Blancafort Lluís
Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona (Spain).
Chemphyschem. 2014 Oct 20;15(15):3166-81. doi: 10.1002/cphc.201402359. Epub 2014 Aug 26.
The role of extended seams of conical intersection in excited-state mechanisms is reviewed. Seams are crossings of the potential energy surface in many dimensions where the decay from the excited to the ground state can occur, and the extended seam is composed of different segments lying along a reaction coordinate. Every segment is associated with a different primary photoproduct, which gives rise to competing pathways. This idea is first illustrated for fulvene and ethylene, and then it is used to explain more complex cases such as the dependence of the isomerisation of retinal chromophore isomers on the protein environment, the dependence of the efficiency of the azobenzene photochemical switch on the wavelength of irradiation and the direction of the isomerisation, and the coexistence of different mechanisms in the photo-induced Wolff rearrangement of diazonaphthoquinone. The role of extended seams in the photophysics of the DNA nucleobases and the relationship between two-state seams and three-state crossings is also discussed. As an outlook, the design of optical control strategies based on the passage of the excited molecule through the seam is considered, and it is shown how the excited-state lifetime of fulvene can be modulated by shaping the energy of the seam.
本文综述了锥形交叉的扩展接缝在激发态机制中的作用。接缝是多维势能面的交叉点，激发态到基态的衰变可能在此发生，扩展接缝由沿反应坐标排列的不同片段组成。每个片段都与一种不同的初级光产物相关联，这导致了竞争途径。这个概念首先以富烯和乙烯为例进行说明，然后用于解释更复杂的情况，如视黄醛发色团异构体的异构化对蛋白质环境的依赖性、偶氮苯光化学开关的效率对照射波长和异构化方向的依赖性，以及重氮萘醌光诱导沃尔夫重排中不同机制的共存。还讨论了扩展接缝在DNA核碱基光物理中的作用以及双态接缝与三态交叉之间的关系。展望未来，考虑了基于激发分子通过接缝的光学控制策略的设计，并展示了如何通过调整接缝能量来调节富烯的激发态寿命。
