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

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 10-pi-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. (C) 2017 Elsevier B.V. All rights reserved.