Molecular recognition properties of crown ether-functionalized oligothiophenes

The palladium-catalyzed cross-coupling of dibrominated thieno-crown ethers and stannylated cyclohexyl-capped mono- or bithiophenes leads to novel end-capped oligothiophenes functionalized with crown ether units of different ring size which are directly linked to the oligomeric π-system. The electrochemical properties of these oligomers have been investigated in the presence of metal cations. Their redox chemistry is strongly influenced by the molecular recognition process and by the polarity of the solvent system. Due to electrostatic interactions between the complexed cation and the redox center, the oxidation of the oligothiophene π-system becomes more difficult leading to an anodic shift of the oxidation potential.