title: Exploration of ground and excited electronic states of aromatic and quinoid S,S-dioxide terthiophenes. Complementary systems for enhanced electronic organic materials.
abstract: We analyze the electronic and molecular structures for the ground and excited electronic states of aromatic terthiophene (3T), the quinodimethane 3',4'-dibutyl-5,5' '-bis(dicyanomethylene)-5,5' '-dihydro-2,2':5',2' '-terthiophene (3Q), and isologues with the middle ring S-oxidized (3TO2, 3QO2). These represent extremes of electron rich and deficient ground states, often exhibiting complementary properties. Oxidizing the central sulfur atom affects the molecular structure, electron affinity, and photophysical properties of both pi systems. The consequences for 3T include de-aromatization of the central thiophene, red-shifting of the electronic absorption spectrum, and lowering of the reduction potential. The electron deficient quinoid 3QO2 shows an enhancement of electron affinity from reducing the electron-donor ability of sulfur, and a blue-shifting of its electronic absorption spectrum was seen. Fluorescence emission is quenched in the sulfonated terthiophene, and the contrary effect again would be expected upon sulfonation of a quinoid emitter. Raman vibrational spectroscopy, electrochemistry, and UV-vis and fluorescence spectroscopies are analyzed in conjunction with theoretical calculations.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council of Canada, K1A 0R6, Ottawa, Canada.
authors.forename: Juan
authors.initials: J
authors.lastname: Casado
authors.forename: Marek Z
authors.initials: MZ
authors.lastname: Zgierski
authors.forename: Paul C
authors.initials: PC
authors.lastname: Ewbank
authors.forename: Michael W
authors.initials: MW
authors.lastname: Burand
authors.forename: Daron E
authors.initials: DE
authors.lastname: Janzen
authors.forename: Kent R
authors.initials: KR
authors.lastname: Mann
authors.forename: Ted M
authors.initials: TM
authors.lastname: Pappenfus
authors.forename: Anna
authors.initials: A
authors.lastname: Berlin
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Pérez-Inestrosa
authors.forename: Rocío Ponce
authors.initials: RP
authors.lastname: Ortiz
authors.forename: Juan T
authors.initials: JT
authors.lastname: López Navarrete