Ability Of Pd Research Articles

Insights into microwave‐promoted synthesis of 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives catalyzed using new Pd (II),Cu (II),VO (II), and Ag(I) complexes as a heterogeneous catalyst and computational studies

Four novel Pd (II), Cu (II), VO (II), and Ag(I) complexes were prepared from benzimidazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, DFT/time‐dependent DFT computations were performed applying (B3LYP/6‐311++G[d,p]/aug‐cc‐pVTZ/aug‐cc‐pVTZ‐PP) level in order to investigate the electronic behavior of the compounds. These results demonstrated good agreement with the experimental data. Computational data discriminate Pd (II) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole was carried out under mild reaction conditions by microwave irradiation. All reaction conditions were optimized among those variable Lewis acid catalysts in comparison with our new complexes. DOBPAPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds over z‐axis and supported by theoretical aspects.

Metal coordination to a deep cavitand promotes binding selectivities in water

One goal of supramolecular chemistry is the creation of synthetic receptors that have a high affinity for hydrophilic molecules in water. We found that cavitands with upper rims extended by pyridyl groups coax hydrophilic guests into the cavity where they are shielded from the aqueous environment. The ability of Pd(II) to coordinate adjacent pyridyl groups leads to increased selectivity for highly hydrophilic solvent molecules such as acetone, 1,4-dioxane and tetrahydrofuran in water. Analysis of the binding behavior indicated that metal-coordination restricts the container entrance, shrinks the effective cavity volume and increases the energetic barrier to guest exchange.

Efficient and recoverable novel pyranothiazol Pd (II), Cu (II) and Fe(III) catalysts in simple synthesis of polyfunctionalized pyrroles: Under mild conditions using ultrasonic irradiation

AbstractThree novel Pd (II), Cu (II), and Fe (III) complexes were prepared from thiazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained by Material Studio Package via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, crystal surface properties in the packing system were studied using the Crystal explorer program, to evaluate the extent of contact between surfaces. Computational data discriminate Pd (II)‐thiazole (HYHPd) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize polyfunctionalized pyrrole derivatives using ultrasonic irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for aromatic aldehyde, aromatic amine, acetylacetone, and nitromethane was carried out under mild reaction conditions by ultrasonic irradiation. All reaction conditions were optimized among that variable Lewis acid catalysts in comparison to our new complexes. HYHPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero‐catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds overzaxis and supported by theoretical aspects.

Spectromicroscopy study of the dynamics of submonolayer Pd on a polycrystalline Ni surface

The lateral distribution of submonolayer Pd deposited at room temperature on the surface of a polycrystalline Ni sample has been studied with scanning photoelectron microscopy (SPEM). The Ni sample consisted of differently oriented crystal grains, as evidenced by low-energy electron microscopy and micro-low-energy electron diffraction measurements and by SPEM Ni $3p$ maps showing surface topography. The elemental contrast of the SPEM Pd $3d$ images have revealed that the different grains of the polycrystalline surface show different activity, resulting in differences in the local Pd concentrations. The chemical state of Pd was well described by the Pd ${3d}_{5/2}$ spectra. They consisted of two components interpreted in terms of adsorbed Pd species (Pd ${3d}_{5/2}$ binding energy of 336.0 eV) and Pd embedded in the Ni a surface lattice, forming surface ${\mathrm{Pd}}_{x}{\mathrm{Ni}}_{y}$ alloy (Pd ${3d}_{5/2}$ binding energy at 335.5 eV). Chemical imaging in terms of these Pd ${3d}_{5/2}$ components confirmed that the ability of Pd to alloy or form clusters also depends on the individual structure of the grains on the polycrystalline Ni surface.

Bacterial DNA reactivity of the novel antitumor antibiotics PD 114,759 and PD 115,028 (veractamycins A and B).

The novel antitumor antibiotics PD 114,759 and PD 115,028 were evaluated for their ability to cause repairable DNA damage and the induction of SOS functions in bacterial systems. PD 114,759 and PD 115,028 were preferentially toxic to DNA repair-defective Escherichia coli WP100 uvrA recA in comparison to wild-type E. coli WP2 at concentrations of 10 approximately 30 micrograms/ml in agar diffusion assays. Both compounds were inducers of cell filamentation and prophage lambda (two E. coli SOS functions) at concentrations of 0.1 approximately 1 microgram/ml. In addition, the ability of PD 114,759 and PD 115,028 to retain their filamentation-inducing effects under both aerobic conditions and anaerobic conditions suggests that a bioreductive, rather than an oxygen-requiring, mechanism is involved in the DNA-reactive effects of these agents.

The Effects of Interfacial SiO2 on Pd2Si Formation

We investigated the effects of thin Si 16 O 2 and Si 18 O 2 interfacial layers on Pd 2 Si formation using He + backscattering spectrometry and the 16 O(d,α) 14 N and 18 O(p, α) 15 N nuclear reactions. SiO 2 films from 10 to 50 Å thick were formed on Si<100> substrates by 16 O 2 or 18 O 2 plasma oxidation. Nickel, palladium or platinum films from 1000 to 1400 Å thick were then evaporated onto this SiO 2 layer and the samples were annealed in vacuum at temperatures ranging from 250 to 750 °C. The minimum temperature necessary for Pd 2 Si formation is approximately 400°C for about 24 Å of SiO 2 compared with 600°C for Pt 2 Si and 650°C for Ni 2 Si formation. The ability of Pd 2 Si to form in the presence of an SiO 2 interfacial layer is compared with that of Ni 2 Si and Pt 2 Si and is interpreted using the relative mobilities of the metals in SiO 2 and the redistribution of the 18 O during silicide formation.