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Vibrational coherence and quantum yield of retinal-chromophore-inspired molecular switches.
Faraday Discussions ( IF 3.3 ) Pub Date : 2019-12-16 , DOI: 10.1039/c9fd00062c Moussa Gueye 1 , Marco Paolino , Etienne Gindensperger , Stefan Haacke , Massimo Olivucci , Jérémie Léonard
Faraday Discussions ( IF 3.3 ) Pub Date : 2019-12-16 , DOI: 10.1039/c9fd00062c Moussa Gueye 1 , Marco Paolino , Etienne Gindensperger , Stefan Haacke , Massimo Olivucci , Jérémie Léonard
Affiliation
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UV-Vis transient absorption (TA) spectroscopy is used to carry out a systematic investigation of the ultrafast C[double bond, length as m-dash]C double photoisomerization dynamics and quantum yield of each isomer of a set of six chromophores based on the same retinal-inspired, indanylidene pyrrolinium (IP) molecular framework. All compounds undergo a sub-picosecond photoisomerization, and can be categorized within two photoisomerization scenarios. Scenario I corresponds to compounds which display the signatures of a vibrationally coherent reactive motion through the conical intersection, with different degrees of vibrational coherence. Qualitatively distinct TA signatures are observed for other compounds which are therefore proposed to obey scenario II, referring to an intermediate regime between scenario I and a thermally-equilibrated, fully stochastic photoreaction. Remarkably, the photoisomerization scenario is observed to correlate with the computed distortion from planarity of the ground state equilibrium geometry, reflecting the torsional strain that would be released after photoexcitation. The most planar compounds - i.e. those having a C[double bond, length as m-dash]C double bond pre-twist of less than 10° - obey scenario II, while compounds obeying scenario I have larger pre-twists. The most pre-twisted compounds (>15°) show pronounced oscillatory signatures of a reaction-induced, low-frequency vibrational wavepacket observed in the S0 photoproduct and assigned to the torsion mode of the reaction coordinate, thus mimicking the vibrationally coherent photoisomerization dynamics of the rhodopsin protein. Importantly, the systematic comparison of all photoisomerization quantum yields does however not reveal any correlation with observables such as excited state life time, vibrational coherence, absorption wavelengths or degree of pre-twisting.
中文翻译：
视网膜发色团激发的分子开关的振动相干性和量子产率。
使用UV-Vis瞬态吸收（TA）光谱对基于六种发色团的每一个异构体的超快C [双键]，[m-dash] C双光异构化长度和每个异构体的量子产率进行了系统研究。相同的视网膜激发茚满亚吡咯烷鎓（IP）分子框架。所有化合物都会经历亚皮秒级的光异构化，可以归类为两种光异构化方案。方案I对应于通过圆锥形相交显示振动相干反应运动特征的化合物，具有不同程度的振动相干性。在其他化合物中观察到质的截然不同的TA标记，因此建议遵守方案II，是指方案I与热平衡的中间状态，完全随机的光反应。值得注意的是，观察到光异构化情况与根据基态平衡几何学的平面度计算出的畸变相关，反映了在光激发后将释放的扭转应变。最平坦的化合物（即，那些具有C 10双键，长度为m-C双键的预扭转小于10°的化合物）遵循方案II，而服从方案I的化合物具有较大的预扭转。最扭曲的化合物（> 15°）在S0光产物中观察到了由反应引起的低频振动波包的明显振荡特征，并赋予了反应坐标的扭转模式，从而模仿了D2的振动相干光异构化动力学。视紫红质蛋白。重要的，
更新日期：2019-12-17
中文翻译：
视网膜发色团激发的分子开关的振动相干性和量子产率。
使用UV-Vis瞬态吸收（TA）光谱对基于六种发色团的每一个异构体的超快C [双键]，[m-dash] C双光异构化长度和每个异构体的量子产率进行了系统研究。相同的视网膜激发茚满亚吡咯烷鎓（IP）分子框架。所有化合物都会经历亚皮秒级的光异构化，可以归类为两种光异构化方案。方案I对应于通过圆锥形相交显示振动相干反应运动特征的化合物，具有不同程度的振动相干性。在其他化合物中观察到质的截然不同的TA标记，因此建议遵守方案II，是指方案I与热平衡的中间状态，完全随机的光反应。值得注意的是，观察到光异构化情况与根据基态平衡几何学的平面度计算出的畸变相关，反映了在光激发后将释放的扭转应变。最平坦的化合物（即，那些具有C 10双键，长度为m-C双键的预扭转小于10°的化合物）遵循方案II，而服从方案I的化合物具有较大的预扭转。最扭曲的化合物（> 15°）在S0光产物中观察到了由反应引起的低频振动波包的明显振荡特征，并赋予了反应坐标的扭转模式，从而模仿了D2的振动相干光异构化动力学。视紫红质蛋白。重要的，
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