A carbohydrate- aromatic complex, methyl alpha-L-fucopyranoside center dot 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-pi (upper) or CH1-pi (lower) interactions leading to binding energies <= 18 kJ mol(-1). (C) 2009 Elsevier B.V. All rights reserved.