Synthesis and characterization of chiral PEDOT enantiomers bearing chiral moieties in side chains: chiral recognition and its mechanism using electrochemical sensing technology

Abstract

In this work, we present a pair of chiral PEDOT derivatives named poly((R)-2-(chloromethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine) ((R)-PEDTC) and poly((S)-2-(chloromethyl)-2,3-dihydrothieno[3,4-b][1,4]dioxine) ((S)-PEDTC), which were employed as excellent chiral recognition materials for fabricating chiral sensors and then discriminating between 3,4-dihydroxyphenylalanine (DOPA) enantiomers. Importantly, the mechanism of the stereospecificity of the interaction between the DOPA enantiomers and chiral polymers was discussed specifically. A series of performances of corresponding polymers were characterized in some detail using different strategies including CV, CD, FT-IR, UV-vis, SEM, and TG. The CD spectrum indicated that (R)-PEDTC and (S)-PEDTC are mirror symmetric. CV shows that the polymers had superior redox reversibility in CH₃CN–Bu₄NPF₆. Finally, different electrochemical methods including CV, square wave voltammetry (SWV) and differential pulse voltammetry (DPV) were introduced for the discrimination of DOPA enantiomers. Satisfactory measurement results demonstrated that (R)-PEDTC/GCE and (S)-PEDTC/GCE exhibited excellent enantioselectivity of DOPA enantiomers and the tendency was for anisotropic interaction between (R)-PEDTC and L-DOPA, and (S)-PEDTC and D-DOPA. This implied that the obtained polymer films could be promising candidates as enantioselective materials in the electrochemical sensor field.