Raman and surface-enhanced Raman study of asymmetrically substituted viologens

Journal Article · Thu Dec 01 00:00:00 EST 1988 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100335a028· OSTI ID:6188901

Lu, T; Cotton, T M; Hurst, J K; Thompson, D H.P.

The normal Raman (NR), resonance Raman (RR), surface-enhanced Raman scattering (SERS), and surface-enhanced resonance Raman scattering (SERRS) spectra of the three redox forms of several asymmetric viologens, N-octyl-N'-methylviologen (C/sub 8/MV), N-dodecyl-N'-methylviologen (C/sub 12/MV), and N-hexadecyl-N'-methylviologen (C/sub 16/MV), have been characterized and compared with the corresponding spectra of the three redox forms of methylviologen (MV). It was observed that the substituents of the two N atoms of the viologen do not affect its overall symmetry. Only the Raman bands near 1200 cm/sup /minus/1/, containing major contributions from the N-alkyl stretching vibrations, are affected by the asymmetric substitution. The RR spectra of both the monomer and dimer forms of the cation radicals were obtained by varying the experimental conditions used in their preparation. As previously observed for MV, dimerization of the asymmetric viologen radicals produces splitting of certain RR bands. Resonance Raman spectra of the fully reduced viologens were also obtained and used to monitor the disproportionation reaction between the dication and fully reduced form of the viologen. Surface-enhanced Raman and SERRS spectra of the different asymmetric viologens were found to vary slightly due to changes in their adsorption behavior with increasing chain length of the alkyl substituent.

• Research Organization: Univ. of Nebraska, Lincoln (USA)
• DOE Contract Number: FG02-84ER13261; AC06-83ER13111
• OSTI ID: 6188901
• Journal Information: J. Phys. Chem.; (United States), Vol. 92:24
• Country of Publication: United States
• Language: English

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37 INORGANIC
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PHYSICAL AND ANALYTICAL CHEMISTRY
BIPYRIDINES
STRUCTURAL CHEMICAL ANALYSIS
DIMERS
ELECTRON TRANSFER
EXPERIMENTAL DATA
MOLECULAR STRUCTURE
MONOMERS
RAMAN SPECTROSCOPY
REDOX REACTIONS
RESONANCE SCATTERING
VIBRATIONAL STATES
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CHEMICAL REACTIONS
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ENERGY LEVELS
EXCITED STATES
HETEROCYCLIC COMPOUNDS
INELASTIC SCATTERING
INFORMATION
LASER SPECTROSCOPY
NUMERICAL DATA
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ORGANIC NITROGEN COMPOUNDS
PYRIDINES
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400201* - Chemical & Physicochemical Properties
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