A crown-ether loop-derivatized oligothiophene doubly attached on gold surface as cation-binding switchable molecular junction

A crown-ether dithiol quaterthiophene is synthesized and immobilized on gold surface by double covalent fixation. UV-vis spectroscopy and cyclic voltammetry show that the corresponding dithioester precursor can complex Pb2+ in solution and that this property is maintained for monolayers of the dithiol on gold. Current-voltage measurements by eutectic GaIn drop contact on the monolayer show a significant increase (up to 1.6 × 10 3 times) of the current at low bias after Pb2+ complexation.