The optical properties, synthesis and characterization of novel 5-aryl-3-benzimidazolyl-1-phenyl-pyrazoline derivatives

A series of novel 5-aryl-3-benzimidazolyl-1-phenyl-pyrazoline derivatives were synthesized by the reaction of benzimidazolyl chalcone and phenylhydrazine in 41–72% yields. The compounds were characterized using IR, 1H NMR and HRMS. Absorption and fluorescence spectra were measured in different organic solvent. An intense absorption maxima was noted at ca. 370 nm and emission maxima was noted at ca. 460 nm. The absorption spectra of the pyrazoline derivatives reveal that 5-aryl group attached to the pyrazoline ring hardly influenced the maximum absorption. The fluorescence spectra of these compounds indicated the emission wavelength was red shifted and the fluorescence intensity was decreased with the increase in solvent polarity.

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► Novel pyrazoline derivatives were prepared and fully characterized.
► UV–vis absorption and fluorescence spectroscopy of all compounds were measured.
► Influence of solvent on UV–vis absorption and fluorescence spectroscopy was examined.