X-ray photoelectron spectroscopy of porphyrins

Abstract

The nitrogen Is binding energies of a series of porphyrins and several platinohematoporphyrin complexes obtained by x-ray photoelectron spectroscopy (XPS) are presented and discussed. The influence of different substituents at the periphery of the porphyrins has been studied; however, no significant change could be detected between the Njs binding energies of the porphyrins studied. A value of 2 eV has been found between aza and pyrrole type nitrogen binding energies. The nature of the sitting-atop (SAT) complex reported in the literature is discussed. XPS gives strong evidence for the existence of the SAT complex, cA-PtCl2H2(Hemato-IX). Two types of nitrogens located at 399.9 eV for N-H and at 398.6 eV for N-*Pt have been found in the SAT complex. Furthermore, the N]s region for the platinohematoporphyrin Pt(Hemato-IX) shows that the four nitrogens are equivalent. A value of 399.4 eV is found for the Njs binding energy of N-Pt where platinum is covalently bound to hematoporphyrin. The difference between the two types of nitrogen binding energies tends to zero in the series, H2(Hemato-IX) ( £ = 2.3 eV) -* ris-PtCl2H2(Hemato-IX) ( = 1.3 eV) -* Pt(Hemato-lX) ( £ = 0 eV), indicating a tendency toward equivalency upon platinum insertion.

Electrochemical and molecular simulation studies on the corrosion inhibition of 5,10,15,20-tetraphenylporphyrin adlayers on iron surface

“…The two close peaks were located at 398.8 and 400.0 eV, respectively. These fitted results were in good agreement with the literature [11]. The low binding energy corresponding to the aza type nitrogen and the high one is the pyrrole type nitrogen.…”

Electrolytic Conversion of Sacrificial Metal–Organic Framework Thin Films into an Electrocatalytically Active Monolithic Oxide Coating for the Oxygen‐Evolution Reaction

“…The corresponding spectra recorded for a Ni‐SURMOF@Au sample before and after electrolysis in KOH are shown in Figure for pristine Ni‐SURMOF@Au (top panel), the O1s spectrum allows to identify two different peaks assigned to carboxylate (531.7 eV) and a metal‐bound oxygen (533 eV) species . The detailed N1S spectrum of the SURMOF‐Ni@Au demonstrated three peaks ascribed to the Ni‐metalloporphyrin (399.8 eV), the azide groups (403.4 eV), and nitrate ions (407.2 eV) …”

Photocatalytic Hydrogen Evolution Based on Efficient Energy and Electron Transfers in Donor–Bridge–Acceptor Multibranched‐Porphyrin‐Functionalized Platinum Nanocomposites

“…On the other hand, as shown in Figure 4 b, for both nanospecies, the binding energy of the N 1s is located at about 399.6 eV 35. 36 Based on the XPS analysis, the Pt and N atoms in Pt‐TPPZ and Pt‐TPPX are calculated to be 10.53 to 1.05 mol % and 7.86 to 0.74 mol %, respectively. This means that the molar ratio of Pt to N of the nanocomposites is about 10:1, corresponding to an 80:1 molar ratio of Pt to the sensitizers.…”