Multi-mode chemical transducers. Part 2. Electrochromic and photochromic properties of azoquinone compounds

Abstract

Several molecules having multiple regions independently responsive to stimulations have been investigated. A 2-(4-methoxyphenylazo)anthraquinone (1) having both an electrochromic quinone group and a photochromic azo group has been synthesized and its electrochromic and photochromic properties investigated. It shows interconversion of four distinct states caused by multiplication of two electrochromic redox states, quinone and hydroquinone, and two photochromic geometrical isomers, anti and syn forms. Moreover the syn-anti thermal isomerization rate of the azo region of the molecule is dependent on the state of the electrochromic quinone region. The rate for the quinone form is more than 30 times faster than that of the hydroquinone form. Additionally three other azoquinone compounds have been synthesized and investigated in the same way. The results show that these molecules have functions of multiple responsibilities for distinguishable stimulations as multi-mode chemical signal transducers.