Carbohydrate–aromatic interactions: A computational and IR spectroscopic investigation of the complex, methyl α-l-fucopyranoside · toluene, isolated in the gas phase

A carbohydrate–aromatic complex, methyl α-l-fucopyranoside · toluene, which provides a model for probing the physical basis of carbohydrate–protein ‘stacking’ interactions, has been created in a molecular beam and probed through IR ion dip spectroscopy in the CH and OH regions. The results are interpreted in the light of DFT calculations using the MO5-2X functional. They indicate the creation of stacked structures with the aromatic molecule bonded either to the upper or to the lower face of the pyranoside ring, through CH3,4–π (upper) or CH1–π (lower) interactions leading to binding energies ⩽18 kJ mol−1.