Raman and surface‐enhanced Raman spectroscopic studies of sulphanilic acid azochromotrope (SPADNS)

Abstract

The trisodium salt of 2-(4-sulphophenylazo)l,8-dihydroxynaphthalene-3,6disulphonic acid (SPADNS) was studied by Raman and surfaceenhanced Raman spectroscopy (SERS) techniques. The Raman spectra of SPADNS powder and aqueous solution were investigated and an assignment of the Raman bands was made taking into account its infrared absorption spectrum. SPADNS tautomers, o-bydroxyazo and oquinone hydrazone, are also discussed Although the assigameot is still preliminary owiog to the complex structure of the SPADNS molecule, it provides useful information for SERS investigations of SPADNS in aqueous silver sol and on silver film. "he results of SERS are compared with those of visible absorption spectra aod x-ray photoelectron spectra (XPS) aod the adsorp tioo configuration of the SPADNS molecule on a silver surface is considered.

Concentration and pH dependent SERS spectra of sulfanilic acid sodium salt on colloidal silver particles

“…The SO 3 symmetric stretching vibration27, 28 is seen at 1048 cm −1 for benzene sulfonate and at 1035 cm −1 for sulfanilic acid 11. For the title compound, the vibrations at 697, 492 (IR), 675 and 510 cm −1 (DFT) are assigned as the deformation bands of the SO 3 group 29. The band at 640 (IR), 644 (Raman) and 642 cm −1 (DFT) is assigned as the υCS stretching vibrational mode 30–32…”

“…[11] For the title compound, the vibrations at 697, 492 (IR), 675 and 510 cm −1 (DFT) are assigned as the deformation bands of the SO 3 group. [29] The band at 640 (IR), 644 (Raman) and 642 cm −1 (DFT) is assigned as the υC-S stretching vibrational mode. [30 -32] The out-of-plane γ CH bands are seen at 834 cm −1 in the IR spectrum and at 840 cm −1 in the Raman spectrum as expected for 1,4-disubstituted aromatic compounds.…”

Potential dependent SERS profile of sulfanilic acid on silver electrode

“…For benzenesulfonate, the SO 3 symmetric stretching vibration 20,21 is seen at 1048 cm 1 . The vibrations at around 686 and 560 cm 1 are assigned 22 to υSO 3 . The phenyl ring deformation bands are seen at 571, 500, 427 cm 1 in the IR spectrum and at 572 and 430 cm 1 in the Raman spectrum.…”

“…The phenyl ring deformation bands are seen at 571, 500, 427 cm 1 in the IR spectrum and at 572 and 430 cm 1 in the Raman spectrum. 22,23 The band at around 635 cm 1 is assigned as the C-S stretching vibrational mode. 10,24,25 CH bands are seen at 830 cm 1 in IR spectrum and at 821 and 803 cm 1 in the Raman spectrum as expected for 1-4 disubstituted aromatic compounds.…”

Near-Infrared Surface-Enhanced Raman Scattering of Ultrathin Films of CnAzoNaph(1,4)CmN+Br- (n = 7, 10, 12; m = 4, 6)

“…Band assignments for the spectra of C 10 AzoNaph(1,4)C 4 N + Br - in the various states are summarized in Table . These assignments were made by referring to Raman spectra of azobenzene and naphthyl derivatives, for which vibrational assignments have been well established. − Strong bands at 1412 and 1136 cm -1 in the spectra of Figure are assigned to −NN- and phenyl−N stretching vibrations, , respectively. The band position of 1445 cm -1 is close to that of the phenyl ring stretching vibration (ν 19 mode). , However, the intensity of the ν 19 band is generally weak in a Raman spectrum compared with that of the −NN− stretching band.…”