On the tautomerism of 1-phenyl-3-substituted-pyrazol-5-ones and their photoinduced products — experimental and theoretical UV spectral analysis

Abstract

A detailed experimental and theoretical UV-spectral analysis of the tautomeric forms of 3-methyl-1-phenyl pyrazol-5-one and 1,3-diphenyl pyrazol-5-one as well as of the UV-irradiated photoinduced products of the latter compound were carried out. The experimental UV-spectra were compared with the theoretical ones obtained by CIS/6-31G**. Selected geometrical parameters of the different tautomers were estimated by ab initio calculations using the RHF/6-31G** level of theory and basis set, which have also been discussed with a view to the corresponding UV-results.

OH Radical Scavenging Activity of Edaravone: Mechanism and Kinetics

“…The nonionic form has its maximum absorption at 223 nm, in aqueous solution. This value is in good agreement with that reported by Chapkanov et al in ethanol (244 nm). The shape of the band is also similar, showing a subtle shoulder at the right of the maximum.…”

A ratiometric fluorescence chemosensor based on a coumarin–pyrazolone hybrid: the synthesis and an investigation of the photophysical, tautomeric and anion binding properties by spectroscopic techniques and DFT calculations

“…For this reason, determination of the tautomeric structures of pyrazolone derivatives has been studied extensively. [48][49][50][51][52] In this study, the tautomeric forms of C-2 were determined by spectroscopic techniques and from DFT calculations. The absorption and emission behaviours of C-2 were investigated in solvents of different polarity to confirm the expected tautomeric forms.…”