Qualitative Insights into the Transport Properties of Hückel/Möbius (Anti)Aromatic Compounds: Application to Expanded Porphyrins

Abstract

Expanded porphyrins have been recently identified as promising candidates for conductance switching based on aromaticity and molecular topology changes. However, the factors that control electron transport switching across the metal–molecule–metal junction still need to be elucidated. For this reason, the transport properties of Huckel/Mobius (anti)aromatic compounds are investigated thoroughly in this work to gain qualitative understanding into the conductivity of these unique macrocycles. Starting from a polyene model, a simple counting rule is developed to predict the occurrence of quantum interference around the Fermi level at the Huckel level of theory. Next, the different approximations of Huckel theory are lifted, enabling the exploration of the influence of each of these approximations on the transport properties of expanded porphyrins. Along the way, a detailed study on the relationship between the conductance and aromaticity/topology has been undertaken. Even though it has been proposed that the...