3-Phenothiazinyl propiolates – Fluorescent electrophores by Sonogashira coupling of ethyl propiolate. (August 2017)

• Record Type: Journal Article
• Authors: Götzinger, Alissa C.; Michaelis, Carina S.; Müller, Thomas J.J.
• Is Part Of: Dyes and pigments. Volume 143(2017)
• Page Start: 308
• Page End: 316
• Publication Date: 2017-08
• Subjects: Alkynoates -- Cross-coupling -- Cyclic voltammetry -- DFT calculations -- Fluorescence -- Phenothiazines -- Redox systems -- Solvatochromism; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2017.04.049
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Fluorescent ethyl 3-phenothiazinyl propiolates with reversible Nernstian oxidation potentials were efficiently synthesized by an improved Sonogashira coupling of aryl iodides and ethyl propiolate. The versatility of this modified alkynylation was illustrated by 13 ethyl 3-arylpropiolates in mostly excellent yields with a broad substrate scope. In addition to reversible one-electron oxidations, the title compounds reveal large Stokes shifts, high fluorescence quantum yields, and solvatochromic emission. The photophysical characteristics were corroborated and rationalized by DFT and TD-DFT calculations. Graphical abstract: Highlights: Ethyl aryl propiolates can be efficiently synthesized by an improved Sonogashira coupling with a broad substrate scope. Ethyl 3-phenothiazinyl propiolates, novel donor-acceptor conjugates with short dipole axes, are thereby easily accessible. The title compounds fluoresce with large Stokes shifts, high quantum yields and emission solvatochromicity. Ethyl 3-phenothiazinyl propiolates display fully Nernstian reversible oxidation potentials. (TD)DFT calculations rationalize the observed electronic characteristics and guide to novel functional p-electron systems.