Surface‐enhanced Raman scattering study of the adsorption of the anthraquinone pigment alizarin on Ag nanoparticles

Scientific studies of works of art are usually limited by severe sampling restrictions. The identification of organic colorants, a class of compounds relevant for attribution and provenance studies, is further complicated by the low concentrations at which these compounds are used and by the interference of the protein-, gum-, or oil-binding media present in pigment and glaze samples. Surface-enhanced resonance Raman scattering (SERRS) was successfully used to identify natural organic colorants in archaeological objects, polychrome sculptures, and paintings from samples smaller than 25 m in diameter. The key factors in achieving the necessary sensitivity were a highly active stabilized silver colloid, obtained by the reproducible microwave-supported reduction of silver sulfate with glucose and sodium citrate, and a non-extractive hydrolysis sample treatment procedure that maximizes dye adsorption on the colloid. Among the examples presented are the earliest so far found occurrence of madder lake (in a 4,000 years old Egyptian object dating to the Middle Kingdom period), and the earliest known occurrence in Europe of the South Asian dyestuff lac (in the Morgan Madonna, a 12 th century polychrome sculpture from Auvergne, France).archaeology ͉ dyes

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“…2C. The correspondence with madder lake is evident [a detailed analysis of the SERS spectrum of alizarin was conducted by Cañamares et al (24)]. …”

Section: Resultsmentioning

confidence: 97%

Microanalysis of organic pigments and glazes in polychrome works of art by surface-enhanced resonance Raman scattering

Leona

2009

Proc. Natl. Acad. Sci. U.S.A.

174

103

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“…The best conditions for dye incorporation are at pH between 4 and 6, when the dye is in equilibrium between the Az and Az forms. 11,19 At pH 5, the intensity ratio was 10 times higher than at pH 3 or 11 for the same Az concentration (10 1 M). As can be seen in Fig.…”

Section: Raman Spectra Determination Of Alizarinmentioning

confidence: 90%

“…7(b)]. 11 These bands are sensitive to the molecular deprotonation and to the delocalization induced by the strong interaction with the metal.…”

Section: Raman Spectra Conformation Of Alizarin In Zr-ormosilmentioning

confidence: 99%

Spectroscopic identification of alizarin in a mixture of organic red dyes by incorporation in Zr‐Ormosil

Murcia‐Mascarós

Domingo

Sánchez-Cortés

et al. 2005

J Raman Spectroscopy

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Raman and UV-visible spectroscopy were applied to the study of a mixture of alizarin and carminic acid, two highly fluorescent anthraquinone dyes. The selective incorporation of alizarin into a Zr-Ormosil polymer induced intense Raman spectra that allow an easy, quick and unequivocal identification of this dye. Therefore, this method can be applied to the separation and identification of dyes, which is an important issue in the field of archaeometry. Raman spectroscopy was used to identify alizarin in Zr-Ormosil at different pH values, solvents and dye concentrations. The best conditions for composite formation were determined. Moreover, the Raman spectra allow us to propose an interaction model for the alizarin-Zr complexes where the monoanionic alizarin forms a chelate with Zr cations in the doped Ormosil similar to the alizarin-Al chelate formed in lacs and alizarin-Ag chelate formed in SERS experiments.

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“…In literature, several examples of sensors based on pH-sensitive dyes can be found. [24][25][26][27][28][29][30][31] A first step towards understanding the interaction of a dye molecule with a textile matrix can be made by studying the molecule solvated in water. We recently elucidated the pH-sensitive behaviour of the azo dye Ethyl Orange.…”

Section: Introductionmentioning

confidence: 99%

Substituent effects on absorption spectra of pH indicators: An experimental and computational study of sulfonphthaleine dyes

Meyer

Hemelsoet²,

Speybroeck³

et al. 2014

Dyes and Pigments

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Sulfonphthaleine dyes are an important class of pH indicators, finding applications in novel (textile) sensors. In this paper, we present a combined experimental and theoretical study to elucidate the halochromic behaviour of a large set of sulfonphthaleine compounds. Starting from an experimental analysis consisting of UV/Vis spectroscopy, the pH region and the absorption wavelengths related to the colour shift are obtained and pK a values are derived. The effect of the substituents on the pH region can be traced back to their electron donating/withdrawing properties. Time-Dependent Density Functional Theory (TD-DFT) is able to adequately produce the trend in experimental wavelengths. Proton affinities are used to assess the effect of substituents on the pH region. The combination of theory and experiment is able to give a better understanding of the pH sensitivity; the methodology in this work will be useful in future dye design and is applicable to other dye classes as well.

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Surface‐enhanced Raman scattering study of the adsorption of the anthraquinone pigment alizarin on Ag nanoparticles

Cited by 159 publications

References 12 publications

Microanalysis of organic pigments and glazes in polychrome works of art by surface-enhanced resonance Raman scattering

Microanalysis of organic pigments and glazes in polychrome works of art by surface-enhanced resonance Raman scattering

Spectroscopic identification of alizarin in a mixture of organic red dyes by incorporation in Zr‐Ormosil

Substituent effects on absorption spectra of pH indicators: An experimental and computational study of sulfonphthaleine dyes

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