Palladium-Mediated Stepwise Assembly of Three-Dimensional Organized Multiporphyrin Arrays Directly on Solid Substrates

Abstract

A palladium-mediated assembling strategy was developed to construct organized, three-dimensional multiporphyrin arrays, wherein layers of multiporphyrin arrays can be embedded via a Py-Pd-Py coordination unit directly on solid substrates. Multilayers of the multiporphyrin arrays were characterized by use of X-ray photoelectron, UV-vis, and fluorescence spectroscopy. A linear increase was observed for the absorption intensity of the Soret band of porphyrins or the π-π* charge transition with the layer numbers of porphyrins or palladium ions assembled. The surface density of (Zn)TPyP molecules in one layer of multiporphyrin arrays was estimated to be in the range of 1.9-2.4 × 10 -10 mol/cm 2 . The orientation angle of the porphyrin macrocycles was in the range of 55-60°. A schematic model for the multiporphyrin arrays was proposed based on the spectral analysis, orientation angle, and film thickness from atomic force microscopy measurement. These Pd-mediated multiporphyrin arrays showed high thermal and chemical stability. They were stable in air and commonly used organic solvents. Moreover, no significant absorption spectral change was recorded in a temperature up to 150 °C and in an aqueous solution with pH < 2.

Pd(II)-Directed Encapsulation of Hydrogenase within the Layer-by-Layer Multilayers of Carbon Nanotube Polyelectrolyte Used as a Heterogeneous Catalyst for Oxidation of Hydrogen

“…These curves revealed a broad absorption band between 200 and 500 nm, which could be attributed to the π−π* and n−π* electron transfer of the Pd− Py coordination unit, H 2 ase and MWNTs. 39 The absorption intensity at 290 nm was proportional with the layer numbers assembled (see the graph inserted in Figure 5), which indicated that similar amounts of the nanolinkers and Na 2 PdCl 4 connectors were assembled for each bilayer. A close inspection of the absorption increase could find a relatively larger increase for the coordination of the PdCl 4 2− ions, together with a smaller one for the coordination or adsorption of the bionanocomposites.…”

“…A possible reason may be that the PdCl 4 2− ions could coordinate with pyridine substituents more efficiently than those reported previously at the interfaces. 39 The assembling process was monitored by measuring the absorption spectra, XPS, FE-SEM, and AFM images as described below. Figure 5 shows the absorption spectra for the (Pd/MWNTPVPMe@H 2 ase) n LBL multilayers on the quartz surface after each assembly of the connector of Na 2 PdCl 4 and the nanolinker of MWNT-PVPMe@H 2 ase.…”

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O2

“…Other nanoscaled materials of porphyrins, such as tubes, rods, and crystals, can be formed from simple commercially available compounds or from more complex molecular designs. [18, 87] Self-assembled porphyrinic materials generally require specifically designed recognition motifs in predefined geometries to affect specific architectures. Conversely, the construction of self-organized materials, such as ONPs, does not require complex exocyclic moieties.…”

Supramolecular Organization of Porphyrins and Phthalocyanines by Use of Biomimetic Coordination Methodology

“…174 Imahori and coworkers employed a supramolecular approach to organize porphyrin-fullerene doublecable structures (Scheme 65). 183 Alternating deposition of pyridylporphyrin 137 and K 2 PdCl 4 through pyridyl-to-Pd coordination, the method originally developed by Qian et al, 184 followed by incorporation of fullerene 138 through pyridylto-zinc coordination gave a surface-oriented double-cable structure on the SnO 2 electrode, that exhibited enhanced photobipolar properties. Employing specific interactions of proteins, straightforward supramolecular assemblies were obtained.…”