(Coumarin-3-yl)-benzoates as a Series of New Fluorescent Compounds: Synthesis, Characterization and Fluorescence Properties in the Solid State

(Coumarin-3-yl)-benzoates, a series of coumarin derivatives were designed, synthesized and characterized as fluorescent compounds. The structural assignments of these compounds were examined based on their corresponding FT-IR, ESI-MS, and 1H- and 13C-NMR spectral data in addition to their crystal structures determined by X-ray diffractometry. The fluorescence spectra, recorded in the solid state, have been investigated. The effects of various substituents R on fluorescence properties were examined. As a result, compound 2c with an electron-donating substituent (R = t-Bu) exhibited the strongest fluorescence intensity whereas compound 2f with an electron-withdrawing group (R = CN) presented the weakest one.