Surface confined reaction of aliphatic diamines with aromatic diisocyanates on Au{111} leads to ordered oligomer assemblies

The surface-confined reaction of 1,4-diaminobutane with 1,3- and 1,4-phenylene diisocyanate on Au{111} was investigated by scanning tunnelling microscopy in ultrahigh vacuum. For both the m- and p-phenylene diisocyanates, the nucleophilic addition reaction to form oligourea species occurred at, or slightly above, 300 K. Subsequent annealing allows oligomers to form extended ordered assemblies that density functional theory reveals are stabilized by intermolecular H-bonding interactions.