Synthesis of isocoumarins and PAHs with electron-withdrawing substituents: Impact of the substituent nature on the photophysical behavior. (October 2022)

• Record Type: Journal Article
• Authors: Arsenov, Mikhail A.; Fedorov, Yury V.; Muratov, Dmitry V.; Nelyubina, Yulia V.; Loginov, Dmitry A.
• Is Part Of: Dyes and pigments. Volume 206(2022)
• Publication Date: 2022-10
• Subjects: Acenes -- C–H activation -- Fluorescence -- Isocoumarins -- Rhodium catalysis; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2022.110653
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: The efficient conditions for rhodium catalyzed oxidative coupling of electron-poor carboxylic acids with diphenylacetylene have been optimized. The best protocol uses Ag2 CO3 as an oxidant and DMF as a solvent. The reactions smoothly proceed with the formation of isocoumarins and polycyclic aromatic hydrocarbons (PAHs). The isonicotinic, coumalic, coumarin-3-carboxylic, 4-nitrobenzoic, 4-cyanobenzoic, 4-(ethoxycarbonyl)benzoic, and terephthalic acids were successfully involved in the annulation. In contrast, in the case of picolinic acid, the formation of the stable chelate complex Cp*RhCl(O, N-pic) prohibits the catalytic reaction. The photophysical properties of isocoumarins and PAHs in solutions, such as fluorescence emission and solvatochromic effects, have been studied. In particular, the isocoumarin dyes demonstrate a phenomenon of aggregation-induced emission, while PAHs with electron-withdrawing substituents exhibit strong fluorescence emission in the violet region (370–390 nm) with quantum yields up to 55%. Graphical abstract: Image 1 Highlights: A series of isocoumarins and PAHs with electron-withdrawing substituents was synthesized. The synthetic approach is based on the Rh-catalyzed CH activation in the presence of Ag2 CO3 as an oxidant. Isocoumarins exibit the phenomenon of aggregation-induced emission. Electron-withdrawing substituents increase the quantum yields of fluorescence emission of PAHs.