The role of aromaticity and the π-conjugated framework in multiporphyrinic systems as single-molecule switches

A systematic analysis of electron-transport characteristics for monomer, dimer, and tetramer multiporphyrinic systems is presented, to provide a thorough understanding of the structural dependence of electron transport related to the aromatic nature of the contact structure. Theoretical investigation shows that the electron-transport characteristics can be controlled by manipulating the pi-conjugated framework in the multiporphyrinic systems through the arrangement of the inner hydrogen atoms. The designed pi-conjugated framework assigns the distinct aromaticity on the contact structure, and the large aromatic nature of the contact structure increases conductivity. The feature emerging from this study is that the aromaticity and pi-conjugated framework are important factors that control the electron-transport characteristics in molecular-scale electronic devices, such as single-molecule switches.