Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA.
J Am Chem Soc. 2013 Jun 12;135(23):8492-5. doi: 10.1021/ja4035945. Epub 2013 May 29.
Electron transfer (ET) reactions of colloidal 3-5 nm diameter ZnO nanocrystals (NCs) with molecular reagents are explored in aprotic solvents. Addition of an excess of the one-electron reductant Cp2Co (Cp = pentamethylcyclopentadienyl) gives NCs that are reduced by up to 1-3 electrons per NC. Protons can be added stoichiometrically to the NCs by either a photoreduction/oxidation sequence or by addition of acid. The added protons facilitate the reduction of the ZnO NCs. In the presence of acid, NC reduction by Cp2Co can be increased to over 15 electrons per NC. The weaker reductant Cp2Cr transfers electrons only to ZnO NCs in the presence of protons. Cp2M(+) counterions are much less effective than protons at stabilizing reduced NCs. With excess Cp2Co or Cp*2Cr, the extent of reduction increases roughly linearly with the number of protons added. Some of the challenges in understanding these results are discussed.
在非质子溶剂中研究了胶体 3-5nm 直径 ZnO 纳米晶体（NCs）与分子试剂的电子转移（ET）反应。加入过量的单电子还原剂 Cp2Co（Cp=五甲基环戊二烯基），可使 NC 还原 1-3 个电子。通过光还原/氧化序列或添加酸，可以将质子以化学计量比添加到 NC 中。加入的质子有利于 ZnO NC 的还原。在酸存在下，Cp2Co 还原 NC 的反应可增加到每个 NC 超过 15 个电子。较弱的还原剂 Cp2Cr 只有在存在质子的情况下才能将电子转移到 ZnO NCs 上。Cp2M(+) 抗衡离子在稳定还原 NC 方面的效果远不如质子。在过量的 Cp2Co 或 Cp*2Cr 存在下，还原程度大致随加入的质子数量呈线性增加。讨论了理解这些结果所面临的一些挑战。
