Synthesis and optical properties of redox-active triphenylamine-based derivatives with methoxy protecting groups

A series of novel redox-active triphenylamine-based materials, 4,4′-bis(4,4′-dimethoxydiphenylaminyl)-4′′-methoxytriphenylamine ( BDATPA ) and four related derivatives, including tris(4-methoxyphenyl)amine ( TPA ), N , N , N ′, N ′-tetrakis(4-methoxyphenyl)-1,4-phenylenediamine ( TPPA ), N , N , N ′, N ′-tetrakis(4-methoxyphenyl)-1,1′-biphenyl-4,4′-diamine ( TPB ) and tris(4-(4,4′-dimethoxyphenylaminyl)phenyl)amine ( TPAPA ), were readily prepared and their electrochemical, photoluminescence (PL) and electrochromic (EC) behaviors were investigated. Interestingly, only TPB exhibited high PL intensities in both solution and solid state, while the others revealed a much lower PL intensity in solution. All of these electroactive materials showed excellent electrochemical reversibility by cyclic voltammetry scanning with multi-color changes at the related oxidation states. Furthermore, UV-Vis and spectroelectrochemical measurements were also applied to evaluate and calculate the molar extinction coefficients in order to facilitate these materials as a color palette.