Synthesis of a distinct water dimer inside fullerene C70.
The water dimer is an ideal chemical species with which to study hydrogen bonds. Owing to the equilibrium between the monomer and oligomer structure, however, selective generation and separation of a genuine water dimer has not yet been achieved. Here, we report a synthetic strategy that leads to the successful encapsulation of one or two water molecules inside fullerene C70. These endohedral C70 compounds offer the opportunity to study the intrinsic properties of a single water molecule without any hydrogen bonding, as well as an isolated water dimer with a single hydrogen bond between the two molecules. The unambiguously determined off-centre position of water in (H2O)2@C70 by X-ray diffraction provides insights into the formation of (H2O)2@C70. Subsequently, the (1)H NMR spectroscopic measurements for (H2O)2@C70 confirmed the formation of a single hydrogen bond rapidly interchanging between the encapsulated water dimer. Our theoretical calculations revealed a peculiar cis-linear conformation of the dimer resulting from confinement effects inside C70.
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Rui
R
Zhang
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Michihisa
M
Murata
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Tomoko
T
Aharen
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Atsushi
A
Wakamiya
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Takafumi
T
Shimoaka
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
Takeshi
T
Hasegawa
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.|JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
Yasujiro
Y
Murata