Synthesis, characterization, and dc conductivity of hydrogen-bonding dibenzotetrathiafulvalene (DBTTF) based salts

The synthesis, characterization, and dc conductivity of organic conductors, 1-[2-(1,3-benzodithiol-2-ylidene)-1,3-benzodithiol-5-yl]ethylammonium tetrafluoroborate ([DBTTFCH(Me)NH3+]BF4−) and 1-[2-(1,3-benzodithiol-2-ylidene)-1,3-benzodithiol-5-yl]ethylammonium bromide ([DBTTFCH(Me)NH3+]Br−) salts are presented. These salts are prepared by mixing the corresponding primary amine and Brønsted acid in a one-to-one ratio without electrochemical oxidation. The change in the electronic state of insulating DBTTFCH(Me)NH2 into conductive [DBTTFCH(Me)NH3+]X− (X = BF4 and Br) salts and the carrier generation upon salt formation were confirmed by diffuse reflectance (UV–vis) and ESR spectra. The concentration of localized radicals is estimated to be 1 radical/3.3 units and 1 radical/1.8 units for BF4 and Br salts, respectively. The possible carrier generation mechanism is proposed by 1H NMR and ESI-TOF-MS spectroscopic analyses. The dc conductivity and the activation energy are σrt = 2.3 × 10−3 S/cm with 0.24 eV for the BF4 salt, and σrt = 1.3 × 10−3 S/cm with 0.21 eV for the Br salt.