Antiaromatic non-alternant heterocyclic compounds as molecular wires

Abstract

We have theoretically studied the electron-transport properties of a family of molecular junctions containing the non-alternant antiaromatic pentalene moiety stabilised with various 5-membered heterocycles. For this purpose, we used a combination of density functional theory and Green's function techniques. We have focussed on dithieno derivatives to understand if the relative position of the heteroatom influences the transport properties as significantly as it does the degree of antiaromaticity. We found that the heteroatom position does significantly affect the shape of the transmission curves, but there is no correlation between the degree of antiaromaticity and the magnitude of the transmission at the Fermi level. Overall, we find that this behaviour is well-modelled by tight-binding calculations and the graphical prediction scheme. On the other hand, curly arrow rules fail for certain isomers, regardless of the degree of antiaromaticity. Reasons for this discrepancy are discussed.