Synthesis and fluorescence of crown ethers containing coumarin

The syntheses and fluorescence properties of a series of novel crown ethers containing coumarin group are presented. 2-(Benzocourmarin-3-acyloxymethyl) crown ethers were synthesized by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 2-hydroxymethyl crown ethers, while 4′-(benzocourmarin-3-carboxamido) benzo crown ethers were secured by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 4′-aminobenzo crown ethers. Only the ester-type crown ethers were fluorescent. As the polarity of the solvent increased, the emission maximum λem showed a slight red shift. DMSO was used as the fluorescence quenching solvent. Increased fluorescence was observed upon the addition of alkali and alkaline earth metal ions.