title: Synthesis, electronic, and electro-optical properties of emissive solvatochromic phenothiazinyl merocyanine dyes.
abstract: Phenothiazinyl merocyanine dyes with variable substitution patterns on the peripheral benzene ring were synthesized in good yields by Knoevenagel condensation of the corresponding phenothiazinyl aldehydes and N-methylrhodanine or indan-1,3-dione. The electronic properties were investigated by cyclic voltammetry, absorption, electro-optical absorption, and emission spectroscopy. All these merocyanines reveal reversible redox behavior that stems from the phenothiazinyl-centered oxidation to give stable radical cations. The redox potentials strongly correlate with Hammett σ(p) parameters. All merocyanines reveal large Stokes shifts. They also display a pronounced emissive solvatochromism, which is caused by large dipole moment changes upon excitation from the ground to the excited state. These findings are supported by solvatochromism studies and time-dependent DFT computations.
authors.affiliation: Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Hauck
authors.forename: Matthias
authors.initials: M
authors.lastname: Stolte
authors.forename: Jan
authors.initials: J
authors.lastname: Schönhaber
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Kuball
authors.forename: Thomas J J
authors.initials: TJ
authors.lastname: Müller