Abstract: 2-{2-Methyl-6-[2-(4-morpholin-4-yl-phenyl)-vinyl]-pyran-4-ylidene}-malononitrile(MDCM) and 2-{2,6-bis-[2-(4-morpholin-4-yl-phenyl)-vinyl]-pyran-4-ylidene}-malononitrile(BDCM) were synthesized from 2,6-dimethyl-4H-pyran-4-one, malononitrile, 4-(4-formylphenyl)morpholine and piperidine. 1H NMR and elemental analysis were used to characterize two compounds. The fluorescence spectra of the two compounds in solutions with different concentration were investigated. The solvent effects which impact on the fluorescence properties and the characteristics of the fluorescence in acidic solution were also systematically studied. The result show that fluorescence center wavelengthes of both compounds are in the red region, and the spectra exhibit red-shifts with increasing the polarity and acidity of the solvents. It is also found that the derivatives of MDCM and BDCM at concentrations of 1×10-4 mol/L and 1×10-5 mol/L, respectively, exhibit the highest fluorescent intensities. The solid fluorescent maximum wavelength of the BDCM has a 37 nm red-shift longer than that of MDCM, because the conjugate system of BDCM is longer than that of MDCM.

Key words: DCM, fluorescence, concentration quenching effect, solvent effect, pH influence