Electroreduction and spectrophotometric studies of some pyrazolyl-azo dyes derived from 3-acetylamino-1-phenyl-5-pyrazolone in buffered solutions (original) (raw)
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Synthesis, Characterization, Biological Activity and Electrochemical studies of Heterocyclic Azo Dye
A series of heterocyclic azo dyes were synthesized by diazotization of 2-Amino-5-(4-nitrophenyl)-1,3,4-thiadiazole by propionic acid and acetic acid in the ratio 2:3, followed by coupling with different coupling components. Synthesized heterocyclic azo dyes were characterized by UV-Vis, IR, 1H-NMR, 13C-NMR, element analysis and Mass spectral techniques. Electrochemical property of synthesized thiadiazole substituted azo dyes was studied by cyclic voltammetric technique. Synthesized azo dyes showed two reduction peaks indicating the two step reduction process. Probable mechanism for the reduction of azo dyes was proposed. The synthesized heterocyclic azo dyes were screened for biological activity. The results of these investigations revealed that the newly synthesized compounds are potent antimicrobial agents. Some of the synthesized compounds exhibit significant antimicrobial activity.
Synthesis and application of bifunctional reactive dyes pyrazolo[1,2‐a] pyrazole 3‐carboxylic acid
Pigment & Resin Technology, 2012
Purpose-The purpose of this paper is to synthesise, characterise and find out properties of some new bifunctional reactive azo dyes using pyrazolo[1,2-a]pyrazole 3-carboxylic acid fused systems as the chromophoric moiety, bearing good colour strength, lightfastness, and other favourable properties. Design/methodology/approach-The dyes are synthesised by diazotisation, coupling and cyclisation reactions. Firstly, synthesised 4-arylazo-1,5dioxopyrazolo[1,2-a]pyrazole 3-carboxylic acid chromophoric moieties and coupled with diazonium salts having the aforementioned reactive groups, thus yielding the new target reactive. The synthesised dyes were applied to cotton and wool fabrics under the typical exhaust dyeing conditions and their dyeing properties were investigated. The structures of these dyes are characterised and confirmed by melting point, elemental analysis, infrared, ultraviolet-visible spectroscopy (UV/VIS) and nuclear magnetic resonance (1H-NMR) data. Findings-The wavelength of maximum absorptions, molar extinction coefficients are strongly dependent on the electron donating ability of the substituents on the coupling moiety. The absorption bands of these dyes move towards longer wavelength as the polarity of the solvents and electron density of substituents on the coupling moiety increase. The dyes applied on cotton and wool showed higher exhaustion and fixation values, colour yields and fastness properties. Research limitations/implications-The method developed provided a simple producing fused pyrazolo[1,2-a]pyrazole disazo chromophoric systems based on 4-arylazo-1,5-dioxopyrazolo[1,2-a]pyrazole 3-carboxylic acid as well as reactive dyes applied on wool and cotton dyes. Originality/value-In this paper, three series of pyrazolo[1,2-a]pyrazole derivatives dyes are synthesised and characterised. They have not been registered in the literature previously.
The Electroreduction of Pyrazolone Glyoxalic Ester Derivatives (I) in Aqueous Buffered Media
Cheminform, 1991
The polarographic reduction of two series of pyrazolone derivatives in alcoholic buffered media indicated that these molecules predominate in the hydrazone form and are reduced via a 4 eirreversible process. The main electrolysis products, 3,6-bis(pyrazoline-5-on-3yl)piperazine-2,5-dione (3), and 3,6-bis(1-phenyl-pyrazoline-5-on-3yl)piperazine-2,5-dione (4) were isolated and identified. A mechanism has been suggested and discussed.
The electroreduction of pyrazolone glyoxalic ester derivatives in aqueous buffered media
Monatshefte f�r Chemie Chemical Monthly, 1990
The polarographic reduction of two series of pyrazolone derivatives in alcoholic buffered media indicated that these molecules predominate in the hydrazone form and are reduced via a 4 eirreversible process. The main electrolysis products, 3,6-bis(pyrazoline-5-on-3yl)piperazine-2,5-dione (3), and 3,6-bis(1-phenyl-pyrazoline-5-on-3yl)piperazine-2,5-dione (4) were isolated and identified. A mechanism has been suggested and discussed.
Journal of Photochemistry and Photobiology A-chemistry, 2005
Electrochemical and photochemical experiments in ethanol show that the tendency to the reduction of some azo dyes derived from 2aminobenzothiazole is parallel for both processes. This is attributed to the one-electron reduction of the dyes followed by a protonation of the resulting radical anions. The primary transient products of the reduction process, i.e. the radical anions, and their reactivity are characterized in solution at ambient temperature and under matrix conditions at 77 K by means of pulse radiolysis.
The use of some heterocyclic azo dyes in polarographic analysis of metal ions
Visnyk of the Lviv University. Series Chemistry, 2018
The method of linear sweep polarography was used to investigate the reduction of 4-(2-thiazolylazo)resorcinol (TAR) in the presence of Ga(III), Sc(III), In(III), Au(III), Co(II), Pd(II), Pt(IV), and Zr(IV) ions and the reduction of 4-(2-pyridylazo) resorcinol (PAR) in the presence of Au(III) and Pd(II) ions. The influence of pH, component concentration, sweep rate, on the reduction of azo dyes in the presence of metal ions was studied. Metrological and analytical characteristics of TAR-metal ions reduction were calculated. It has been established that Ga(III) and Sc(III) ions slightly affect (it was observed a potential shift in the cathodic region and a slight decrease of the reduction current) on the reduction of dye, and in the presence of Au(III), Pd(II), Zr(IV) ions the peak of the dye decreases at established pH range. In the presence of In(III), Pt(IV) ions the new cathode peaks are observed. It was found that the sensitivity of the determination is approximately the same for all investigated metals and LOQ is approximately 10-6 M.
A heterocyclic azo dye derived from 3H-pyrazol-3-one and m-cresol was synthesized and structurally confirmed by single crystal X-ray diffraction (SXRD) analysis along with UVeVis, FT-IR and NMR spec-troscopic techniques. This dye exists in azo tautomeric form which crystallizes in the orthorhombic Pbcn space group. However, in solution state, it predominantly exists in hydrazone tautomeric form as shown in the electronic absorption spectra. The influence of the acidic and basic media on the visible absorption spectra of that dye was also examined. The dyeing performance of the title compound on cotton yarn was appreciably good and show good fastness properties. The mutagenicity of the azo dye was screened by Ames salmonella/microsome assay. A considerable interaction observed with herring sperm-DNA, may be through a partial intercalation mode assessed by using electronic spectra. It also shows considerable biological activities such as antioxidant, anti-inflammatory and anti-arthritic activity with significant IC 50 value, make it a promising drug candidate.
The newly synthesized thirteen disperse disazo dyes 3a–3m were prepared by diazotization of 5-amino-4-arylazo-3-methyl-1H-pyrazoles 2a–2m and coupling with 2-methyl indole. Their structures were characterized by UV–vis, FT-IR, 1 H NMR and elemental analysis. Solvatochromic properties in different solvents were studied. Also, the effects of acid and base on the visible absorption spectra of the dyes were informed. Besides, the theoretical vibrational frequencies have been scaled and compared with the corresponding experimental data. 1 H NMR spectra were recorded and chemical shifts of the molecules were compared to TMS by using the Gauge-Independent Atomic Orbital (GIAO) method. A study on the electronic and optical properties, absorption wavelengths, excitation energy and dipole moment is performed using DFT method. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. All spectroscopic properties examined with the experimental techniques were supported with the computed results.
Electrochemical behaviour of dipyrone (metamizole) and others pyrazolones
Electrochimica Acta, 2018
The electrochemical oxidation of dipyrone (MTM) in aqueous medium was characterized using antipyrine (AA), 4-aminoantipyrine (4AA), 4-methylaminoantipyrine (MAA) and 4-dimethyl-aminoantipyrine (DMAA) as model molecules for the elucidation of all MTM voltammetric signals. The MTM and the other pyrazolones show up to four oxidation electrochemical processes. The voltammograms obtained in AA solutions presented an irreversible electrochemical oxidation process involving one electron at Eap3, which is common to all pyrazolone derivatives, while the amino pyrazolones present electrochemical oxidation processes at Eap0 or Eap1. The stabilization of the oxidation products depends on different effects: the proton release added to the thermodynamic stability, in the case of the imine formation at Eap0 (4AA and MAA) and the hyperconjugation (σstabilization) in the case of iminium formation (DMAA and MTM) at Eap1. The process observed at Epa0 corresponds to the pH-dependent oxidation of the primary and secondary enamines, while the process observed at Eap1 occurs in the tertiary enamines, is pH independent. The oxidation peak potential follows the order: MAA < 4AA < DMAA < MTM and it was demonstrated that DMAA in an aqueous medium can simulate the MTM in an aprotic medium; therefore, the analytical MTM determination can be performed using the DMAA aqueous analytical curve. DMAA and MTM analytical curves, presented a linear range from 10 µmol L-1 to 100 µmol L-1 with a LOD of 1.94 and 2.97 µM for DMAA and MTM, respectively, LOQ of 6.48 and 9.91 µM (n = 10) and, sensitivity of 0.96 µA/µM for DMAA and 0.92 µA/µM; with a recoveries of 95 to 105% for MTM.
Journal of Chemistry, 2013
The reactions of some metal ions of the third group (M(III)) with azo dyes were studied. Attention was focused on azo dyes with two hydroxy groups inortho-positions to azo group: eriochrome red B (ERB), eriochrome black T (EBT), eriochrome blue SE (EBSE), calcon (Calc), and kalces (KLC). The chelation is responsible for interaction of these dyes with Al(III), Sc(III), rare earth elements (REE) ions, Ga(III), and In(III). The complexes were studied using vis- and IR-spectrometry. One irreversible peak (P1) of complexes reduction was observed on voltammograms for all studied metal ions. The second peak P2 was observed only for Ga complexes with all investigated azo dyes. Based on the study, the possible mechanism of complexes reduction was proposed. Linear behavior has been found between the reduction peak currents of a set of metal complexes and the concentration of the respective metal cations. This can be used for metal ions determination by voltammetric methods.