Comparing Crystallizations in Three Dimensions and Two Dimensions: Behavior of Isomers of [2,2′-Bipyridine]dicarbonitrile and [1,10-Phenanthroline]dicarbonitrile

Abstract

Various symmetric isomers of [2,2′-bipyridine]dicarbonitrile and [1,10-phenanthroline]dicarbonitrile were crystallized from solution and also deposited as monolayers adsorbed on graphite. The resulting three- and two-dimensional (3D and 2D) structures were studied by single-crystal X-ray diffraction and scanning tunneling microscopy, respectively. Previous comparisons of 3D and 2D structures have provided new understanding of molecular organization and have revealed that crystals and adlayers can have closely analogous structures despite the effects of the underlying surface, especially when organization is dominated by strong intermolecular interactions within a single plane. The present study extends previous work by showing that analogous 3D and 2D structures can be formed even when association is directed by weaker intermolecular forces, as exemplified by C–H···N interactions of nitriles.