本文研究了(C_(60))_2-[P(O)(OCH_3)]_2富勒烯双体内的笼间C―C键的热力学性质(该双体的结构详见文献,Chem.Commun.2011,47,6111)。原位、变温电子顺磁共振波谱实验结果表明,该C―C键的键离解能(BDE)为72.4 k J?mol^(-1)(17.3 kcal?mol^(-1)),仅约为常见氢键的两倍,或约为常见有机C―C键的五分之一。因此,该二聚体于较高温度时容易发生均裂反应,形成单体自由基;降温时又容易发生自由基聚合反应。基于该笼间C―C键所具有的这些热力学特性,我们对其可被用于制备有序的富勒烯分子元器件等材料作展开讨论。
The formation and qualification of redox sites in transition metal oxides are always the active fields related to electronics, catalysis, sensors, and energy-storage units. In the present study, the temperature dependence of thermal reduction of MoO3 was surveyed at the range of 350℃ to 750℃. Upon reduction, the formed redox species characterized by EPR spectroscopy are the MoVion and superoxide anion radical (O2-) when the reduction was induced at the optimal temperature of 300-350℃. When heating-up from 350℃, the EPR signals started to decline in amplitude. The signals in the range of 400-450℃ decreased to half of that at 350℃, and then to zero at ~600℃. Further treatment at even higher temperature or prolonged heating time at 500℃ caused more reduction and more free electrons were released to the MoO3 bulk, which results in a delocalized means similar to the antiferromagnetic coupling. These data herein are helpful to prepare and study the metal-oxide catalysts.
