A theoretical study of the low-lying excited states of thieno[3,4-b]pyrazine

Abstract

The low-lying electronic excited states of thieno͓3,4-b͔pyrazine have been studied using the multiconfigurational second-order perturbation CASPT2 theory with extended atomic natural orbital basis sets. The CASPT2 results allow for a full interpretation of the electronic absorption and emission spectra and provide valuable information for the rationalization of the experimental data. The nature, position, and intensity of the spectral bands have been analyzed in detail. A preliminary comparative study of the ground-state geometry of thieno͓3,4-b͔pyrazine has been performed at the coupled cluster single and doubles and density functional theory levels using a variety of correlation-consistent basis sets. Thieno͓3,4-b͔pyrazine exhibits a polyene-like structure in the ground state due to the bond localization in the pyrazine moiety. An aromatization of the pyrazine unit is predicted for the lowest-energy electronic excited states.

Thieno[3,4-b]pyrazines and their applications to low band gap organic materials

“…14 While that review contains a more in-depth discussion than possible to include in this current overview, there are a few critical properties to highlight here. Supported by calculations, 15,16 as well as electrochemical 11,17 and photophysical 15 studies, the TP HOMO is predominately thiophene-localized while the LUMO is of greater pyrazine contribution. As a result, TPs undergo a typical irreversible thiophene-based oxidation, but exhibit a Scheme 1 Conventional synthesis of thieno [3,4-b]pyrazines.…”

Thieno[3,4‐b]pyrazines and Its Extended Analogs: Important Buildings Blocks for Conjugated Materials

“…Although this new study was carried out at a higher computational level than the previous ZINDO calculations of Rasmussen and coworkers , the results obtained supported the earlier analysis of the optical spectra and the resulting assignments of the electronic transitions. The higher level calculations were able to provide a more detailed interpretation of the highest energy TP transitions .…”

Elaboration of low-band-gap π-conjugated systems based on thieno[3,4-b]pyrazines

“…Conversely, among the large diversity of chemical structures, thieno [3,4-b]pyrazines are well known to be suitable sub-structures to stabilize quinoid resonance moieties. Therefore, they appear to be good candidates to efficiently reduce the band gap [18,19].…”