SERRS spectra of azo dyes from deposited Ag colloid-azo dye films: investigating the mechanism of film formation

Michl, Martin; Vlčková, Blanka; Mojzeš, Peter

doi:10.1016/s0022-2860(98)00787-x

Cited by 4 publications

(17 citation statements)

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“…These modes are easily recognizable also in the conventional Raman pattern (Fig. , pattern ‘a’) and, together with other sharp features at 1143 and 1113 cm −1 , can be related to the neutral (azo) form of the dye . Another strong band at 1618 cm −1 , together with secondary modes at 1486, 1190, 1176, 908 527 and 474 cm −1 , can instead reasonably be attributed to the hydrazo (protonated) species of the molecule, confirming the existence of quinonoid character of the ring system in the protonated form …”

Section: Resultsmentioning

confidence: 56%

“…A more analytical examination reveals that the SER pattern of solid‐state methyl red (Fig. , pattern ‘b’) is basically dominated by the strong bands at 1364 and 1396 cm −1 ; the latter slightly down shifted (6 cm −1 ) with respect to that of the dye in solution . These modes are easily recognizable also in the conventional Raman pattern (Fig.…”

Section: Resultsmentioning

confidence: 88%

“…The possible contribution of spurious signals from the Ag colloidal paste is also reported. Small shifts of the SERS bands with respect to other Raman techniques (conventional and/or Resonance Raman) may also be related to weak Ag–dye interactions …”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 56%

Section: Resultsmentioning

confidence: 88%

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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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“…Though the spectra of MRH and MRHH are looking nearly the same, MRHH has rather strong azo-dye character than MRH. 10,11,12 This feature could be seen from the recovered strong bands at 1366 and 1397 cm −1 in Figure 2 range for MRHH may show ideas of any conformational changes (cis-to-trans, or vice versa) induced by adsorption of MR on the colloid surface, 13 or any structural changes (quinonoid-to-azo form, or vice versa) due to the inclusion of azonium group into cyclodextrin. 9 The spectra of MR species adsorbed on untreated silicaalumina are shown in Figure 3(a) and the band wavenumbers and tentative assignments are given in Table 4.…”

Section: Resultsmentioning

confidence: 95%

“…These spectra are very similar to the resonance Raman spectra reported previously using 457.9 nm or 514.5 nm excitation except Raman intensity features. 9,10,11 The spectrum of MR, Figure 2 …”

Section: Resultsmentioning

confidence: 99%

Fourier Transform Raman Studies of Methyl Red Adsorbed on γ-Alumina and Silica-Alumina

Park¹,

Lee²,

Min³

et al. 2004

Bulletin of the Korean Chemical Society

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Fourier transform Raman spectra of methyl red adsorbed on untreated and pretreated γ-alumina and silicaalumina calcined at 900 o C under 1 atm steam flowing were recorded. Spectral analysis shows that the active species adsorbed on γ-alumina was to be deprotonated methyl red, and on silica-alumina to be di-protonated. This indicates that γ-alumina adapted in this work holds Brönsted basicity, and silica-alumina Brönsted acidity. Raman intensities of methyl red on pretreated γ-alumina are about three times stronger than on untreated γ-alumina, while spectral features are unchanged. For silica-alumina, spectral features show modified vibrational characteristics upon surface hydroxylations generated from pretreatment. Consequently, the acidity loss for silica-alumina and the basicity gain for γ-alumina were observed by increasing the surface hydroxyl groups on the catalysts through pretreatment of the steam calcination.

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Multifunctional catalysts based on carbon nanotubes and titanate nanotubes for oxidation of organic compounds in biphasic systems

Santos

Jardim

Bicalho

et al. 2016

Journal of Colloid and Interface Science

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SERRS spectra of azo dyes from deposited Ag colloid-azo dye films: investigating the mechanism of film formation

Cited by 4 publications

References 4 publications

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

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

Fourier Transform Raman Studies of Methyl Red Adsorbed on γ-Alumina and Silica-Alumina

Multifunctional catalysts based on carbon nanotubes and titanate nanotubes for oxidation of organic compounds in biphasic systems

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