The core binding energies of some gaseous aromatic carboxylic acids and their relationship to profon affinities and gas phase acidities

Abstract

The C 1s and O 1s core binding energies of gaseous benzoic, phthalic, isophthalic, and terephthalic acids have been measured by X-ray photoelectron spectroscopy. The π-donor relaxation energies associated with the carbonyl oxygen ionization in these systems have been found to be around 2 eV, close to the value for acetic acid. Comparison of the O 1s binding energies in phenol and benzoic acid with the gas phase acidities shows that the increased acidity of benzoic acid is attributable mostly to initial-state inductive effects. A number of O 1s – proton affinity correlations have been used to predict proton affinities for these acids. It is found that benzoic acid is the strongest base and the weakest acid.

Positional and Conformational Isomerism in Hydroxybenzoic Acid: A Core-Level Study and Comparison with Phenol and Benzoic Acid

“…The calculated and fitted binding energies are summarized in Table , while the full list of the theoretical C 1s and O 1s ionization energies including explicit results for the lowest-energy conformers of salicylic acid, 3HBA, and 4HBA is presented in Tables S4–S7 of the SI. The present ionization energies agree well with the previously available data. , …”

“…The present ionization energies agree well with the previously available data. 10,7 The photoelectron spectra of the HBA isomers consist of three main features labeled A, B, and C due to the carboxyl carbon, the carbon bonded to the hydroxyl, and the other phenyl carbon atoms, respectively. This assignment is supported by the calculations, which are in good agreement with the measurements (Figure 2).…”

“…To the best of our knowledge, no comprehensive spectroscopic study of the above compounds was reported so far. Photoelectron measurements have been reported for the valence ionization of salicylic acid, three isomers of HBA, and benzoic acid, as well as the core-level photoelectron spectra of benzoic acid and phenol. − For phenol, the calculated core-level binding energies are also available …”

N-Doped Mesoporous Carbon Sheets/Hollow Carbon Spheres Composite for Supercapacitors

“…High-resolution XPS spectra for each element were obtained and fitted, and the corresponding forms of each element were analyzed. As shown in Figure b, the spectrum of C 1s of N-MCS/HCS-0.15 could be deconvoluted into three types of peaks, corresponding to C–C at 284.6 eV, C–N at 285.4 eV, and CO at 288.8 eV, which further indicates the existence of elements N and O in the surface of N-MCS/HCS. − The spectrum of O 1s (Figure c) could be deconvoluted into four types of peaks with binding energies of 530.0, 531.1, 532.9, and 536.4 eV from the contributions of oxygen in carboxyl groups, CO, and chemically adsorbed oxygen, respectively. ,, The high-resolution XPS spectrum of N 1s (Figure d) can be further deconvoluted into three peaks at 398.3, 400.9, and 403.8 eV corresponding to the contributions of pyridinic nitrogen (at 398.3 eV), quaternary nitrogen (at 400.9 eV), and pyridine N-oxide (at 403.8 eV) . Pyridinic nitrogen provides the active sites for electrode materials, and the quaternary nitrogen not only is the most stable nitrogen species during the process of pyrolysis but also can improve the electrical conductivity of the carbon materials. , …”

Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

“…6(a)), which is composed of two components of equal weight. The higher binding energy peak corresponds to photoemission from the hydroxyl oxygen of the carboxylic group and the lower binding energy component corresponds to photoemission from the carbonyl oxygen [19]. For a NDCA submonolayer structure on Ag(110) (Fig.…”