Hindered Rotation of Water near C60

Cross-polarization (CP) nuclear magnetic resonance experiments show that water within about 1 nm of C60 molecules is anisotropic and undergoes rotational motion that is greatly hindered compared with motion in bulk. The experimental observation of a Hartmann−Hahn CP contact shows that the motion of water is slow enough for intermolecular 1H (water)−13C (C60) dipolar coupling to occur, suggesting that the time scale of the rotational (tumbling) motion of the water adjacent to the C60 is slower than the microsecond range. This is much slower than the picosecond range previously observed for bulk water. The dipolar coupling decreases with temperature in the range of 3−22 °C. This work provides molecular-scale evidence that a small hydrophobic particle can order surrounding liquid water molecules.