Platinum complex/Zn-porphyrin macrosystem assemblies: Electronic structure and conformational investigation by x-ray photoelectron spectroscopy

Abstract

In this study we used x-ray photoelectron spectroscopy (XPS) to characterize newly synthesized platinum/zinc-porphyrin assemblies. Our investigation provides information both on the electronic structure and on the composition and conformation of the linked systems. In particular, the N is and Pt 4f(7/2,5/2) spectra reveal the presence of a charge transfer interaction between the two subunits in which the charge flows from the Zn-porphyrin towards the platinum unit. Analysis of the: Cl 2p(3/2) core level electrons has led to a greater understanding of the conformational structure of these systems, verifying the occurrence of cis-trans isomerization from the pristine platinum complex to the linked assemblies, or the persistence of the conformation of the precursor platinum complex. We used XPS quantitative evaluation of the atomic ratios to estimate the subunit ratio between the Zn-porphyrinato and the Pt complex and also identified a platinum linked tetramer. The XPS results are consistent with nuclear magnetic resonance, infrared and matrix assisted laser desorption ionization spectroscopy

Ferrocene and Porphyrin Monolayers on Si(100) Surfaces: Preparation and Effect of Linker Length on Electron Transfer

“…This peak is assigned to the nitrogen atoms of the porphyrin (ZnEPMP) ring, which is in agreement with previously reported values. [50,51] After the 1,3-dipolar cycloaddition with ethynylferrocene, the Fe 2p 1/2 and Fe 2p 3/2 signals were clearly observed at 721.2 and 708.7 eV, respectively, for ferrocene monolayer 3 (Figure 3 d), consistent with values reported in the literature. [52][53][54] For porphyrin monolayer 4, Zn 2p 1/2 and Zn 2p 3/2 signals were respectively identified at 1045.5 and 1022.6 eV (Figure 3 e).…”

Characteristic differences in the X-ray photoelectron spectrum between B-DNA and M-DNA monolayers on gold

“…5e). A similar trend is observed for N 1s upon conversion of a free-base porphyrin to the corresponding metalloporphyrins [42,43]. For example, a typical free-base porphyrin has two peaks of roughly equal intensity at 399.2 and 397.2 eV corresponding to the non-conjugated and conjugated nitrogen respectively.…”

Visualizing the Product of a Formal Cycloaddition of 7,7,8,8‐Tetracyano‐p‐quinodimethane (TCNQ) to an Acetylene‐Appended Porphyrin by Scanning Tunneling Microscopy on Au(111)

“…The fact that the XP spectra can be interpreted without consideration of the surface molecular interaction provides a hint for the unmodified, low interaction between N and the Au substrate for the initial TCNQ (UPS data of TCNQ: see the Supporting Information) as well as for the adduct. As for porphyrin 1 (Figure 3 e), the N1s spectrum is dominated by the signal at 397.9 eV given by the four pyrrole nitrogen atoms within the porphyrin moiety, [22] while the DMA nitrogen signal is observed as a shoulder at approximately 399.05 eV. On the basis of the knowledge from aniline 3 and its adduct 4, the XP spectrum of the on-surface product between TCNQ and porphyrin 1 can now be deconvoluted into signals of the DMA nitrogen at 400.05 eV, the cyano nitrogens at 399.5 eV and 398.95 eV and the pyrrole nitrogens at 397.9 eV.…”