Pyrrolopyrazine-based triads decorated with donor-acceptor groups: pH and polarity induced visible color switching sensors

Three series of pyrrolopyrazine-based triads functionalised with strong donor-acceptor groups were obtained by twofold Suzuki cross-coupling reactions under microwave irradiation. The resulting push-pull chromophores were intensively colored. Their properties can be tuned by proper chemical engineering. The photophysical, thermal, and electrochemical properties were thoroughly investigated. The coupled computational and classic synthetic strategies show that subtle changes in the terminal group, modulates the optical and electrochemical properties, resulting in broad absorption and emission spectra. The prepared compounds revealed large Stokes shift, acidochromism, positive solvatochromism and color tunability in various solvents. [Display omitted] •A series of molecules with pyrrolopyrazine core decorated with D-A groups are prepared.•The photophysical and thermal properties of the compounds are described.•Theoretical studies confirm the ICT characteristics of the molecules.•These chromophores act as polarity sensors and are suitable for pH sensing applications.