Barbituric acid, 1,3-dimethylbarbituric acid and 4-(diethylamino)benzaldehyde were purchased from Acros Organics (Geel, Belgium). 4-(Dimethylamino)benzaldehyde and DMSO was purchased from Sigma-Aldrich (Castle Hill, NSW, Australia). 4-(4-Morpholinyl)benzaldehyde, 4-(1-pyrrolidino)benzaldehyde and 4-(diethylamino)salicylaldehyde were purchased from Accela Chembio (Shanghai, China). Other solvents were purchased from Chem-supply (Adelaide, SA, Australia). All chemicals were used as received without further purification.
1H-NMR and 13C-NMR spectra were recorded by using a 400 MHz Bruker AV3HD-400 spectrometer (Billerica, MA, USA) at 298 K, with tetramethylsilane (TMS, δ = 0) as the internal standard. HRMS spectra were acquired by using a Thermo Scientific Q Exactive Plus Orbitrap LC–MS/MS instrument operating in ESI (Electrospray ionization) mode. UV-visible absorption spectra were recorded at room temperature on a Cary 300 UV-visible spectrophotometer (Agilent Technologies, Inc., Santa Clara, CA, USA) equipped with a 1.0 cm quartz cell. Fluorescence emission spectra were recorded on a Cary Eclipse Fluorescence Spectrophotometer (Agilent Technologies, Inc., Santa Clara, CA, USA) and used 1.0 cm quartz cells. Data were plotted by using Origin 2019.
1H-NMR and 13C-NMR spectra were recorded by using a 400 MHz Bruker AV3HD-400 spectrometer (Billerica, MA, USA) at 298 K, with tetramethylsilane (TMS, δ = 0) as the internal standard. HRMS spectra were acquired by using a Thermo Scientific Q Exactive Plus Orbitrap LC–MS/MS instrument operating in ESI (Electrospray ionization) mode. UV-visible absorption spectra were recorded at room temperature on a Cary 300 UV-visible spectrophotometer (Agilent Technologies, Inc., Santa Clara, CA, USA) equipped with a 1.0 cm quartz cell. Fluorescence emission spectra were recorded on a Cary Eclipse Fluorescence Spectrophotometer (Agilent Technologies, Inc., Santa Clara, CA, USA) and used 1.0 cm quartz cells. Data were plotted by using Origin 2019.