A high resolution electron energy loss spectroscopy study of the adsorption of benzylic amide macrocycle on Au(111)

The adsorption from the gas phase of a macrocyclic molecule composed of benzylic amide (–CONH–CH2–C6H4–) groups on Au(1 1 1) at 300 K has been studied using high resolution electron energy loss spectroscopy. The film order and vibrational properties were explored as a function of coverage, method of adlayer deposition and annealing. Beyond a critical coverage, a template effect strongly influences the macrocycle’s orientation with respect to the substrate. In the case of ordered films (domain size>80 Å), the intensity of the out-of-plane C–H deformation mode relative to the in-plane C–H stretch indicates that an adsorption geometry with the plane of the phenyl rings largely parallel to the Au(1 1 1) surface is favoured in the submonolayer to monolayer coverage regime. Upon consideration of solid state X-ray diffraction data, this flat-lying molecular orientation, which is accompanied by chemisorption via the carbonyl function, must involve considerable distortion of the adsorbed macrocycle from its crystal structure.