A new MediaChrom (fluorosolvatochromic and acidochromic) based on bipolar donor-acceptor conjoined carbazolo-phenazine

[Display omitted] •Carbazolo-phenazine CP is a new conjoined bipolar MediaChrome.•CP exhibits fluorosolvatochromism as result of ICT in the excited state.•The dipole moment difference in the ground and excited states is 3.6 D.•Protonation of CP leads to violet coloration due to ICT in the ground state. MediaChromes are molecular systems characterized by a rigid aromatic backbone bearing electron-donating (D) and accepting (A) groups conjugated in the so-called push-pull D–π–A fashion. Electronic excitation of such systems results in increase of the dipole moment in the excited state due to intramolecular charge transfer (ICT), leading to remarkable excited-state properties. We have investigated fluorosolvatochromic and halochromic (acidochromic) behavior of carbazolo-phenazine (CP), a new bipolar molecular system characterized by conjoined donor carbazole and acceptor phenazine heterocycles. CP is shown to exhibit exceptional fluoromediachromic behavior due to ICT in the excited state; the difference in the dipole moments of ground- and singlet-excited states of CP is ca. 3.6 D units. ICT occurs also in the ground state upon protonation, which manifests in brilliant naked-eye visible violet coloration, namely, acidochromism.