Molecular Location Sensing Approach by Anisotropic Magnetism of an Endohedral Metallofullerene.
Location recognition at the molecular scale provides valuable information about the nature of functional molecular materials. This study presents a novel location sensing approach based on an endohedral metallofullerene, Ce@C82, using its anisotropic magnetic properties, which lead to temperature-dependent paramagnetic shifts in (1)H NMR spectra. Five site-isomers of Ce@C82CH2-3,5-C6H3Me2 were synthesized to demonstrate the spatial sensing ability of Ce@C82. Single-crystal structures, absorption spectra, and density functional theory calculations were used to select the plausible addition positions in the radical coupling reaction, which preferentially happens on the carbon atoms with high electron density of the singly occupied molecular orbital (SOMO) and positive charge. Temperature-dependent NMR measurements demonstrated unique paramagnetic shifts of the (1)H peaks, which were derived from the anisotropic magnetism of the f-electron in the Ce atom of the isomers. It was found that the magnetic anisotropy axes can be easily predicted by theoretical calculations using the Gaussian 09 package. Further analysis revealed that the temperature-dependent trend in the shifts is clearly predictable from the distance and relative position of the proton from the Ce atom. Hence, the Ce-encapsulated metallofullerene Ce@C82 can provide spatial location information about nearby atoms through the temperature-dependent paramagnetic shifts of its NMR signals. It can act as a molecular probe for location sensing by utilizing the anisotropic magnetism of the encapsulated Ce atom. The potentially low toxicity and stability of the endohedral fullerene would make Ce@C82 suitable for applications in biology and material science.
Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Sakyo-ku, Kyoto 606-8501, Japan.
Yuta
Y
Takano
Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba , Tsukuba, Ibaraki 305-8577, Japan.
Ryo
R
Tashita
Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba , Tsukuba, Ibaraki 305-8577, Japan.|Department of Chemistry, Tokyo Gakugei University , Tokyo 184-8501, Japan.
Mitsuaki
M
Suzuki
Fukui Institute for Fundamental Chemistry, Kyoto University , Sakyo-ku, Kyoto 606-8103, Japan.
Shigeru
S
Nagase
Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University , Sakyo-ku, Kyoto 606-8501, Japan.|Department of Molecular Engineering, Graduate School of Engineering, Kyoto University , Nishikyo-ku, Kyoto 615-8510, Japan.
Hiroshi
H
Imahori
Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba , Tsukuba, Ibaraki 305-8577, Japan.|Department of Chemistry, Tokyo Gakugei University , Tokyo 184-8501, Japan.|State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Technology, Huazhong University of Science and Technology , Wuhan 430074, China.|Foundation for Advancement of International Science , Tsukuba, Ibaraki 305-0821, Japan.
Takeshi
T
Akasaka