Electrochromism based on the charge transfer process in a ferrocene–BODIPY molecule

A new type of donor–acceptor molecule DiFc-B combined ferrocene and BODIPY unit has been synthesized, and the NMR spectra, photophysical property, and electrochemical property were studied. The in situ spectro-electrochemical experiment was carried out, a notable absorption change had been observed under oxidative potential, and a recovery could happen under reductive potential and this process could repeat for several times. Such a phenomenon also happened when oxidative metal ion was added into the solution of DiFc-B. In order to study the mechanism of the electrochromism, the theoretical calculation was performed, and the result shows a D (ferrocene)–π–A (BODIPY) system. The energy gap between the HOMO and LUMO had a good consistence with the electrochemical experiment and UV–vis data. The calculation of the frontier orbital belonging to the cation state of DiFc-B shows the directional change of the D–π–A system, which supplied a theoretical basis of the electrochromism.