The syntheses, structures and azo–hydrazone tautomeric studies of three triazole/tetrazole azo dyes

Abstract

The azo–hydrazone tautomerism for three triazole/tetrazole azo dyes can be elucidated by 1H, 13C NMR and UV-vis spectra.

Synthesis, crystal structure and photophysical properties of chlorido[(E)-3-hydroxy-2-methyl-6-(quinolin-8-yldiazenyl)phenolato]copper(II) monohydrate

“…The N2-N3 bond distance of 1.293 (4) A ˚is typical for the N N double bond of an azo group. The structural features of the aromatic rings and the C11-O1 single-bond length of 1.300 (4) A ˚also indicate that the ligand adopts the azo structure, rather than the hydrazone structure, which is similar to the structures observed in analogous azo-metal complexes with other metals, including Ni, Cu, and Zn (Cai et al, 2016;Kochem et al, 2011Kochem et al, , 2014.…”

“…Azobenzene derivatives with hydroxy groups in the ortho or para position tend to form hydrazone tautomers (Jacques et al, 1979;Ball & Nicholls, 1982;Rauf et al, 2015). A hydrazone tautomer can be converted to an azo tautomer by complexation to the metal ion (Chen et al, 2012;Cai et al, 2016). In this study, we used the ortho and para isomer of the hydroxy-substituted azobenzene derivative, (E)-2-methyl-4-(quinolin-8-yldiazenyl)benzene-1,3-diol, to investigate azo-hydrazone tautomerism in its Cu II complex.…”

Synthesis and In Vitro Evaluation of Anti‐Leukemic Potency of Some Novel Azo‐Naphthol Dyes Conjugated with Metal Nanoparticles as Photosensitizers for Photodynamic Therapy

“…[30] The insignificant shifts in λ max are attributed to weak interactions (Van der Waals forces) between dyes and NMSs. [31] Thus, it's expected that derivatives (3 a, 3 b and 8) will show better PDT than other dyes after conjugation with MNPs.…”

“…[29] The two types of intramolecular hydrogen bonds are observed (OH…..N in azo and NH…..O in hydrazo tautomers) and both the position and the nature of the equilibrium depend on the solvent utilized and temperature. [30,31] The presence of the azo group (-N=N-) provides more extended electronic conjugation of πelectrons, and consequently allowing for a strong light absorption in the visible region of the electromagnetic spectrum. [32] The discovery and development of more potent and tumorspecific PSs conjugated with various types of NPs for use in PDT is of great importance and has been the focus of our research.…”

Strategies towards the control of one‐dimensional polypyrrole nanomorphology and conductivity

“…Template generation can be illustrated by the well‐known preparation of polypyrrole nanotubes supported by methyl orange, the method routinely reported in the literature . This dye is also currently used as an acidobasic indicator exploiting pH‐dependent azo–hydrazone tautomerism associated with intramolecular hydrogen atom transfer (Fig. ).…”