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 π 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.