Bennett Doran I G, Malý Pavel, Kreisbeck Christoph, van Grondelle Rienk, Aspuru-Guzik Alán
Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States.
Bio-Inspired Solar Energy Program , Canadian Institute for Advanced Research , Toronto , Ontario M5G 1Z8 , Canada.
J Phys Chem Lett. 2018 May 17;9(10):2665-2670. doi: 10.1021/acs.jpclett.8b00844. Epub 2018 May 7.
Following the observation of coherent oscillations in nonlinear spectra of photosynthetic pigment protein complexes, in particular, phycobilliproteins such as PC645, coherent vibronic transport has been suggested as a design principle for novel light-harvesting materials. Vibronic transport between energetically remote pigments is coherent when the presence of a vibration resonant with the electronic energy gap supports transient delocalization between the electronic excited states. We establish the mechanism of vibronic transport for a model heterodimer across a wide range of molecular parameter values. The resulting mechanistic map demonstrates that the molecular parameters of phycobiliproteins in fact support incoherent vibronic transport. This result points to an important design principle: Incoherent vibronic transport is more efficient than a coherent mechanism when energetic disorder exceeds the coupling between the donor and vibrationally excited acceptor states. Finally, our results suggest that the role of coherent vibronic transport in pigment protein complexes should be reevaluated.
在观察到光合色素蛋白复合物的非线性光谱中的相干振荡后，特别是诸如PC645之类的藻胆蛋白，相干振动子传输已被认为是新型光捕获材料的一种设计原则。当存在与电子能隙共振的振动时，能量上相距较远的色素之间的振动子传输是相干的，这支持了电子激发态之间的瞬态离域。我们建立了一个模型异二聚体在广泛的分子参数值范围内的振动子传输机制。由此产生的机制图表明，藻胆蛋白的分子参数实际上支持非相干振动子传输。这一结果指出了一个重要的设计原则：当能量无序超过供体与振动激发受体态之间的耦合时，非相干振动子传输比相干机制更有效。最后，我们的结果表明，应重新评估相干振动子传输在色素蛋白复合物中的作用。
