Crystal structure, spectra properties and comparative studies on a 2-pyrazoline derivative

A 2-pyrazoline derivation of 1-phenyl-3-(4-methylphenyl)-5-(3,4-dimethyl phenyl)-2-pyrazoline has been characterized by X-ray single crystal diffraction, UV-vis and fluorescence spectroscopy. For the title compound, density functional theory (DFT) calculations of the structure and natural population atomic charge analysis have been performed at B3LYP/6-311G** level of theory. By using TD-DFT method, electron spectra of the title compound have been predicted, which suggest the B3LYP/6-311G** method can approximately simulate the electron spectra for the system presented here. Comparative studies on the title compound with 1-phenyl-3-(4-methylphenyl)-5-phenyl-2-pyrazoline indicate that introducing electron-donating groups in 5-phenyl ring of pyrazoline ring influences the peak location and intensity in electronic and fluorescence spectra.

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► Crystal structure and spectra properties of a 2-pyrazoline were obtained.
► DFT calculations of structure, NPA analysis and electronic spectra were performed.
► Two methyl groups in 1 change the atomic charge distribution.
► Two methyl groups make the electron transition in 1 more easier than in 2.
► Two methyl groups in 1 increase the fluorescence emission intensity.