Synthesis by Direct Arylation of Thiazole–Derivatives: Regioisomer Configurations–Optical Properties Relationship Investigation

The
synthesis of thiazole­(Tz)-based regioisomer materials using
selective direct arylation to avoid any protection steps has been
developed. A series of trimers in which the Tz groups sandwich either
an electron-rich or an electron-deficient unit, with a regioselective
orientation of the respective Tz unit, has therefore been synthesized.
This chemical strategy has also been followed to synthesize a second
series of pentamers in which the Tz group is used as a π-conjugated
bridge between an electron-rich central unit and electron-deficient
end-capping groups and vice versa. On both trimers and pentamers,
the effect of Tz orientation on the conjugation properties of the
synthesized materials was investigated by a combination of experimental
measurements and density functional theory calculations. This study
highlights that control of the orientation of the Tz unit leads to
the synthesis of the most conjugated regioisomer derivative. The present
work gives chemical synthesis tools for the synthesis of selectively
oriented Tz-based materials as well as a general guideline for the
design of Tz-based materials with the highest conjugation length,
including the Tz-orientation effect.