Self-Standing Membranes Consisting of Inherently Chiral Electroactive Oligomers: Electrosynthesis, Characterization and Preliminary Tests in Potentiometric Setups

Self-standing chiral electroactive synthetic membranes are presented, prepared by oxidative electro-oligomerization of a thiophene-based "inherently chiral" electroactive monomer on indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) electrodes, followed by detachment of the electrodeposited thin films in aqueous solution. The membranes, possibly mesoporous, consist of a mixture of open and cyclic "inherently chiral" oligomers, that is, in which both chirality and electroactivity originate from the same source, and this is the main conjugated backbone featuring a tailored torsion. Such a combination can afford outstanding chirality manifestations. The electrosynthesis conditions significantly modulate the oligomer distribution. Racemate films are compared to enantiopure ones. Circular dichroism confirms that (R)- or (S)- enantiopure films are obtained, starting from the corresponding (R)- or (S)- enantiopure monomers. Reliable transmembrane potential readings are obtained in preliminary tests in ion-selective electrode (ISE)-like setups, consistent with those predicted considering the membrane features, offering a first step towards extension of the protocol to chiral experiments.