Study of charge-transfer interactions in polyvinylpyridine-halobenzoquinone complexes by x-ray photoelectron spectroscopy

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Abstract
The charge-transfer (CT) interactions in electroactive polymeric complexes formed by nonconjugated polymers: poly-2-vinylpyridine, poly-4-vinylpyridine, and various halobenzoquinone electron acceptors such as: o-chloranil, p-chloranil, o-bromanil, and p-fluoranil have been investigated by means of x-ray photoelectron spectroscopy (XPS). In spite of the relatively high degree of CT interactions, the conductivity of the complexes remains low and in the range of 10−11–10−6 S cm−1. XPS core-level spectra for halogens, nitrogen, and oxygen allow the steric hindrance to CT interactions in the various complexes to be investigated and compared. In all the complexes, the presence of a halogen anion, a positively charged pyridinium nitrogen, and an oxygen anion is observed. This is indicative that CT interactions may have resulted in adducts arising from the formation of linkages between the polymers and the acceptors.