Sugars in the gas phase: the spectroscopy and structure of jet-cooled phenyl β-D-glucopyranoside

The first spectroscopic investigation and full structural assignment of a model glycoside in the gas phase, namely phenyl β-D-glucopyranoside, is reported, based upon measurements of its resonant two photon ionisation and infra-red ion dip spectra together with supporting ab initio calculations. Three conformers (two gauche and one trans) were identified and structurally assigned. A comparison with the predictions of earlier high-level ab initio calculations on the unsubstituted sugar, indicate that the addition of a phenyl substituent at position 1 on the pyranoside ring, has very little effect on the low energy region of its conformational landscape.