2,4-Diaminoazobenzene hydrochloride dihydrate (chrysoidine S.L.)

Moreiras, D.; Solans, J.; Soláns, X.; Miravittles, C.; Germain, G.; Declercq, Jean‐Paul

doi:10.1107/s0567740881004135

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…These differences can be attributed to a resonance hybrid of the organic cation, as shown in Scheme 2. The same feature has been reported by Moreiras et al (1981)…”

Section: Crystal Datasupporting

confidence: 87%

Zigzag hydrogen-bonded sheets in the structure ofp-phenylazoaniline hydrochloride

Mahmoudkhani

Langer

2001

Acta Cryst E

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“…These differences can be attributed to a resonance hybrid of the organic cation, as shown in Scheme 2. The same feature has been reported by Moreiras et al (1981)…”

Section: Crystal Datasupporting

confidence: 87%

Zigzag hydrogen-bonded sheets in the structure ofp-phenylazoaniline hydrochloride

Mahmoudkhani

Langer

2001

Acta Cryst E

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“…Changes in the electronic structure upon protonation were described as being related to an increase in conjugation and π‐electron delocalization in the dye molecule . The structural features of the neutral form of methyl red, besides, provide no additional clue about this …”

Section: Resultsmentioning

confidence: 99%

FT‐Raman and surface‐enhanced Raman scattering (SERS) spectroscopic study of a methyl red@palygorskite hybrid nanocomposite: isomerization and protonation of the guest dye

Giustetto

Idone

Diana

2016

J Raman Spectroscopy

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An extremely stable hybrid composite, useable as a pigment in the Cultural Heritage and Materials Science fields, can be obtained by grinding and heating 2 wt% methyl red with palygorskite, a fibrous microporous clay mineral. Dye molecules are incorporated within the clay nanotunnels and/or superficial grooves, partly sheltered from the external environment and forming specific host–guest interactions that stabilize the composite. The molecular structure and surrounding interactions of the encapsulated methyl red molecules were studied by means of Fourier transform (FT) and surface‐enhanced Raman (SER) Spectroscopies – useful techniques to analyze adsorbates even at very low concentrations. Comparison between Fourier transform and SER spectra of the pristine dye and the hybrid composite shows that methyl red exists, after encapsulation in palygorskite, in its neutral (azo) and protonated (hydrazo) forms, both with planar morphology. Incorporation in the host framework favours significant transformation of the guest dye molecule from the azo to the hydrazo species, consistently with the composite synthesis being performed in acidic environment. The incidental addition of plasmonic substrates, used in SER spectra to enhance the Raman signal, further accentuates this conversion. Diffusion in the clay nanotunnels is expected to cause moderate ring deformations/distortions in the methyl red molecule, as reflected by the perturbation of selected Raman modes. The details about the specific orientations and interactions of the dye with the Ag colloid are discussed, as well as their effects on the Raman signal enhancement. Although a feasible quantification of their mutual amounts is impracticable, because of the too many variables involved, presence of several dye species in the host framework, each contributing to the nanocomposite colour, qualifies the studied complex as a polyfunctional organic/inorganic hybrid composite. Copyright © 2016 John Wiley & Sons, Ltd.

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“…Aniline yellow [4-(phenyldiazenyl)aniline, p-aminoazobenzene, PAZAN] is a diazo-dye precursor (O'Neil, 2001) and in the structures of its proton-transfer compounds with organic acids [oxalic acid (Mahmoudkhani & Langer, 2001b), phenylphosphonic acid (two concomitant polymorphs; Mahmoudkhani & Langer, 2002a), butane-1,4-bisphosphonic acid (Mahmoudkhani & Langer, 2002b), and the isomeric 3and 4-nitrophthalic and 5-nitroisophthalic acids (Smith et al, 2008)], as might intuitively be expected, the aniline functional group is protonated. However, in the purple-black hydrochloride (Yatsenko et al, 2000; and the hydrochloride of the analogous 4-phenyldiazenyl-1,3-diaminobenzene (Moreiras et al, 1981) the diazenyl group is protonated. Also, with phosphoric acid (Halasz et al, 2007), the orange monohydrogen phosphate is an anilinium salt while the purple dihydrogen phosphate salt is diazenyl-group protonated.…”

Section: Commentmentioning

confidence: 99%

Proton transferversusnontransfer in compounds of the diazo-dye precursor 4-(phenyldiazenyl)aniline (aniline yellow) with strong organic acids: the 5-sulfosalicylate and the dichroic benzenesulfonate salts, and the 1:2 adduct with 3,5-dinitrobenzoic acid

et al. 2009

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The structures of two 1:1 proton-transfer red-black dye compounds formed by reaction of aniline yellow [4-(phenyldiazenyl)aniline] with 5-sulfosalicylic acid and benzenesulfonic acid, and a 1:2 nontransfer adduct compound with 3,5-dinitrobenzoic acid have been determined at either 130 or 200 K. The compounds are 2-(4-aminophenyl)-1-phenylhydrazin-1-ium 3-carboxy-4-hydroxybenzenesulfonate methanol solvate, C12H12N3+.C7H5O6S-.CH3OH, (I), 2-(4-aminophenyl)-1-phenylhydrazin-1-ium 4-(phenyldiazenyl)anilinium bis(benzenesulfonate), 2C12H12N3+.2C6H5O3S-, (II), and 4-(phenyldiazenyl)aniline-3,5-dinitrobenzoic acid (1/2), C12H11N3.2C7H4N2O6, (III). In compound (I), the diazenyl rather than the aniline group of aniline yellow is protonated, and this group subsequently takes part in a primary hydrogen-bonding interaction with a sulfonate O-atom acceptor, producing overall a three-dimensional framework structure. A feature of the hydrogen bonding in (I) is a peripheral edge-on cation-anion association also involving aromatic C-H...O hydrogen bonds, giving a conjoint R(1)(2)(6)R(1)(2)(7)R(2)(1)(4) motif. In the dichroic crystals of (II), one of the two aniline yellow species in the asymmetric unit is diazenyl-group protonated, while in the other the aniline group is protonated. Both of these groups form hydrogen bonds with sulfonate O-atom acceptors and these, together with other associations, give a one-dimensional chain structure. In compound (III), rather than proton transfer, there is preferential formation of a classic R(2)(2)(8) cyclic head-to-head hydrogen-bonded carboxylic acid homodimer between the two 3,5-dinitrobenzoic acid molecules, which, in association with the aniline yellow molecule that is disordered across a crystallographic inversion centre, results in an overall two-dimensional ribbon structure. This work has shown the correlation between structure and observed colour in crystalline aniline yellow compounds, illustrated graphically in the dichroic benzenesulfonate compound.

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2,4-Diaminoazobenzene hydrochloride dihydrate (chrysoidine S.L.)

Cited by 6 publications

References 5 publications

Zigzag hydrogen-bonded sheets in the structure ofp-phenylazoaniline hydrochloride

Zigzag hydrogen-bonded sheets in the structure ofp-phenylazoaniline hydrochloride

FT‐Raman and surface‐enhanced Raman scattering (SERS) spectroscopic study of a methyl red@palygorskite hybrid nanocomposite: isomerization and protonation of the guest dye

Proton transferversusnontransfer in compounds of the diazo-dye precursor 4-(phenyldiazenyl)aniline (aniline yellow) with strong organic acids: the 5-sulfosalicylate and the dichroic benzenesulfonate salts, and the 1:2 adduct with 3,5-dinitrobenzoic acid

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