Influence of 4 and 4′ Substituents on Ru III/II Bipyridyl Self-Exchange Electron Transfer Across Nanocrystalline TiO 2 Surfaces
Influence of 4 and 4′ Substituents on Ru III/II Bipyridyl Self-Exchange Electron Transfer Across Nanocrystalline TiO 2 Surfaces
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4 和 4-取代基对纳米晶 TiO 2 表面 Ru III/II 联吡啶自交换电子转移的影响
DOI：
10.1021/acs.jpcc.8b05281
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Meyer, Gerald J.
中科院分区：
文献类型：
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作者：
Motley, Tyler C.;Brady, Matthew D.;Meyer, Gerald J.
氧化物表面的横向自交换电子转移对于许多太阳能捕获和转换方案是重要的。用一系列[Ru（R2 bpy）2（P）]2+型Ru Ⅱ多吡啶化合物研究了取代基对侧向Ru Ⅲ/II自交换电子转移的影响，其中P为2，2 ′-联吡啶-4，4 ′-二膦酸，R2 bpy为4，4 ′-取代的2，2 ′-联吡啶，具有6个不同的R基团：− OCH 3、−C（CH 3）3、− CH 3、−H、−Br和− CF 3。选择这些官能团主要是因为它们的吸电子或供电子能力。用计时光散射法测定了表观扩散系数DCA，其值在2.8 × 10 ~（-11）~ 7.9 × 10 ~（-9）cm ~ 2/s之间。的measuredDCA值没有表现出相关性的吸电子或供电子能力的官能团，而是与取代基的空间尺寸，也影响了饱和表面覆盖度，从而分子间的距离。在假定分子间距离的情况下，发现自交换速率与距离呈指数关系，β = 1.2 ± 0.2 π-1。通过改变表面覆盖度，得到β = 1.18 ± 0.09 Ω-1，表明取代基的空间尺寸是控制界面上侧向RuIII/II自交换电子转移速率的主要因素.
Lateral self-exchange electron transfer across oxide surfaces is important to many solar energy capture and conversion schemes. Substituent effects on lateral RuIII/IIself-exchange electron transfer were studied using a series of RuIIpolypyridyl compounds of the type [Ru(R2bpy)2(P)]2+, where P is 2,2′-bipyridyl-4,4′-diphosphonic acid and R2bpy was a 4,4′-substituted-2,2′-bipyridine with six different R groups: −OCH3, −C(CH3)3, −CH3, −H, −Br, and −CF3. These functional groups were chosen mainly for their electron-withdrawing or -donating ability. Chronoabsorptometry was used to probe the apparent diffusion coefficient,DCA, that was proportional to the self-exchange rate constants, and these values were found to be between 2.8 × 10–11and 7.9 × 10–9cm2/s. The measuredDCAvalues showed no correlation with the electron-withdrawing or -donating ability of the functional groups, but were instead correlated with the steric size of the substituents that also influenced the saturation surface coverage and thus the intermolecular distance. With some assumptions to estimate the intermolecular distance, the self-exchange rates were found to possess an exponential dependence with the distance, β = 1.2 ± 0.2 Å–1. Independent tests of the were carried out by varying the surface coverages from which β = 1.18 ± 0.09 Å–1was found. The results indicate that the substituent’s steric size is the dominant factor that controls lateral RuIII/IIself-exchange electron-transfer rates at these interfaces.