The concept of the bond polarization is a useful tool to understand chemical reactions and fundamental properties of compounds. However, experimental considerations are limited owing to its difficulty of reliable description. We demonstrated that geometrically isolated H2 O inside the cage of fullerene C60 is a possible probe to evaluate the polarization degree of covalent bonds C(C60 )-X (X=heteroatom) on the C60 cage. The 1 H NMR relaxation times of entrapped H2 O have been systematically measured at variable temperatures for H2 O@C60 X (X=CR2 , NR, O, and O2 ). The results followed in the order of electronegativities of C (2.55), N (3.04), and O (3.44), indicating that entrapped H2 O can sensitively respond to the degree of the bond polarization.
Keywords: NMR spectroscopy; bond polarization; fullerenes; relaxation times; water.
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