Electrochemical polymerisation of thiophene derivative induced by Lewis acid: Electrosynthesis of poly[(R)-(−)-2-(3′-thienyl)ethyl-(3′,5″-dinitrobenzoyl)-α-phenylglycinate]

Films of poly(R)-(−)-2-(3′-thienyl)ethyl-(3′,5″-dinitrobenzoyl)-α-phenylglycinate] were deposited on ITO electrodes by potentiodynamic, potentiostatic and galvanostatic methods using a (C₄H₉)₄NBF₄/CH₃CN electrolyte system containing 20% boron trifluoride diethyl etherate. Polymerisation occurred as a charge dependent process at a potential of 1.4 V vs. Ag/Ag⁺(CH₃CN). The surface morphologies of the films so-formed were examined using atomic force microscopy. The film deposited by the galvanostatic method displayed more homogeneous grain geometry and a larger superficial area than those formed by the other methods. Cyclic voltammetry revealed a well defined redox couple at the anodic region, attributable to polymer p-doping, and a poorly defined redox pair at the cathodic region, attributable to the reduction of the nitro group. The polymeric films obtained were yellow in colour (λ_max 425 nm) in the reduced state and light blue (λ_max 745 nm) in the oxidised state.