IR spectra and structure of polypyrrole

Abstract

Summary form only given. Infrared and Raman spectra of many polymers, including those with extended /spl pi/-electron conjugation have been successfully interpreted under the assumption of single, infinite, periodic chain model, adiabatic motion, and a harmonic potential. In addition, the force constants and electro-optical parameters (i.e., dipole moments of the chemical bonds, and their derivatives with respect to the natural coordinates) are assumed to be fairy local (i.e., independent of the structural details except for the location and the type of the few nearest neighbours), and hence can be transferred from small molecules of appropriate stereochemical structure. The frequencies and intensities of IR absorption bands are calculated, based on this model, for polypyrrole (PPy). Parameters are transferred from the pyrrole molecule. Theoretical vibrational spectra of polypyrrole are presented. Calculated spectra correspond well to experimental ones. There are no signs of electron delocalization in the IR spectrum of PPy. We analyzed spectra to discuss effects of possible nonplanarity of PPy.