Synthesis, spectroscopic characteristic of novel fluorescent dyes of pyrazoline compounds.

Four novel fluorescence dyes of the pyrazoline were synthesized and fully characterized by means of (1)H, (13)C NMR, and HRMS. The optical, electrochemical properties were also investigated. Solvent effect on the fluorescence characteristics of the four compounds indicates that the emission wavelength was red-shifted with the increase of solvent polarity. As we expected, the results indicated that these compounds exhibited high quantum yields. Quantum chemical calculations were used to obtain optimized ground-state geometry, spatial distributions of the HOMO, LUMO levels of the compounds.