Isomerically pure anthra[2,3-b:6,7-b']-difuran (anti-ADF), -dithiophene (anti-ADT), and -diselenophene (anti-ADS): Selective synthesis, electronic structures, and application to organic field-effect transistors

A new straightforward synthesis of isomerically pure anthra[2,3-b:6,7-b'] -difuran (anti-ADF), -dithiophene (anti-ADT), and -diselenophene (anti-ADS) from readily available 2,6- dimethoxyanthracene is described. The present successful synthesis makes it possible to overview the linear-shaped anti- acenedichalcogenophene compounds, that is, benzo[1,2-b:4,5-b']-, naphtho[2,3- b:6,7-b']-, and anthra[2,3-b:6,7-b']- difuran, -dithiophene, and -diselenophene. By comparing their electrochemical and photochemical properties, the electronic structures of acenedichalcogenophenes can be expressed as the outcome of balance between the central acene core and the outermost chalcogenophene rings. Among isomerically pure parent anti-anthradichalcogenophenes, anti-ADT and anti-ADS can afford crystalline thin films by vapor deposition, which acted as active layer in organic field-effect transistors with mobility as high as 0.3 cm ² V ^-1 s ^-1 for ADT and 0.7 cm ² V ^-1 s ^-1 for ADS. The mobility of isomerically pure anti-ADT is higher by several times than those reported for isomercally mixed ADT, implying that the isomeric purity could be beneficial for realizing the better FET mobility. We also tested the diphenyl derivatives of anti-ADF, -ADT, and -ADS as the active material for OFET devices, which showed high mobility of up to 1.3 cm ² V ^-1 s ^-1.