Investigations in the methoxy-iminocoumarin series: Highly efficient photoluminescent dyes and easy preparation of green-emitting crystalline microfibers

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• 作者：Nihel Abid-Jarraya ; Hamida Turki-Guermazi ; Kacem Khemakhem ; Souhir Abid ; Nathalie Saffon ; Suzanne Fery-Forgues
• 关键词：Iminocoumarin ; Methoxycoumarin ; Fluorescence ; Aggregation-induced emission (AIE) ; Crystallization-enhanced emission (CEE) ; Fluorescent fiber
• 刊名：Dyes and Pigments
• 出版年：February, 2014
• 年：2014
• 卷：101
• 期：Complete
• 页码：164-171
• 全文大小：1848 K

文摘

The fluorescence properties of four methoxy derivatives of 3-cyano-2-(N-ethoxycarbonyl)iminocoumarin, differing by the position and number of the methoxy substituents, were investigated. The 8-methoxy-iminocoumarin derivative was virtually non-fluorescent. The 7-methoxy-iminocoumarin derivative was only weakly fluorescent both in solution and in the solid state. The 6-methoxy-iminocoumarin derivative was poorly fluorescent in every solvent investigated, but it showed high photoluminescence in the solid state. To our knowledge, this is the first example of crystallization-enhanced emission (CEE) in the iminocoumarin series. The mechanism probably encompasses restricted rotation and favorable molecular packing. Moreover, this compound spontaneously crystallized as long microfibers. The 5,7-dimethoxy-iminocoumarin derivative exhibited good fluorescence in very polar solvents and was intensely luminescent in the crystalline state. The last two substitution patterns, 6-methoxy and 5,7-dimethoxy, could be of high interest for the design of new fluorescent materials.