Synthesis and properties of new 9,10-anthraquinone derived compounds for molecular electronics

Fourteen new derivatives of 9,10-anthraquinone or 9,10-dimethoxyanthracene were designed, synthesised and characterised. Regarding the structure, the compounds are pi-conjugated (cross and linear, respectively) and feature thiophene terminated side arms attached to five different positions of the anthraquinone or anthracene core. The synthesis of the compounds involves a cross-coupling procedure in the key reaction steps. Crystal structures of compounds 5 and 19 have been studied. The thiophene containing title compounds 1-5 can be reduced and oxidised by a two step redox process. The electrochemical parameters have been analysed by cyclic voltammetry (CV). Theoretical calculations in the framework of all-electron density functional theory (DFT) were used to investigate the electronic structure of the individual free molecules. Furthermore, calculations of the transport properties of model devices containing compounds 1-3 and respective reduced hydroquinone derivatives assembled at Au(111) electrodes were carried out to evaluate their potential for the application as redox-active switches.