Water Sentenced To Solitary Confinement In Carbon Cage

Using chemical synthesis to set and spring a molecular trap, researchers in Japan captured a lone water molecule inside a C₆₀ fullerene cage (Science, DOI: 10.1126/science.1206376). The molecule, H₂O@C₆₀ (shown), gives scientists an opportunity to study water in isolation, without the influence of the hydrogen-bonded network in which it usually exists. Kyoto University’s Yasujiro Murata and Kei Kurotobi created H₂O@C₆₀ via a “surgical” approach. They took C₆₀ and, through a series of chemical transformations, poked a hole in it large enough to accommodate a water molecule. To lure the polar water molecule into the interior of the hydrophobic cage, they used reactions that generated hydrophilic carbonyl and hydroxyl groups at the rim of the opening. Murata and Kurotobi ultimately ensnared the water molecule by heating the perforated cage with water at 120 °C under 9,000 atm of pressure for 36 hours. They then used chemical synthesis to stitch the fullerene back up. “As the next research step, we need to study the influence of the encapsulated water toward the physical properties and chemical reactivity of the outer C₆₀ cage,” Murata tells C&EN.