A Crown-Ether Loop-Derivatized Oligothiophene Doubly Attached on Gold Surface as Cation-Binding Switchable Molecular Junction

TL;DR

This study synthesizes a crown-ether functionalized oligothiophene for covalent attachment on gold, demonstrating its ability to bind Pb2+ ions and switch its electrical conductance significantly upon complexation, useful for molecular sensing.

Contribution

It introduces a novel crown-ether loop-derivatized oligothiophene molecule with double gold surface attachment, showing its cation-binding and switchable conductance properties.

Findings

Pb2+ complexation maintains in monolayers on gold

Significant increase in current upon Pb2+ binding

Potential application in molecular sensing

Abstract

A crown-ether dithiol quaterthiophene is synthesized for its covalent immobilization by double fixation on gold surface. While the corresponding dithioester precursor exhibits Pb2+ complexation properties in solution as evidenced by UV-vis spectroscopy and cyclic voltammetry, this Pb2+ affinity is still maintained for monolayers of the dithiol on gold. In addition, current-voltage measurements by Eutectic GaIn drop contact on the monolayer show a significant increase (up to 1.6 x 1E3) of the current at low bias after Pb2+ complexation.