Synthesis of some novel pyrazolo[5,1-c][1,2,4]triazine derivatives and investigation of their absorption spectra

In this study, 5-amino-4-hetarylazo-3-methyl-1H-pyrazoles were diazotised and coupled with malononitrile and ethyl cyanoacetate to give pyrazolylazo malononitriles and ethyl pyrazolylazo cyanoacetate, respectively. Ten novel pyrazolo[5,1-c][1,2,4]triazine dyes were synthesized by heating of pyrazolylazo malononitriles and ethyl pyrazolylazo cyanoacetate in glacial acetic acid. The dyes were characterized by elemental analysis and spectral methods. The solvatochromic behaviour of these diazo dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption maxima of the dyes are also reported. © 2006 Elsevier Ltd. All rights reserved

Synthesis and absorption spectra of some novel heterocyclic disazo dyes derived from pyridone and pyrazolone derivatives

Heterocyclic amines were diazotized and coupled with 3-aminocrotononitrile to give the 2-hetarylhydrazone-3-ketiminobutyronitrile (1a-1e) which can react with hydrazine hydrate and phenylhydrazine to afford the corresponding 5-amino-3-methyl-4-hetarylazo-1H-pyrazoles and 5-amino-3-methyl-4-hetarylazo-1-phenylpyrazoles (2a-2j), respectively. Then, some novel disazo dyes 3a-3j and 4a-4j were synthesized by diazotisation of 5-amino-3-methyl-4-hetarylazo-1H-pyrazoles and 5-amino-3-methyl-4-hetarylazo-1-phenylpyrazoles using nitrosyl sulphuric acid, coupling with 3-cyano-6-hydroxy-4-methyl-2-pyridone and 3-methyl-1H-pyrazole-5-one. The dyes were characterized by elemental analysis and spectral methods and the solvatochromic behaviour of the dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption maxima of the dyes were also reported. © 2006 Elsevier Ltd. All rights reserved

The synthesis and solvatochromic properties of some novel heterocyclic disazo dyes derived from barbituric acid

5-Amino-4-arylazo-3-methyl-1H-pyrazoles were diazotised and coupled with barbituric acid to provide 13 novel heterocyclic disazo barbituric acid dyes that were characterized by elemental analysis and spectral methods. The effects of varying the pH and solvent on the absorption of the dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position were examined in detail. © 2007 Elsevier Ltd. All rights reserved

Synthesis, solvatochromic properties and antimicrobial activities of some novel pyridone-based disperse disazo dyes

In this study, 5-amino-4-arylazo-3-methyl-1H-pyrazoles (2a-l) were diazotized and coupled with 3-cyano-6-hydroxy-4-methyl-2-pyridone to give pyridone-based disperse disazo dyes (3a-l). The newly synthesized twelve pyridone-based disperse disazo dyes were characterized by elemental analysis and spectral methods. The solvatochromic properties and antimicrobial activities of these disazo disperse dyes were also examined in detail. © 2013 Elsevier B.V

The synthesis, spectroscopic properties and theoretical calculation of some novel disperse disazo dyes derived from 3-amino-5-hydroxy-1-phenylpyrazole

In this study 5-amino-4-arylazo-3-methyl-1H-pyrazoles (1a-1m) were diazotised and coupled with 3-amino-5-hydroxy-1-phenylpyrazole to give disperse disazo dyes (2a-2m). The newly synthesized 13 disperse disazo dyes were characterized by elemental analysis and spectral methods. The solvatochromic behaviour of these disperse disazo dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption spectra of the disperse disazo dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position were also reported in detail. Additionally, theoretical calculations are performed for the disazo dyes. The molecular geometry and chemical shift are calculated by using ab initio calculations based on the density functional theory (DFT) in the ground state. The results obtained are in agreement with the experimental results. © 2009 Elsevier B.V. All rights reserved

Investigation of ground state tautomeric form of a heterocyclic disazo dye derived from barbituric acid by ab initio Hartree-Fock and density functional theory calculations

The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments of 10 tautomeric forms of a heterocyclic disazo dye [5-(3-methyl-4-phenylazo-1H-pyrazole-5-ylazo) barbituric acid] have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with 6-31G(d, p) basis set level. Calculations have shown that the most probably preferential form of the heterocyclic disazo barbituric acid dye in the ground state is azo-hydrazo-keto form corresponding to the experimental results. © 2008 Elsevier B.V. All rights reserved

Synthesis of some new pyrazolo[5,1-c][1,2,4]triazine derivatives and computational study

In this study, the synthesis novel of seven new pyrazolo [5,1-c][1,2,4]triazin derivative disperse dyestuffs was reported. First, 2-arylhydrazone-3-ketiminobutyronitriles were synthesized and reacted with hydrazine hydrate to afford 5-amino-4-arylazo-3-methyl-1H-pyrazoles. The 5-amino-4-arylazo-3-methyl-1H-pyrazoles were diazotised and coupled with ethyl benzoylacetate to give ethyl pyrazolylazo benzoylacetate. The final product was heated in glacial acetic acid and seven new pyrazolo [5,1-c][1,2,4]triazine dyestuffs were synthesized. FT-IR, 1H NMR and elemental analysis techniques were used to characterize synthesized dyestuffs. Density functional theory calculation methods were used for to determine the molecular geometries and spectroscopic properties of the new seven dyestuffs. The acquired results from calculations and experiments are conform each other. © 202

New coumarin-based disperse disazo dyes: Synthesis, spectroscopic properties and theoretical calculations

5-Amino-4-arylazo-3-methyl-1H-pyrazoles (3a-l) have been diazotised and coupled with 4-hydroxycoumarin to give rise to the coumarin-based disperse disazo dyes (3a-l). The newly synthesized twelve coumarin-based disperse disazo dyes have been characterized by using the elemental analysis and the spectral methods. The solvatochromic behavior of these dyes in various solvents is evaluated. Substituent, acid and base effects on the visible absorption spectra of the dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position are also reported in detail. Molecular geometries and spectroscopic properties of the compounds considered in this work are also analyzed by using ab initio calculation methods based on the density functional theory (DFT) in the ground state. The theoretical results obtained from DFT are compatible with the experimental results. © 2016 Elsevier B.V