Location recognition in molecular-scale provides valuable information on positional relationship, absolute conformation and dynamics of molecules. This information is critical to elucidate biological processes and understanding the nature of functional molecular materials. In this study, we present a novel molecular location sensing approach based on an endohedral metallofullerene, Ce@C82, using its anisotropic magnetic properties which lead to temperature-dependent paramagnetic shifts in 1H-NMR spectra (Figure). Endohedral metallofullerenes are promising nano-materials including that for spatial location recognition, because the caged metal is uniquely isolated from the outer environment and rarely escapes from the fullerene cage even in extreme conditions, such as strongly acidic media and high temperature. Such stability makes them the preferred molecular probes in a variety of materials ranging from biological systems to industrial chemicals. In this study, to achieve the concept of location recognition by an endohedral metallofullerene, five site-isomers of Ce@C82CH2-3,5-C6H3Me2 (1a-e) were chemically synthesized by a radical coupling reaction. The temperature-dependent shifts, which are induced by the magnetic anisotropy of the caged Ce, in 1H-NMR spectra of the isomers were clearly characterized by means of experimental molecular structural analysis and theoretical calculations using density functional theory. Detailed numerical analysis of the shifts using suitable statistic criteria successfully located the relative position of the nearby hydrogen atoms from the inside Ce atom. These results evidenced that the paramagnetic shifts based on the anisotropic magnetism of the encapsulated metal atom can be used for molecular location recognition.

Anisotropic magnetic properties of an endohedral metallofullerene for molecular location sensing

256th National Meeting (2018)

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