Electrochromic and electrochemical properties of 3-pyridinyl and 1,10-phenanthroline bearing poly(2,5-di(2-thienyl)-1H-pyrrole) derivatives

This study examined a highly efficient synthetic route and characterization of two derivatives of 2,5-di(2-thienyl)-1H-pyrrole that incorporated 3-pyridinyl and 1,10-phenanthroline moieties in the central pyrrole ring. The electrically conductive polyPTPy and polyPhenTPy films were synthesized through electropolymerization on a glassy carbon electrode in a 0.1 M TBAP/dichloromethane solution. The polymer films were characterized using cyclic voltammetry (CV), in situ conductivity measurements, and in situ spectroelectrochemistry. The redox peaks of the polyPTPy and polyPhenTPy films were observed at 0.96/0.66 and 0.89/0.73 V, respectively. The maximum conductivities of polyPTPy and polyPhenTPy were 6.5×10−2 and 9.2×10−2 S/cm at 1.4 V. The spectroelectrochemical analysis showed that the polyPTPy film was brownish-yellow color (λmax=430 nm) in the neutral state and dark blue (1.4 V) in the fully oxidized state. Similarly, polyPhenTPy was greenish-yellow color (λmax=451 nm) in the neutral state and light blue (1.4 V) in the fully oxidized state. The polymer films exhibited a fast optical switching time within 1.0 s. The electrochemical and spectroelectrochemical characterizations of these films revealed that the materials were highly electroactive and robust in terms of electrochromics.