Novel chiral PEDOTs for selective recognition of 3,4-dihydroxyphenylalanine enantiomers: synthesis and characterization

Two new 3,4-ethylenedioxythiophene (EDOT) derivatives, (2R)-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl 2-phenylpropanoate ((R)-EDTM-PP) and (2S)-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl 2-phenylpropanoate ((S)-EDTM-PP), were synthesized and electropolymerized in dichloromethane (CH₂Cl₂) and terabutylammonium hexafluorophosphate (Bu₄NPF₆) system. As chiral electrodes, poly((2R)-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl 2-phenylpropanoate) ((R)-PEDTM-PP) and poly((2S)-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methyl 2-phenylpropanoate) ((S)-PEDTM-PP)-modified glassy carbon electrodes (GCEs) were employed to successfully recognize 3,4-dihydroxyphenylalanine (DOPA) enantiomers. Cyclic voltammetry presents that (R)-PEDTM-PP and (S)-PEDTM-PP had good redox activity and stability. Spectroelectrochemistry studies revealed (R)-PEDTM-PP and (S)-PEDTM-PP polymers have electronic bandgap of 1.68 and 1.66 eV, and could be reversibly oxidized and reduced accompanying with obvious color changes from dark blue to light purple. In addition, the electrochemical behavior, structural characterization, thermal stability, morphology and circular dichroism of (R)-PEDTM-PP and (S)-PEDTM-PP films were investigated in detail.