountered in these compounds have largely precluded their widespread use 3 . Here we show that the MLCT lifetime of an iron( ii ) complex can be manipulated using information from excited-state quantum coherences as a guide to implementing synthetic modifications that can disrupt the reaction coordinate associated with MLCT decay. We developed a structurally tunable molecular platform in which vibronic coherences—that is, coherences reflecting a coupling of vibrational and electronic degrees of freedom—were observed in ultrafast time-resolved absorption measurements after MLCT excitation of the molecule. Following visualization of the vibrational modes associated with these coherences, we synthetically modified an iron( ii ) chromophore to interfere with these specific atomic motions. The redesigned compound exhibits a MLCT lifetime that is more than a factor of 20 longer than that of the parent compound, indicating that the structural modification at least partially decoupled these degrees of freedom from the population dynamics associated with the electronic-state evolution of the system. These results demonstrate that using excited-state coherence data may be used to tailor ultrafast excited-state dynamics through targeted synthetic design. Information from quantum coherence observations guides synthetic modifications of an iron-based chromophore, increasing the excited-state dynamics lifetime by a factor of 20, with implications for photo-induced electron-transfer applications.

中文翻译：

---

利用激发态相干性对超快动力学进行综合控制

对于任何寻求将光转化为化学势的应用，对激发态动力学的特定设计控制是必要的。这种控制在基于铁 (ii) 的发色团中尤其理想，它是地球上丰富的选择，适用于广泛的光诱导电子转移应用，包括太阳能转换 1 和催化 2 。然而，这些化合物中通常遇到的氧化还原活性金属到配体电荷转移 (MLCT) 激发态的亚 200 飞秒寿命在很大程度上阻碍了它们的广泛使用 3。在这里，我们表明可以使用来自激发态量子相干的信息作为实施合成修饰的指南来操纵铁（ii）配合物的 MLCT 寿命，这些修饰可以破坏与 MLCT 衰变相关的反应坐标。我们开发了一个结构可调的分子平台，在分子的 MLCT 激发后，在超快时间分辨吸收测量中观察到振动相干性 - 即反映振动和电子自由度耦合的相干性。在对与这些相干性相关的振动模式进行可视化之后，我们综合修改了铁（ii）发色团以干扰这些特定的原子运动。重新设计的化合物的 MLCT 寿命比母体化合物长 20 倍以上，这表明结构修改至少部分地将这些自由度与与系统电子态演化相关的种群动态分离. 这些结果表明，使用激发态相干数据可用于通过有针对性的合成设计来定制超快激发态动力学。来自量子相干观测的信息指导铁基发色团的合成修饰，将激发态动力学寿命增加 20 倍，对光致电子转移应用产生影响。