1,3,5-Triaryl-Δ2-pyrazolines with a nitro or amino group in the N-phenyl ring

A number of p-nitrophenylhydrazones of chalcones and 1-(p-nitrophenyl)- and 1-(p-aminophenyl)-3-aryl-5-phenyl-2-pyrazolines were synthesized, and their UV and IR spectra were measured. It is shown that the direction of polarization in the system of the ground and first excited states of the pyrazolines depends substantially on the character and position of the substituents introduced; the experimental data are compared with the results of calculation of the electronic states of the molecules by the Pariser-Parr-Pople (PPP) method. It was established that the nitro compounds have luminescence properties and that their absorption spectra in inert solvents have a vibrational structure.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1538–1543, November, 1977.