Haimerl Josef, Ghosh Indrajit, König Burkhard, Vogelsang Jan, Lupton John M
Institut für Experimentelle und Angewandte Physik , Universität Regensburg , 93040 Regensburg , Germany . Email:
Institut für Organische Chemie , Universität Regensburg , 93040 Regensburg , Germany.
Chem Sci. 2018 Oct 22;10(3):681-687. doi: 10.1039/c8sc03860k. eCollection 2019 Jan 21.
The chemistry of life is founded on light, so is it appropriate to think of light as a chemical substance? Planck's quantization offers a metric analogous to Avogadro's number to relate the number of particles to an effective reaction of single molecules and photons to form a new compound. A rhodamine dye molecule serves as a dehalogenating photocatalyst in a consecutive photoelectron transfer (conPET) process which adds the energy of two photons, with the first photon inducing radical formation and the second photon triggering PET to the substrate molecule. Rather than probing catalytic heterogeneity and dynamics on the single-molecule level, single-photon synthesis is demonstrated: the light quantum constitutes a reactant for the single substrate molecule in a dye-driven reaction. The approach illustrates that molecular diffusion and excited-state internal conversion are not limiting factors in conPET reaction kinetics because of catalyst-substrate preassociation. The effect could be common to photoredox catalysis, removing the conventional requirement of long excited-state lifetimes.
生命的化学建立在光的基础之上，那么将光视为一种化学物质是否合适呢？普朗克量子化提供了一种类似于阿伏伽德罗常数的度量，用于将粒子数量与单分子和光子形成新化合物的有效反应联系起来。一种罗丹明染料分子在连续光电子转移（conPET）过程中作为脱卤光催化剂，该过程会添加两个光子的能量，第一个光子诱导自由基形成，第二个光子触发向底物分子的光电子转移。这里展示的不是在单分子水平上探测催化的非均一性和动力学，而是单光子合成：在染料驱动的反应中，光量子构成单个底物分子的反应物。该方法表明，由于催化剂 - 底物预缔合，分子扩散和激发态内部转换不是conPET反应动力学的限制因素。这种效应可能在光氧化还原催化中很常见，消除了对长激发态寿命的传统要求。
