Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
J Phys Chem A. 2012 Oct 11;116(40):9872-7. doi: 10.1021/jp306261k. Epub 2012 Sep 27.
Mechanoanions were produced by heterogeneous scission of the glycosidic linkages of the main chain of bacterial cellulose (BC); scission was induced by mechanical fracture of the BC in a vacuum in the dark at 77 K. The mechanoanions were detected using electron-spin-trapping methods with tetracyanoethylene. The yield of mechanoanions was positively correlated with the absolute value of the change in the Mulliken atomic charge, which was used as a descriptor of the ionic nature of the glycosidic linkage. Homogeneous scission of the glycosidic linkages induced by mechanical fracture generated mechanoradicals, the electron affinity of which was estimated on the basis of the energy of the lowest unoccupied molecular orbital for the model structure of the mechanoradical. It was concluded that the electrostatic charging of BC is caused by electron transfer from mechanoanions to mechanoradicals, which have high electron affinities. The electrostatic charge density of BC in a vacuum in the dark at 77 K was estimated to be 6.00 × 10(-1) C/g.
机械阴离子是通过细菌纤维素 (BC) 主链糖苷键的不均匀断裂产生的；在 77 K 的真空中，通过在黑暗中对 BC 进行机械断裂来诱导断裂。使用带有四氰乙烯的电子自旋捕获方法检测机械阴离子。机械阴离子的产率与 Mulliken 原子电荷绝对值呈正相关，Mulliken 原子电荷绝对值可用作糖苷键离子性质的描述符。机械断裂诱导的糖苷键均匀断裂生成机械自由基，其电子亲合能基于机械自由基模型结构的最低未占据分子轨道能量进行估算。得出结论，BC 的静电充电是由机械阴离子向具有高电子亲合能的机械自由基的电子转移引起的。在 77 K 的真空中黑暗中，BC 的静电电荷密度估计为 6.00×10(-1) C/g。
