Photophysical properties of 2,3-dihydroquinazolin-4(1H)-one derivatives
2,3-Dihydroquinazolin-4(1H)-one (DHQ) derivatives were synthesized by treatment of isatoic anhydride with amines and subsequent cyclocondensation with aldehydes or ketones. The derivatives were characterized by 1H and 13C NMR, elemental analysis and HRMS. Absorption and emission spectra of DHQ derivatives were recorded in different solvents (hexadecane, benzene, chloroform, methanol and acetonitrile). Both the absorption and the emission maxima are solvent-dependent and red-shifted. Molar extinction coefficients were determined to b 2364–4820 M−1 cm−1. The Stokes shifts of the compounds are large and increase with solvent polarity. This feature and the bathochromic effect shown for the absorption and emission processes indicate that the dipole moment of these fluorescent molecules is higher in the excited state than in the ground state. The fluorescence quantum yield and lifetime were obtained in different solvents for DHQ 4.