@article { ISI:000294146400020,
	title = {Isotopic Hydration of Cellobiose: Vibrational Spectroscopy and Dynamical Simulations},
	journal = {JOURNAL OF PHYSICAL CHEMISTRY A},
	volume = {115},
	year = {2011},
	month = {SEP 1},
	pages = {9498-9509},
	abstract = {The conformation and structural dynamics of cellobiose, one of the fundamental building blocks in nature, its C4{\textquoteright} epimer, lactose, and their microhydrated complexes, isolated in the gas phase, have been explored through a combination of experiment and theory. Their structures at low temperature have been determined through double resonance, IR-UV vibrational spectroscopy conducted under molecular beam conditions, substituting D2O for H2O to separate isotopically, the carbohydrate (OH) bands from the hydration (OD) bands. Car-Parrinello (CP2K) simulations, employing dispersion corrected density functional potentials and conducted {\textquoteleft}{\textquoteleft}on-the-fly{\textquoteright}{\textquoteright} from similar to{\textendash}{\textquoteright}20 to similar to 300 K., have been used to explore the consequences of raising the temperature. Comparisons between the experimental data, an harmonic vibrational self-consistent field calculations based upon ab initio potentials, and the CP2K simulations have established the role of anharmonicity; the reliability of classical molecular dynamics predictions of the vibrational spectra of carbohydrates and the accuracy of the dispersion corrected (BLYP-D) force fields employed; the structural consequences of increasing hydration; and the dynamical consequences of increasing temperature. The isolated and hydrated cellobiose and lactose units both present remarkably rigid structures: their glycosidic linkages adopt a {\textquoteleft}{\textquoteleft}cis{\textquoteright}{\textquoteright} (anti-phi and syn-psi) conformation bound by inter-ring hydrogen bonds. This conformation is maintained when the temperature is increased to similar to 300 K and it continues to continus to be maintained when the cellobiose(or lactose) unit is hydrated by one or two explicitly bound water molecules. Despite individual-fluctuations in the intra- and intermolecular hydrogen bonding pattern and some local structural motions, the water molecules remain locally bound and the isolated carbohydrates remain trapped within the cis potential well. The Car-Parrinello dynamical simulations do not suggest any accessible pathway to the trans conformations that are formed in aqueous solution and are widespread in nature.},
	issn = {1089-5639},
	doi = {10.1021/jp112109p},
	author = {Pincu, Madeleine and Cocinero, Emilio J. and Mayorkas, Nitzan and Brauer, Brina and Davis, Benjamin G. and R Benny Gerber and Simons, John P.}
}
