XPS Studies of Some Chemically Synthesized Polypyrrole–Organic Acceptor Complexes

Abstract

ABSTRACT:X-Ray photoelectron spectroscopy (XPS) studies have been performed on polypyrrole-2,3-dichloro-5,6-dicyano-p-benzoquinone (PPY-DDQ) and polypyrrole-tetrachloroo-benzoquinone (PPY---chloranil) complexes prepared via the simultaneous chemical polymerization and oxidation of pyrrole by the respective acceptor. XPS data suggested that the charge transfer interactions in both complexes probably proceeded further than the pure formation of a molecular complex. The negative charges of both organic anions were mainly localized on the oxygen and the chlorine atoms and to some extent on the nitrogen of DDQ. More extensive charge transfer interaction and higher fraction of pyrrole nitrogen with positive charge were observed in the PPY-DDQ complex, which exhibited a substantially higher electrical conductivity than the corresponding PPY ---chloranil complex.KEY WORDS XPS / Polypyrrole / 2,3-Dichloro-5,6-dicyano-p-benzoquinone / Chloranil / Charge Transfer Interactions / Due to their relative physicochemical and electrical stability and well-characterized stoichiometry, highly conductive polyheterocycles, polypyrrole (PPY) in particular, have attracted a great deal of interest in recent years. 1 · 2 Most of the recent interest on conductive PPYs, however, are devoted to the materials obtained from electrochemical polymerization and oxidation. For example, most of the X-Ray photoelectron spectroscopy (XPS) studies were centered on electrochemically prepared .PPYs and related polyheterocycles.3-7 We reported recently on the XPS technique as a convenient tool for analysing the polymer-acceptor interactions in chemically synthesized PPY-halogen complexes. 8

Study of polypyrrole aging by XPS, FTIR and conductivity measurements

“…8, the deconvolution of the N1s region is depicted. The signal at~400 eV was assigned to the eNH group of the pyrrole unit, the C]N defects of PPy are at~398 eV, and the polaron (CeN þ ) and bipolaron (C]N þ ) structures are at 401 eV and~402 eV, respectively [37,38]. Quantification of this deconvolution is summarized in Table 7.…”

ESCA Studies of Protonation in Polyaniline

“…Furthermore, comparison of the N 1 s peak B.E. between pyrrolylium nitrogen in polypyrrole (-NH-structure) 22 and that of the pyriPolymer J., Vol. 21, No.…”

Porphyrin‐Based Conducting Polymer Hydrogel for Supercapacitor Application

“…Similarly, the N 1s spectra of PPy, as shown in Figure d, also show two component peaks at 400.2 and 402.0 eV, corresponding to the neutral pyrrolic N and positively charged oxidized pyrrolic N, respectively . This oxidation level can be measured from the ratio of the area under the positively charged component peak N (401 eV) to that of the total area covered in the N 1s XPS spectrum . The N + /N ratio calculated for MnTSPP–PPy is 0.2, which is found to be greater than pristine PPy (0.1).…”

“…The peak corresponding to the positively charged nitrogen species with the binding energy of 401.0 eV reveals the oxidation level of PPy in MnTSPP–PPy . Similarly, the N 1s spectra of PPy, as shown in Figure d, also show two component peaks at 400.2 and 402.0 eV, corresponding to the neutral pyrrolic N and positively charged oxidized pyrrolic N, respectively . This oxidation level can be measured from the ratio of the area under the positively charged component peak N (401 eV) to that of the total area covered in the N 1s XPS spectrum .…”

“…In Figure c, the high‐resolution N 1s spectrum of MnTSPP–PPy has been deconvoluted into four major components which represent the pyrrolic N at a binding energy of 400.09 eV, oxidized pyrrolic N at 401.8 eV, the N bonded to Mn in Mn  N bond at 399.23 eV and N present in the porphyrin ring at the peak at 400.28 eV . The peak corresponding to the positively charged nitrogen species with the binding energy of 401.0 eV reveals the oxidation level of PPy in MnTSPP–PPy . Similarly, the N 1s spectra of PPy, as shown in Figure d, also show two component peaks at 400.2 and 402.0 eV, corresponding to the neutral pyrrolic N and positively charged oxidized pyrrolic N, respectively .…”