Thioether-Functionalized Quinone-Based Resorcin[4]arene Cavitands: Electroswitchable Molecular Actuators

The utility of molecular actuators in nanoelectronics requires activation of mechanical motion by electric charge at the interface with conductive surfaces. We functionalized redox-active resorcin[4]arene-quinone cavitands with thioethers as surface-anchoring groups at the lower rim and investigated their propensity to act as electroswitchable actuators that can adopt two different conformations in response to changes in applied potential. Molecular design was assessed by DFT calculations and X-ray analysis. Electronic properties were experimentally studied in solution and thin films electrochemically, as well as by X-ray photoelectron spectroscopy on gold substrates. The redox interconversion between the oxidized (quinone, Q) and the reduced (semiquinone, SQ) state was monitored by UV-Vis-NIR spectroelectrochemistry and EPR spectroscopy. Reduction to the SQ state induces a conformational change, providing the basis for potential voltage-controlled molecular actuating devices.