| Popis: |
Electrochromic systems are compounds which modify their optical behaviours (their colour) through electrical voltage together with a redox-reaction. Such electrochromic systems are used in the display und shutter technology (ECD). Besides the special built polymers and nitrogenous compounds, oligomers e.g. poly-alkoxyaromats (fluorens and triphenyls) as electrochromic systems are treated with special interest in organic chemistry. We tried to synthesize fluoren and triphenyl compounds and to examine their electrochemical and electrochromic characteristics with the help of cyclovoltammetry. 2,3-bis(3,4-dimethoxyphenyl)-1,3-butadien had undergone a Diels-alder-reaction with acetylendicarbonaciddimethylester, -diethylester, di-t-butylester und -diphenylester. After aromatising dicarbonaciddialkylester compounds were obtained through 2,3-dichlor-5,6-dicyanquinon (DDQ). Comparative cyclovoltammetric studies of those compounds allowed the determination of their oxidationpotentials and furthermore confirmed the mechanism of the oxidative intramolecular ringclosure for the formation of the triphenylen compounds. The potential-controlled electrolysis of these terphenyldiaciddialkylesters for the formation of the push-pull-triphenylensystems was executed in a specially made undivided cell with three-electrode arrangement. Cyclovoltammetric studies were carried out at the new push-pull-triphenylen compounds. It could be shown that a relatively high stability of electrochemical equilibrium exists between these compounds and their radical cations. Methyl-, ethyl and t-butylreste of the groups of carbonicacidesters seem to exert hardly any influence on the push-pull-systems. Further special investigations are needed to state the electrochromic properties concerning these push-pull-systems. All solvents, in which those compounds solve completely or partially, showed different colours. Furthermore an intensive blue fluorescence was observed under UV-irradiation with 254 nm. The clearing-up of the crystal structure of the push-pull-triphenylendimethylester derivative succeeded. |
