Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors.
Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors.
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球形 2D 和 3D 微反应器中扩散的自由基对的自旋选择性反应的理论描述。
DOI：
10.1063/1.4928648
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
N. Lukzen
中科院分区：
文献类型：
--
作者：
K. Ivanov;V. Sadovsky;N. Lukzen
在这项工作中，我们在球形“微反应器”中处理一对自由基对（RP）的自旋选择性重组，即限制在胶束、囊泡或脂质体中的 RP。我们考虑之前提出的微反应器模型，其中一个自由基位于胶束的中心，另一个自由基在胶束内进行三维扩散。此外，我们提出了一种二维模型，其中一个自由基位于球体的“极点”，而另一个自由基在球面上扩散。对于该模型，我们根据二维扩散运动的自由格林函数获得了 RP 复合产率的通用解析表达式。反过来，该格林函数通过勒让德函数表示，因此考虑了受限球面及其曲率上的扩散。所获得的表达式允许计算任意磁场强度下的RP复合效率。我们采用相同的几何参数（即微反应器半径和自由基的最近接近距离）、化学反应性、RP 中的磁相互作用和扩散系数对两个模型进行了比较。发现两个模型的预测之间存在显着差异，这完全源于维度效应：对于不同的空间维度，自由基扩散接触的统计数据变得不同，从而改变了反应产率。我们计算了不同尺寸微反应器下反应产物的化学诱导动态核极化、交换相互作用和自旋弛豫率对 RP 反应产率和化学诱导动态核极化的磁场依赖性。有趣的是，由于反应物的扩散接触和自旋动力学之间错综复杂的相互作用，反应产率对微反应器半径的依赖性是非单调的。我们的结果对于（i）解释有限空间中磁场对 RP 重组影响的实验数据和（ii）描述主要发生在生物膜表面的化学反应（即脂质过氧化反应）的动力学具有重要意义。
In this work, we treat spin-selective recombination of a geminate radical pair (RP) in a spherical "microreactor," i.e., of a RP confined in a micelle, vesicle, or liposome. We consider the microreactor model proposed earlier, in which one of the radicals is located at the center of the micelle and the other one undergoes three-dimensional diffusion inside the micelle. In addition, we suggest a two-dimensional model, in which one of the radicals is located at the "pole" of the sphere, while the other one diffuses on the spherical surface. For this model, we have obtained a general analytical expression for the RP recombination yield in terms of the free Green function of two-dimensional diffusion motion. In turn, this Green function is expressed via the Legendre functions and thus takes account of diffusion over a restricted spherical surface and its curvature. The obtained expression allows one to calculate the RP recombination efficiency at an arbitrary magnetic field strength. We performed a comparison of the two models taking the same geometric parameters (i.e., the microreactor radius and the closest approach distance of the radicals), chemical reactivity, magnetic interactions in the RP and diffusion coefficient. Significant difference between the predictions of the two models is found, which is thus originating solely from the dimensionality effect: for different dimensionality of space, the statistics of diffusional contacts of radicals becomes different altering the reaction yield. We have calculated the magnetic field dependence of the RP reaction yield and chemically induced dynamic nuclear polarization of the reaction products at different sizes of the microreactor, exchange interaction, and spin relaxation rates. Interestingly, due to the intricate interplay of diffusional contacts of reactants and spin dynamics, the dependence of the reaction yield on the microreactor radius is non-monotonous. Our results are of importance for (i) interpreting experimental data for magnetic field effects on RP recombination in confined space and (ii) for describing kinetics of chemical reactions, which occur predominantly on the surfaces of biomembranes, i.e., lipid peroxidation reactions.
隐色体的磁敏感光诱导反应与其作为磁感受器的作用相符
DOI：
10.1073/pnas.1118959109
发表时间：
2012-03-27
影响因子：
11.1
作者：
Maeda, Kiminori;Robinson, Alexander J.;Hore, P. J.
通讯作者：
Hore, P. J.