Ahmed Ejaz, Chizhik Stanislav, Sidelnikov Anatoly, Boldyreva Elena, Naumov Panče
Smart Materials Lab, New York University, Abu Dhabi, POB 129188, Abu Dhabi 00000, U.A.E.
Institute of Solid State Chemistry and Mechanochemistry SB RAS, ul. Kutateladze, 18, Novosibirsk 630128, Russian Federation.
Inorg Chem. 2022 Feb 28;61(8):3573-3585. doi: 10.1021/acs.inorgchem.1c03607. Epub 2022 Feb 16.
Exposure of a photoreactive single crystal to light with a wavelength offset from its absorption maximum can have two distinct effects. The first is the "direct" effect, wherein the excited state generated in individual chemical species is influenced. The second is the "indirect" effect, which describes the penetration of light into the crystal and hence the spatial propagation and completeness of transformation. We illustrate using the nitro-nitrito isomerization of [Co(NH)NO]Cl(NO) as an example that the direct and indirect effects can be independently determined. This is achieved by comparing the dynamics of macroscopic crystal deformation (bending curvature and crystal elongation) induced by the photochemical reaction when irradiating a crystal at the absorption maximum and at different band edges (above or below the maximum) of the same band. Quantitative description of the macroscopic strain dynamics in comparison with experiments allowed us to suggest that irradiation at different tails of the same absorption band causes isomerization to proceed via different excited states and an additional photochemical reaction (presumably, reverse nitrito-nitro isomerization) can occur on irradiation at the ligand-field band edges.
将光反应性单晶暴露于波长偏离其吸收最大值的光下会产生两种不同的效应。第一种是“直接”效应，其中单个化学物种中产生的激发态会受到影响。第二种是“间接”效应，它描述了光进入晶体的情况，以及转化的空间传播和完整性。我们以[Co(NH)NO]Cl(NO)的硝基-亚硝酸根异构化为例进行说明，直接效应和间接效应可以独立确定。这是通过比较在吸收最大值以及同一能带的不同带边（高于或低于最大值）照射晶体时，光化学反应引起的宏观晶体变形（弯曲曲率和晶体伸长）的动力学来实现的。与实验相比，对宏观应变动力学的定量描述使我们能够提出，在同一吸收带的不同尾部进行照射会导致异构化通过不同的激发态进行，并且在配体场带边照射时可能会发生额外的光化学反应（大概是亚硝酸根-硝基的反向异构化）。
