XANES Spectroscopic Studies of Evaporated Porphyrin Films: Molecular Orientation and Electronic Structure

Narioka, S.; Ishii, Hisao; Ouchi, Yukio; Yokoyama, Toshihiko; Ohta, Toshiaki; Seki, Kazuhiko

doi:10.1021/j100004a038

Cited by 69 publications

(59 citation statements)

References 12 publications

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“…First, there is a clear dependence from the experimental geometry, that may be given either by band dispersion or by polarization dependence in the photoemission initial state. Second, the peak at ~ 2.5 eV, that was recognized as the highest occupied molecular orbital (HOMO) in other photoemission experiments [8], has a shoulder at lower binding energy, suggesting that this shoulder is the real HOMO emission.…”

Section: Resultsmentioning

confidence: 93%

“…Despite the interest and the huge amount of works on this family of molecules, there are only very few experimental articles on the growth via molecular beam epitaxy of thin films on various substrates and the investigation of the electronic properties using a direct probe like photoemission spectroscopy [8][9][10]. This paper focuses on an experimental study of the growth and electronic properties of a prototype molecule of this family, namely Zn-tetra-phenyl-porphyrin (ZnTPP), in the form of multilayer films on Si(111).…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)

Cudia¹,

Vilmercati²,

Larciprete³

et al. 2006

Surface Science

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The electronic properties and the molecular orientation of Zn-tetraphenyl-porphyrin films deposited on Si(111) have been investigated using synchrotron radiation. For the first time we have revealed and assigned the fine structures in the electronic spectra related to the HOMOs and LUMOs states. This is particularly important in order to understand the orbital interactions, the bond formation and the evolution of the electronic properties with oxidation or reduction of the porphyrins in supramolecular donor-acceptor complexes used in photovoltaic devices.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)

Cudia¹,

Vilmercati²,

Larciprete³

et al. 2006

Surface Science

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“…In the past, this has led many groups to dismiss C K-edge spectra for the orientational analysis of phenyl-substituted porphyrins. 26 However careful inspection and assignment of each π* resonance does yield orientational information for both ring systems. 31 …”

Section: Resultsmentioning

confidence: 99%

Deprotection, Tethering, and Activation of a One-Legged Metalloporphyrin on a Chemically Active Metal Surface: NEXAFS, Synchrotron XPS, and STM Study of [SAc]P−Mn(III)Cl on Ag(100)

et al. 2009

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The structural and reactive properties of the acetyl-protected "one-legged" manganese porphyrin[SAc]P-Mn(III)Cl on Ag(100) have been studied by NEXAFS, synchrotron XPS and STM.Spontaneous surface-mediated de-protection occurs at 300 K accompanied by spreading of the resulting thio-tethered porphyrin across the metal surface. Loss of the axial chlorine ligand occurs at 498 K, without any de-metallation of the macrocycle, leaving the Mn center in a low co-ordination state. At low coverages the macrocycle is markedly tilted towards the silver surface, as is the phenyl group that forms part of the tethering "leg". In the monolayer region a striking transition occurs whereby the molecule rolls over, preserving the tilt angle of the phenyl group, strongly increasing that of the 2 macrocycle, decreasing the apparent height of the molecule and decreasing its footprint, thus enabling closer packing. These findings are in marked contrast with those previously reported for the corresponding more rigidly bound four-legged porphyrin [JACS 2009[JACS , 126, 1910 suggesting that the physico-chemical properties and potential applications of these versatile systems should be strongly dependent on the mode of tethering to the surface.

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“…[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.…”

Section: Introductionmentioning

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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XANES Spectroscopic Studies of Evaporated Porphyrin Films: Molecular Orientation and Electronic Structure

Cited by 69 publications

References 12 publications

Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)

Electronic structure and molecular orientation of a Zn-tetra-phenyl porphyrin multilayer on Si(111)

Deprotection, Tethering, and Activation of a One-Legged Metalloporphyrin on a Chemically Active Metal Surface: NEXAFS, Synchrotron XPS, and STM Study of [SAc]P−Mn(III)Cl on Ag(100)

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

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