Related Experiment Video
Updated: Jul 14, 2026

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds
Published on: October 12, 2018
Spectroscopic investigation of conjugated polymers derived from nitroanilines
Rômulo A Ando1, Gustavo M do Nascimento, Richard Landers
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.
Related Concept Videos
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in the...
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Spectroscopy of Carboxylic Acid Derivatives
In the...
NMR Spectroscopy Of Amines
NMR Spectroscopy of Aromatic Compounds

