Varying temperature FT-IR and a.c. conductivity analyses of high-capacitance fast ion conducting HCl salt of hexaamidocyclotriphosphazatriene

Sayed, Moein B.

doi:10.1016/s0167-2738(99)00300-8

Cited by 6 publications

(1 citation statement)

References 15 publications

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“…The aim of this work is to pursue spectral−structural correlation analysis for symmetric azo phenol derivatives of melamine of relevant structures to other recently published azo phenol derivatives of cyclotriphosphazene − in more detail. The developed derivatives could also be of further interest to scientists working on coordination and supramolecular chemistry.…”

Section: Introductionmentioning

confidence: 99%

H-NMR, UV−Visible, and FT-IR Spectral Analyses for the Conflicting Impacts of Proton Mobility and H-Bonding Association on the Mesomeric Structure in Azopyrogallol, Catechol, Resorcinol, Quinol, and Phenol Derivatives of Melamine

Sayed

2004

Ind. Eng. Chem. Res.

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Symmetric coupling of a hardly forming multifunctional diazonium salt of low basicity melamine with phenols is performed with difficulty with a very slight decline in the higher phenol acidity. The azopyrogallol derivative maintains the melamine D 3h symmetry explicit in the 1 H-NMR spectrum showing the azo substituents in the same magnetic environment with the phenyl ring protons shown in a sharp (6.30 ppm) resonance and the phenolic protons in a broad (8.70 ppm) signal. This weakly deshielded simple spectrum of singlet signals is assigned to a quinonoid structure, particularly when the broad signal characteristic of phenolic proton exchange is considered. The broad signal sharpens and shifts downfield indicating a progressing association for the other azophenol derivatives. The quinonoid π-π* transition wavelength also falls with the association. The quinonoid structure seems to decline with association in favor of a more mesomeric benzenoid structure that stabilizes the π-orbital versus the π*-orbital into a shorter wavelength π-π* transition. Variable temperature FT-IR spectroscopy compares the effects of proton mobility and H-bonding association on the mesomeric structure of these azo derivatives in the more dense solid state. Consistent with the quinonoid structure, azopyrogallol shows high C-N and C-O but low N-N and O-H bond order that invariably changes with proton mobility and H-bonding association. At variance with azopyrogallol inclining to the quinonoid structure of high proton mobility, azoquinol lacks such a property so that it leans to the benzenoid structure where rotation around the NdN bond is difficult that allows for a possible distortion in the dense solid state. The other azo derivatives arrange with a structure shifting with variation in the proton mobility: azopyrogallol ∼ azocatechol ∼ azophenol ∼ azoresorcinol ∼ azoquinol with quinonoid [hydrazo] form and proton mobility at the azopyrogallol end and benzenoid [azo] form and H-bonding association at the azoquinol end.

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