The photoelectron spectra of tetraphenylporphine and some metallotetraphenylporphyrins

Khandelwal, Suresh; Roebber, J. L.

doi:10.1016/0009-2614(75)85292-4

Cited by 91 publications

(66 citation statements)

References 10 publications

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“…As expected, the deeper lying orbitals (namely those contributing to Peaks 9 and 10) show a higher -character (higher inter-atomic orbital density). For the rest of the spectrum a very close similarity is found with previous data on TPP thin films [20] and gas phases experiments [18,41,42]. Specifically, Peak 5 has a strong contribution from the four phenyl groups (but not the amino groups) although in the case of TAPP an important spectral weight to Peak 5 is also found to come from the macrocycle.…”

Section: Resultssupporting

confidence: 74%

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Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Giovanelli

Lee

Lacaze‐Dufaure

et al. 2017

Journal of Electron Spectroscopy and Related Phenomena

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. b s t r a c tThe valence and conduction bands of a thin film of tetra(4-aminophenyl)porphyrin (TAPP) are investigated by direct and inverse photoemission as well as by comparison to density functional theory (DFT) calculations. By projecting the electronic eigenfunctions onto the molecular framework it was possible to interpret the origin of each spectroscopic feature. Although the majority of the photoemission spectrum is attributed to the unsubstituted tetraphenylporphyrin (TPP) parent molecule, several features are clearly due to the amino substitution. Substitution also has important consequences for the energy positions of the frontier orbitals and therefore on the low-energy electronic excitations. The measured electronic transport energy gap (E g = 1.85 eV) between the highest occupied molecular orbital (HOMO) and lowest unoccupied (LUMO) in TAPP is found to be significantly reduced with respect to TPP. Moreover, an increased energy separation between the two highest occupied states (HOMO and HOMO−1) is found both experimentally and by DFT calculations. Such evidence is attributed to an increased HOMO orbital destabilization due to an enhanced electron-donor character of the phenyl substituents upon amino functionalization. Finally, the above findings together with further time-dependent DFT calculations are used to interpret the effect of the amino groups on the UV-Vis absorption spectrum, namely an overall red-shift of the spectrum and remarkable intensity changes within the Q band.

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Section: Resultssupporting

confidence: 74%

“…In fact, several studies have proven that the spectral features measured on thin films 1 are equivalent to those measured on better resolved gas phase spectra [18,20,[40][41][42] and can then be compared to calculated density of states (DOS). In Fig.…”

Section: Resultsmentioning

confidence: 99%

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Giovanelli

Lee

Lacaze‐Dufaure

et al. 2017

Journal of Electron Spectroscopy and Related Phenomena

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“…(iii) Photoelectron spectroscopy of the occupied and unoccupied states show distinct and easily discernible peaks generally matching published UPS data and theoretical expectations. 63,[82][83][84] For low and moderate 2H-TPP coverages on Ag, distinctive molecular orbital features of the occupied states are absent and peak splitting of the LUMO is observed for 2H-TPP/Au(111) by inverse photoemission. (iv) DFT calculations show that the binding energy for 2H-TPP on Ag in various positions and geometries is largest for a bridging position at step edges, with rotated "X" geometry, whereas the binding energy of the nitrile components of the macrocycle is larger by more than a factor of 2 on Cu(111) and independent of the adsorption site.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Self-Assembly and Properties of Nonmetalated Tetraphenyl-Porphyrin on Metal Substrates

et al. 2010

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IntroductionThe self-assembly of porphyrins on well-defined surfaces is attracting considerable interest because it promises to create surface patterns with nanometer dimension that exhibit specific electronic, sensoric, optic, or catalytic functionality 1-3 or even interesting magnetic properties. 4,5 The ability of porphyrin to show self-organization and to accommodate metal atoms in their macrocycle is exploited, for instance, to form metal−organic frameworks or adsorbed layers for catalysis. [6][7][8][9] The selfassembly is mainly driven by noncovalent metal−organic coordination interactions, which is well-known and important in solution-based 3D supramolecular chemistry. [10][11][12][13][14][15] Porphyrin molecules have been adsorbed onto surfaces to form supramolecular networks from solution, [16][17][18][19] electrochemically 20,21 or by thermal evaporation under vacuum conditions. [22][23][24][25][26][27][28] While there is a rich literature on the electronic structure of these adsorbates, the surface adlayer structures have also been characterized with scanning force microscopy, scanning tunneling microscopy, or X-ray absorption near-edge structure analysis. 29 The rationale of such experiments on 2D structures has been to study the long-range interactions that determine the self-assembly processes. It has been demonstrated that the bottom-up fabrication of highly organized porphyrin layers, as well as of porphyrin-based multicomponent molecular entities, depends on the interplay of molecule−molecule and substrate−molecule interactions. Molecule−substrate interactions will set limits to the mobility of the adsorbed molecules and may alter the electronic structure of the absorbed molecules, or the electronic states at the surfaces may become locally perturbed by the adsorbate. 60 A consequence is that the established concepts of solution-based coordination chemistry cannot be applied without appropriate modification. The substrate thus becomes an additional parameter to control the adsorption energy of the molecules and, hence, their diffusivity at surfaces. An intriguing demonstration of this effect is the self-assembly of porphyrins, which are decoupled from their metal substrate by insulating NaCl layers of varying thickness. 23 The interaction was shown to be dependent on the NaCl layers, and the thicker the NaCl the weaker the interaction and the more delayed the onset of network formation. The occupation of the center ring of the porphyrin may affect the molecular adsorption at surfaces. As an example, free-base or Cu-incorporated porphyrin molecules show different arrangements along step edges on Cu(100) surfaces. While 2H-TBPP bridges over the step edges, Cu-TBPP sits on either side of step edges. 27 In contrast, no difference in the network architecture was found for differently metalated TPP on Ag(111). 57 Such a subtle dependence of adsorption site on metal incorporation, if fully understood, may become useful to control the self-assembly or the properties of the molecules on surfaces.The goal...

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“…52 [371]. The 2HTPP monolayer spectrum shows two components: One for the iminic nitrogen (-N ¼ ) at lower binding energy (398.2 eV) and another for pyrrolic nitrogen (-NH-) at higher binding energy (400.1 eV) [702]. Upon deposition of Fe atoms, the two 2HTPP related peaks are increasingly replaced by a single peak at 398.7 eV, which indicates the formation of FeTPP, because the four nitrogen atoms are chemically equivalent in the complex.…”

Section: On-surface Metalation With Post-deposited Metal Atomsmentioning

confidence: 99%

Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

569

586

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The photoelectron spectra of tetraphenylporphine and some metallotetraphenylporphyrins

Cited by 91 publications

References 10 publications

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Self-Assembly and Properties of Nonmetalated Tetraphenyl-Porphyrin on Metal Substrates

Surface chemistry of porphyrins and phthalocyanines

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