Structural, spectroscopic and computational study of 5‐(substituted phenylazo)‐3‐cyano‐1‐ethyl‐6‐hydroxy‐4‐methyl‐2‐pyridones

Abstract

Ten 5-(substituted phenylazo)-3-cyano-1-ethyl-6-hydroxy-4-methyl-2-pyridones were studied (five new compounds) to provide insight into the electronic effects of diverse substituents located at different positions in their phenyl moieties. The structural features of these dyes were examined by combining experimental and theoretical approaches. The crystal structures of two derivatives were revealed by X-ray crystallography and diverse packing modes owing to different intermolecular interactions (p-p stacking and lone pair-p interactions, as well as hydrogen bonds) were found. A study on lattice energy and energy related to the molecular pairs obtained from their crystal packing was performed. The tautomerism and ionisation of the dyes in ethanol or N,N -dimethylformamide solution were rationalised in terms of diazo component substitution pattern.

Novel azo pyridone dyes based on dihydropyrimidinone skeleton: Synthesis, DFT study and anticancer activity

“…The obtained absorption spectra suggest the existence of hydrazone tautomeric form in case of all investigated dyes[16][17][18]41,42].…”

“…However, the existence of hydrazone form is confirmed by NMR analysis in CF3COOD solution. The signal of low intensity at 15.03 ppm, in 1 H NMR spectrum, was ascribed to the N-H proton resonance of the hydrazone -NH group [41], and signal at 128.32 ppm, in 13 C NMR spectrum, was ascribed to C5=N.…”

Solvatochromism and quantum mechanical investigation of disazo pyridone dye

“…It can be observed that two absorptions of different intensity appear in the experimental UV–Vis spectrum in this solvent. According to the literature, the origin of this may be attributed to the acid–base equilibrium , that is, the presence of hydrazone and anionic forms (Scheme ). In order to determine the position of the UV–Vis maximum for the pure hydrazone tautomeric form in DMSO, hydrogen chloride is added dropwise to this solution, and the UV–Vis spectrum is presented in Figure , along with the experimental spectrum of DAPD in DMSO (before adding hydrogen chloride), and the scaled calculated spectra of the hydrazone and anionic forms.…”

New copper (II) complexes derived from azo pyridone dyes: Structure characterization, thermal properties, and molecular docking studies

“…The new TM complexes were synthesized in the reaction of azo pyridone dyes 1 and 2 with Cu(CH 3 COO) 2 ⋅H 2 O in DMF at room temperature (Scheme 1). Dyes ( 1 and 2 ), used as ligands in the synthesis, were fully characterized in our previous studies 36,37 . X‐ray crystallography analysis of the dyes confirmed the existence of the hydrazone form in the solid state (as depicted in Scheme 1).…”

“…Dyes 1 and 2 , used as ligands for the synthesis of the complexes, were previously synthesized and characterized 36,37 . Cu (CH 3 COO) 2 ⋅H 2 O (0.0093 g, 0.0467 mmol) was dissolved in 10 mL of DMF and added dropwise to the DMF solution (10 mL) of each dye (0.0934 mmol).…”