Electronic Structure Analysis of Iron(III)-Porphyrin Complexes by X-ray Absorption Spectra at the C, N and Fe K-Edges

Yamashige, Hisao; Matsuo, Shuji; Kurisaki, Tsutomu; Perera, R. C. C.; Wakita, Hisanobu

doi:10.2116/analsci.21.309

Cited by 22 publications

(27 citation statements)

References 36 publications

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“…Hence, N 1s XP spectra of free base porphyrin molecules, including 2H-P, 26,47 typically feature two peaks that are separated by approximately 2 eV. 48,49 This energy separation is reduced when the nitrogen atoms strongly interact with a substrate, such as the case with Cu(111), 22,50 while it is preserved on more weakly interacting surfaces 50 and in multilayers. 51 The nitrogen region is of special interest for following chemical reactions such as the metalation of free-base porphyrins [52][53][54] and is therefore frequently addressed.…”

Section: Resultsmentioning

confidence: 99%

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Diller

Klappenberger

Allegretti

et al. 2014

The Journal of Chemical Physics

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The templated growth of the basic porphyrin unit, free-base porphine (2H-P), is characterized by means of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy measurements and density functional theory (DFT). The DFT simulations allow the deconvolution of the complex XPS and NEXAFS signatures into contributions originating from five inequivalent carbon atoms, which can be grouped into C-N and C-C bonded species. Polarization-dependent NEXAFS measurements reveal an intriguing organizational behavior: On both Cu(111) and Ag(111), for coverages up to one monolayer, the molecules adsorb undeformed and parallel to the respective metal surface. Upon increasing the coverage, however, the orientation of the molecules in the thin films depends on the growth conditions. Multilayers deposited at low temperatures exhibit a similar average tilting angle (30° relative to the surface plane) on both substrates. Conversely, for multilayers grown at room temperature a markedly different scenario exists. On Cu(111) the film thickness is self-limited to a coverage of approximately two layers, while on Ag(111) multilayers can be grown easily and, in contrast to the bulk 2H-P crystal, the molecules are oriented perpendicular to the surface. This difference in molecular orientation results in a modified line-shape of the C 1s XPS signatures, which depends on the incident photon energy and is explained by comparison with depth-resolved DFT calculations. Simulations of ionization energies for differently stacked molecules show no indication for a packing-induced modification of the multilayer XP spectra, thus indicating that the comparison of single molecule calculations to multilayer data is justified.

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Section: Resultsmentioning

confidence: 99%

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Diller

Klappenberger

Allegretti

et al. 2014

The Journal of Chemical Physics

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“…[2][3][4][5] In the case of an indirect band gap material such as crystalline silicon, photosensitisation has the potential to substantially enhance the photoexcitation rate for electron-hole pairs, resulting in significant savings in material, and bringing about an exciting new paradigm for future solar cells and other optoelectronic devices. 6 Previous experimental studies have reported quenching of molecular fluorescence in proximity to silicon from evaporated dyes layers, 4,5,7 quantum dots, 8 Langmuir-Blodgett (LB) films [9][10][11][12] or zeolite structures 13 but at a greater distance of the emitter from the surface of silicon (>2nm) than the work presented in this paper where we focus on emitter-surface separations of less than 2 nm. The native oxide present on the surface of silicon then needs to be removed and the silicon surface subsequently functionalised.…”

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confidence: 93%

“…From the integrals for the pyrrolic (-NH-) at ~400.6 eV and iminic (=N) at ~398.7 eV nitrogen peaks confirms that the PpIX molecules were attached on the surface in accordance with previous XPS spectra on porphyrins in the literature. 2,6,7 It appears that some porphyrin groups have bound a metal atom. .…”

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confidence: 99%

Light harvesting in silicon(111) surfaces using covalently attached protoporphyrin IX dyes

et al. 2017

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We report the photosensitization of crystalline silicon via energy transfer using covalently attached protoporphyrin IX (PpIX) derivative molecules at different distances via changing the diol linker to the surface. The diol linker molecule chain length was varied from 2 carbon to 10 carbon lengths in order to change the distance of PpIX to the Si(111) surface between 6 Å and 18 Å. Fluorescence quenching as a function of the PpIX-Si surface distance showed a decrease in the fluorescence lifetime by almost two orders of magnitude at the closest separation. The experimental fluorescence lifetimes are explained theoretically by a classical Chance-Prock-Silbey model. At a separation below 2 nm, we observe for the first time, a Förster-like dipole-dipole energy transfer with a characteristic distance of R = 2.7 nm.

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“…Doping electron withdrawing ligands to metal center or neighboring carbon has been proved effective in weakening the adsorption energy. [4] Notably,o xygen containing species with high electron negativities are proved to be excellent energy level modifiers,where oxygen species such as -OH are bounded to the metal center to form new MN 4 OH. [5] However,t hese species are only autonomously introduced to date,w ith the controllable fixture being highly challenging.…”

Section: Introductionmentioning

confidence: 99%

Bridge Bonded Oxygen Ligands between Approximated FeN₄ Sites Confer Catalysts with High ORR Performance

et al. 2020

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The applications of the most promising Fe-N-C catalysts are prohibited by their limited intrinsic activities. Manipulating the Fe energy level through anchoring electronwithdrawing ligands is found effective in boosting the catalytic performance.However,such regulation remains elusive as the ligands are only uncontrollably introduced oweingt otheir energetically unstable nature.H erein, we report ar ational manipulation strategy for introducing axial bonded Otothe Fe sites,a ttained through hexa-coordinating Fe with oxygen functional groups in the precursor.M oreover,t he Om odifier is stabilized by forming the Fe À O À Fe bridge bond, with the approximation of two FeN 4 sites.The energy level modulation thus created confers the sites with an intrinsic activity that is over 10 times higher than that of the normal FeN 4 site.O ur finding opens an ovel strategy to manage coordination environments at an atomic level for high activity ORR catalysts.

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Electronic Structure Analysis of Iron(III)-Porphyrin Complexes by X-ray Absorption Spectra at the C, N and Fe K-Edges

Cited by 22 publications

References 36 publications

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Light harvesting in silicon(111) surfaces using covalently attached protoporphyrin IX dyes

Bridge Bonded Oxygen Ligands between Approximated FeN₄ Sites Confer Catalysts with High ORR Performance

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Electronic Structure Analysis of Iron(III)-Porphyrin Complexes by X-ray Absorption Spectra at the C, N and Fe K-Edges

Cited by 22 publications

References 36 publications

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Temperature-dependent templated growth of porphine thin films on the (111) facets of copper and silver

Light harvesting in silicon(111) surfaces using covalently attached protoporphyrin IX dyes

Bridge Bonded Oxygen Ligands between Approximated FeN4 Sites Confer Catalysts with High ORR Performance

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Bridge Bonded Oxygen Ligands between Approximated FeN₄ Sites Confer Catalysts with High ORR Performance