Aromaticity switches: from chemical design to single-molecule electronic devices

Description

Creating functional nanoscale devices using single molecules as active electronic components is the ultimate goal of the field of molecular electronics. Besides their potential to meet the growing demand for miniaturization of electronics, appealingly, molecular electronics opens up the possibility of devices with novel, unforeseen functionalities beyond silicon-based technologies, such as molecular switches. The successful implementation of molecular switches in devices requires a fundamental understanding of the numerous factors that control the efficiency of the switch, not only at the single-molecule level but also in the device architecture. To address these challenges, we devised a bottom-up modelling approach in which the fundamental knowledge of the quantum properties of π-conjugated molecules pave the way to the rational design of high-yield molecular switching devices. In this talk, I will describe how computational chemistry can be applied to unveil the factors governing the molecular topology and the properties of expanded porphyrins and how this knowledge can lead to the development of a novel type of molecular switches [1,2].
Beyond the identification of high-performance molecular switches, a central objective is to establish the structure-function relationships in single-molecule optoelectronics. Aromaticity emerged as the key concept determining the electronic, magnetic and nonlinear optical properties of expanded porphyrins and accordingly, we proposed different methods to quantify Hückel and Möbius aromaticity [2,3]. Appealingly, macrocyclic aromaticity determines to a large extent the transmission functions of the different states, so expanded porphyrins could act as efficient three-level conductance switches upon redox and topology interconversions [4]. Further insight about the factors that control the conductance switching across Hückel and Möbius macrocycles was derived from tight-binding Hückel and frontier molecular orbital theory. Overall, a set of qualitative rules to predict the presence of a quantum interference around the Fermi level is provided for both Hückel and Möbius systems [5].

Period	28 May 2018
Event title	Chemical Bonding in the 21st Century: A one day symposium in honor of Professor Roald Hoffmann
Event type	Conference
Location	Brussels, Belgium
Degree of Recognition	International