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 1H, 13C 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.

Graphical abstractFour novel fluorescence dyes of the pyrazoline were synthesized and the optical, electrochemical properties were also investigated. Quantum chemical calculations were used to obtain optimized ground-state geometry, spatial distributions of the HOMO, LUMO levels of the compounds.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New naphthalimide pyrazoline compounds containing carbazole were synthesized. ► UV–vis and fluorescence spectra of compounds were analyzed. ► HOMO/LUMO energy levels were obtained by CV and theoretical calculation. ► Incorporation of carbazole play an important role in enhancing HOMO energy levels.