Experimental and theoretical investigation of the substitution effects on N-substituted carbazole derivatives functionalized with azomethine bonds

Examining the structural, spectroscopic, and electronic properties of molecules using both theoretical and experimental methods allow to reveal their structure-property relationship. In this study, the structural and electrochemical properties of the newly synthesized N-substituted carbazole monomers with aniline (ACA), p- methylaniline (ACMA) and pentafloroaniline (ACFA) by using a combination of experimental and computational methods have been comparatively presented. Theoretically optimized molecular structures of newly synthesized monomers have been determined by Density Functional Theory (DFT) method with 6-31G(d,p) basis set. The structural, spectroscopic, and electronic characterizations of monomers have been performed by various techniques including H-1 NMR, FT-IR, and UV-Visible spectroscopy. Electrochemical polymerizations of monomers were carried out in a 0.1 M LiClO4/DCM/ACN (5:95, V: V) system. Compared to other monomers, the substitution of fluorine atoms has led to an anodic shift of the oxidation potential of the ACFA. Electrochemical and electrochromic properties of the obtained conductive polymers have been comparatively investigated by cyclic voltammetry and spectroelectrochemistry techniques. It has been observed that the poly(E)-N-(4-(9H-carbazol-9-yl) benzylidene) aniline (PACA) polymer film shows higher optical contrast, fast response time, and good electrochemical stability compared to the poly (E) -N - (4-(9H-carbazol-9-yl) benzylidene) -4-methylaniline (PACMA) polymer film.