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–π-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.