Electrochromic 2,4,6-triphenyl-1,3,5-triazine based esters with electron donor-acceptor structure

Ten tripod-shaped electrochromic materials (compound 1-10) were designed and synthesized by esterification of 4,4',4 ''-s-triazine-2,4,6-triyl-tribenzoic acid with different alcohols and phenols. These materials have a 2,4,6-triphenyl-1,3,5-triazine core and three ester side arms, forming an electron donor-pi-acceptor structure. The electrochemical and optical properties of 1-10 were characterized by cyclic voltammetry and ultraviolet-visible spectroelectrochemistry. The conjugated structure of 1-10 markedly influenced their electrochemical properties. Electrochromic devices containing some of these compounds (1, 2, 4, 5, and 10) displayed intense color changes, fast switching times (< 2 s), high optical contrast (> 60%), good switching stability, high optical density (> 1.0), and high coloring efficiency (> 1000 cm(2)C(-1)). The colored state of these devices strongly depended on the conjugated structure of the tripod-shaped component. Short chain lengths (compounds 1 and 2) and electron-donating groups (compounds 4, 5, 8, and 10) were beneficial to electrochromic properties, whereas a longer chain length (compound 3) and electron-withdrawing groups (compounds 6 and 9) adversely affected electrochromic properties.