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Updated: Jan 1, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Photophysical Properties of New Pyrazolone Based Azo- Compounds
1Art and Science Faculty, Department of Chemistry, Ordu University, 52200, Ordu, Turkey. e_bagdatli@yahoo.com.
Abstract:
New 5-pyrazolone based azo- dyes (2-5) and a bisazo- dye (6) were synthesized via diazo- coupling reaction with substituted aryl amines. All azo-5-pyrazolone compounds were characterized with the aid of FTIR, UV-Vis., 1H NMR, 13C NMR-APT and, GC-MS or ESI(+)-MS spectroscopic techniques. NMR studies showed that all azo- and bisazo- compounds, are in hydrazo-keto form except compound 5 which is in enol-azo form in solution. FTIR(ATR) studies indicated that compounds 2 and 4 are in azo-keto form, compounds 3 and 6 are in hydrazo-keto form and compound 5 is in enol-azo form in the solid state. All newly synthesized compounds were investigated for their absorption and emission characteristics. Photophysical properties of the solvent polarity effect and acid/base effect on the absorption and emission spectra were evaluated for an azo- (2) and a bisazo- compound (6). All azo-5-pyrazolone compounds showed fluorescence properties and the solvents with different polarities gave rise to shifts in the absorption and emission spectra of 2 and 6. The base addition did not affect the emission spectra while changing the absorption properties of the azo- and bisazo- compounds. Thermal work of 2 and 6 were carried out with TG/DTG technique and the results showed that compound 2 had adequate stability for industrial applications as a fluorescent material.
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