Interaction strength in molecular junctions consisting of π-stacked antiaromatic molecules

Abstract

Elucidation of intermolecular interactions is essential for understanding charge transport properties in organic materials and organic electronic devices. While interactions between aromatic molecules have been extensively studied, little is known about interactions between antiaromatic molecules. Theoretical considerations predict that when two antiaromatic porphyrin molecules are superimposed, the antiaromatic molecules should be stabilized by attractive intermolecular interactions. In this study, we used atomic force microscopy to evaluate intermolecular interactions originating from the π–π stacking of the two antiaromatic porphyrin moieties at the molecular level. We evaluated substantial interaction between the antiaromatic porphyrin moieties as an adhesion force of the antiaromatic porphyrin molecular pairs using force spectroscopy. The present result supports the formation of π–π stacking due to the attractive interaction between the two antiaromatic π-systems at the single-molecule level.