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Spectrochim Acta A Mol Biomol Spectrosc. 2008 Feb;69(2):319-26. Epub 2007 Apr 8.

Spectroscopic investigation of conjugated polymers derived from nitroanilines.

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  • 1Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077 São Paulo, SP, Brazil.

Abstract

For the first time, the resonance Raman spectroscopy was used to characterize polymers derived from meta- and para-nitroanilines. In order to improve the polymer structure analysis, other techniques were also used such as FTIR, UV-vis, XRD, XPS, EPR and N K-XANES. The insertion of strong electron-withdrawing groups (NO2) in polyaniline (PANI)-like backbone causes drastic changes in the lower energy charge transfer states, related to the polymer effective conjugation length. The resonance Raman data show that the NO2 moiety has a minor contribution on the CT state in poly(meta-nitroaniline), PMN, while in the poly(para-nitroaniline), PPN, the quinoid structure induced by para-substitution increases the charge density of NO2 groups, causing a more localized chromophore. The characterization of the imine nitrogen and of the protonated segments was done by XPS, N K-XANES and EPR spectroscopies and the lower polymerization degree of PPN, in comparison to PMN, is confirmed by XRD and TG data.

PMID:
17512243
[PubMed - indexed for MEDLINE]
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