Solid-State Fluorescence Properties and Crystal Structures of 7-(Diethylamino)coumarin Derivatives

7-(Diethylamino)-3-phenylcoumarin (1) gave strong emission band at 477 nm in the solid state when excited at 400 nm, but ethyl 2-[7-(diethylamino)-2-oxo-2H-1-benzopyran-3-yl]-4-thiazolecarboxylate (2) had no fluorescence in solid state.The crystal structures of 1 and 2 were analyzed by X-ray crystallography.The crystal of 1 had intermolecular C-H•••O, C-H•••N and C-H•••π interactions and that of 2 had intermolecular C-H•••O, π•••π, and S•••π interactions.Materials containing a coumarin (2H-1-benzopyran-2-one) component have been useful in many fields such as fluorescence materials and laser dyes, nonlinear optical materials, photorefractive materials, photo resists, intermediates for drug synthesis, luminescence materials, and analytical reagents etc. 1 Although the fluorescence of the coumarin itself is weak, the introduction of substituent group into coumarin increase the fluorescence intensity.Recently, we have reported the synthesis and fluorescence properties of 7-diethylaminocoumarin derivatives as fluoroionohores accessible for analytical purposes in the fields of analytical and biological chemistry. 2 The crystal structure analyses of 7-diethylaminocoumarin, 3 7-diethylamino-3-dimethylaminocoumarin, 4 methyl 4-(7-diethylamino-2oxo-2H-1-benzopyran-3-yl)benzoate, 5 and cholesteryl 4-(7-diethylamino-2oxo-2H-1-benzopyran-3-yl)benzoate 6 have been reported.