Tetsuyuki Saika

A multi-mode chemical transducer 1 new conjugated function of photochromism and electrochromism of azo-quinone compound

Abstract A new class of chemical transducer, azo-quinone (1) shows both electrochromism and photochromism. Moreover, the rate of thermal decay of cis-form was dependent on quinone region.

Cationic polypyrrole composites with anionic functional molecules

Positively charged pyrroles incorporating the quaternized pyridine moiety, [1-methyl-3-(pyrrol-1-ylmethyl)pyridinium chloride, MPP] and [1-(5-pyrrol-3-ylpentyl)pyridinium bromide, PPP], have been synthesized. The polymer of MPP (PMPP), cationic polypyrrole obtained by chemical polymerization and electropolymerization of MPP, is soluble in various polar solvents and displays anion-exchange ability. The amount of the incorporated anionic species in PMPP is ca. five times greater than that in polypyrrole because incorporation is through anodic doping and electrostatic binding with the pyridinium moiety. The PMPP composites with anionic metal complexes and anionic polymers provide films either by the casting method or by the dipping method. These films were also obtained by electropolymerization of MPP in the presence of the anionic functional molecules. The resulting composite-modified electrodes show clear electrochromism (EL) for PMPP/FeBPS and bright electrogenerated chemiluminescence (ECL) for PMPP/RuBPS, respectively. Excellent optical properties are achieved by incorporation of a large amount of the anionic functional molecules and therefore by suppression of undesired background absorption of the PMPP matrix. Another cationic polymer of PPP showed high conductivity (10–2 S cm–1) as well as high-density incorporation of anionic functional molecules.

Thiophene oligomers with a photoswitch

Thiophene oligomers having a dithienylethene structure show large shifts in oxidation potential to the cathodic region in excess of 0.87–1.27 V by photocyclization.

Emission control of a pyrene-thioindigo compound

Two distinct fluorescence modes of a thioindigo compound substituted with two pyrene groups on the 7 and 7′ positions were controlled by geometrical photoisomerization of the thioindigo skeleton.

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

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.