Zhao Chong, Nie Mingzhe, Meng Haibing, Wang Chunru, Wang Taishan
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructure and Nanotechnology , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
Inorg Chem. 2019 Jun 17;58(12):8162-8168. doi: 10.1021/acs.inorgchem.9b00954. Epub 2019 May 24.
We synthesized and isolated two paramagnetic metallofullerenes of La@C and Y@C with different fullerene cages, which were characterized by electron paramagnetic resonance (EPR) spectroscopy and theoretical calculations. DFT calculations disclosed two possible isomers of La/Y@C with C- C and C- C cages, both of which have similar thermodynamic stability and one pair of fused pentagons. Their paramagnetic properties were then studied by EPR spectroscopy, and the obtained EPR signals were analyzed with very different hyperfine coupling constants, revealing distinct electron spin distributions for these two species. Furthermore, the experimental coupling constants were compared with those of calculated coupling constants, and comparison results revealed that the produced La@C has a C- C cage and Y@C has a C- C cage. These studies illustrate that the electron spin can be used as a probe to identify metallofullerene structure due to the susceptibility of spin-metal couplings. The successful isolation and characterizations of La@C and Y@C with such a small C cage reveal their stability that is important for application as paramagnetic molecule materials.
我们合成并分离出了两种具有不同富勒烯笼的镧内嵌富勒烯（La@C）和钇内嵌富勒烯（Y@C）顺磁性金属富勒烯，通过电子顺磁共振（EPR）光谱和理论计算对其进行了表征。密度泛函理论（DFT）计算揭示了具有C - C和C - C笼的La/Y@C的两种可能异构体，二者具有相似的热力学稳定性且都有一对稠合五边形。然后通过EPR光谱研究了它们的顺磁性质，并对获得的EPR信号进行了分析，其超精细耦合常数差异很大，揭示了这两种物质不同的电子自旋分布。此外，将实验耦合常数与计算耦合常数进行了比较，比较结果表明所制备的La@C具有C - C笼，Y@C具有C - C笼。这些研究表明，由于自旋 - 金属耦合的敏感性，电子自旋可作为识别金属富勒烯结构的探针。如此小的C笼的La@C和Y@C的成功分离与表征揭示了它们的稳定性，这对于作为顺磁性分子材料的应用很重要。
