Polarized total-reflection x-ray absorption fine structure for self-assembled monolayer of zinc porphyrin at air–water interface

Abstract

Articles you may be interested inNovel cyanoterphenyl self-assembly monolayers on Au(111) studied by ellipsometry, x-ray photoelectron spectroscopy, and vibrational spectroscopies Polarized near-edge x-ray-absorption fine structure spectroscopy of C 60 -functionalized 11-amino-1-undecane thiol self-assembled monolayer: Molecular orientation and Evidence for C 60 aggregation J. Chem. Phys. 122, 154703 (2005); 10.1063/1.1880952Dipole-induced structure in aromatic-terminated self-assembled monolayers-A study by near edge x-ray absorption fine structure spectroscopy Detection of phase transition of monolayers at the air-water interface by compression using Maxwell displacement current and optical second harmonic generation Orientational order study of monolayers at the air-water interface by Maxwell-displacement current and optical second harmonic generation

Soft-Photoconversion Using Floating Self-Assembled Crystalline Films of Porphyrin Nanostructures

“…1 This ability to resist dimerisation, or more extensive aggregation, in aqueous solutions is attributed to the penta-coordination of the zinc atom in ZnTPPc, with a water molecule occupying the axial position. [2][3][4][5] The axial water ligand prevents close approach of porphyrin molecules. More subtly, axial coordination of metalloporphyrins leads to the metal ion being displaced from the porphyrin ring plane.…”

Extended X-ray Absorption Fine Structure of Copper(II) Complexes at the Air-Water Interface by a Polarized Total-Reflection X-ray Absorption Technique

“…In the case of zinc(II) porphyrins, for instance, the peak at the Zn Kedge disappears when they are dissolved in ethyl acetate owing to an effective axial coordination of solvent molecules to the zinc center. 19,20 On the other hand, one can observe a weak peak at 8985 eV in the XANES spectra for solutions of copper(II) porphyrin derivatives, indicating the presence of weak axial coordination of the solvent molecules.…”

“…The planar molecules of meso-substituted porphyrin derivatives, 5,10,15,20-tetraphenylporphyrinato zinc(II) (ZnTPP) and 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrinato zinc(II) (ZnTPPC) were found to orient roughly parallel to the solution surface. 19,20 On the other hand, zinc(II) protoporphyrin IX (ZnPP) with hydrophilic carboxyl groups at one side of the molecule was standing-up with respect to the solution surface. 20 The axial coordination behavior of the metalloporphyrin plays an important role in the molecular recognition properties in sensor applications, [21][22][23] the self-assembling of supramolecular structures [24][25][26] and monolayer formations at the air-water interface.…”

“…13 For a solid surface, the polarization-dependent XAFS technique has been utilized to elucidate a well-organized structure such as thin-layer materials and coordination sites of adatoms on crystals. [14][15][16][17][18] Recent applications of the polarized TR-XAFS method have revealed the specific solvation structure of zinc(II) porphyrins at the air-water interface, 19,20 in which the X-ray absorption near edge structure (XANES) exhibited a significant difference depending on the polarization of X-rays. A pre-edge peak, which is known to correspond to the 1sAE4pz transition for a square-planar metal complex without axial coordination, was observed at the Zn K-edge, and it was concluded that the axial coordination sites of the zinc porphyrin molecules examined were not fully hydrated at the air-water interface.…”

Communication: Coordination structure of bromide ions associated with hexyltrimethylammonium cations at liquid/liquid interfaces under potentiostatic control as studied by total-reflection X-ray absorption fine structure

“…6 The polarization dependences of TR-XAFS spectrum have also provided valuable insights into the molecular orientation and coordination structure of metal complexes at soft interfaces. [7][8][9] Recently, the polarized TR-XAFS method was applied to liquid/liquid interfaces, in which a partial dehydration of the axial sites of anionic zinc(II) porphyrin spontaneously adsorbed at the heptane/water interface was directly observed from the polarization dependences of X-ray absorption near-edge structure (XANES) involving a 1s-4p z transition for a square planar metal complex. 10 The interfacial association between alkylammonium surfactants and bromide ions was also measured at the heptane/water interface.…”