One-pot deposition of palladium on hybrid TiO2 nanoparticles and catalytic applications in hydrogenation

One-pot deposition of Pd onto TiO(2) has been achieved through directly contacting palladium(II) salt with nanosized functionalized TiO(2) support initially obtained by sol-gel process using titanium isopropoxide and citric acid. Citrate groups act as functional moieties able to directly reduce the Pd salt avoiding any further reducing treatment. Various palladium salts (Na(2)PdCl(4) and Pd(NH(3))(4)Cl(2)·H(2)O) and titanium to citrate (Ti/CA) ratios (20, 50, and 100) were used in order to study the effect of the nature of the precursor and of the citrate content on the final Pd particle size and catalytic properties of the as-obtained Pd/TiO(2) systems. Characterization was performed using N(2) adsorption-desorption isotherms, ICP-AES, FTIR, XRD, XPS, and TEM. The as-obtained hybrid Pd/TiO(2) catalysts were tested in the selective hydrogenation (HYD) of an α,β-unsaturated aldehyde, i.e. cinnamaldehyde. Citrate-free Pd/TiO(2)-based catalysts present lower selectivity into saturated alcohol. However, citrate-functionalized Pd/TiO(2) catalyst seems to control the selectivity, the particle size and dispersion of Pd NPs leading to high intrinsic activity.     

Microwave Michaelis–Becker synthesis of diethyl phosphonates,tetraethyl diphosphonates,and their total or partial dealkylation

Diethyl phosphonates and tetraethyl alkyldiphosphonates were efficiently and rapidly prepared via the Michaelis–Becker reaction, under microwave irradiation. These compounds were then hydrolyzed to phosphonic and diphosphonic acids or selectively monodealkylated to give monoesters of phosphonic acids and symmetrical diethyl esters of diphosphonic acids. These reactions were also achieved rapidly in satisfactory yields with microwave methodology. This methodology was applied with success to the functionalization of a polymer resin. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:369–377, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20561     

DBU-Catalyzed, facile and efficient method for synthesis of spirocyclic 2-oxindole derivatives with incorporated 6-amino-4H-pyridazines and fused derivatives via [3+3] atom combination

3-Cyanomethylidene oxindole derivatives were prepared in excellent yields utilizing DBU-promoted Knoevenagel condensation of isatin derivatives with active methylene reagents. The isolated products were then reacted with azaenamines via a DBU-promoted Michael addition to yield spirocyclic 2-oxindole derivatives with incorporated 6-amino-4H-pyridazines and their fused derivatives.     

A New Non-centrosymmetric Microporous Fluorinated Iron Phosphate: Structural Elucidation,Spectroscopic Study and Hirshfeld Surface Analysis

The crystal structure of a new non-centrosymmetric microporous fluorinated iron phosphate, (H₃O)₂[Fe₄(H₂O)₂F₄(PO₄)₂(HPO₄)₂](H₂O), was determined by single crystal X-ray diffraction analysis and the result reveals that it belongs to the orthorhombic system with four molecules in the unit cell(space group P2₁2₁2₁). Thus, the complex was characterized by powder X-ray diffraction, spectroscopic techniques(Fourier transform infrared and Fourier transform Raman) and ¹⁹F MAS NMR. The elemental analysis of the sample was also carried out. The chiral inorganic sheets, which stacked along[100] showed the presence of FeF₂O₄ as well as FeF₂O₃H₂O octahedra, PO₄ besides HPO₄ tetrahedra, hydronium ions(H₃O⁺) and isolated water molecules. Hirshfeld surface analysis, especially d_nom surface and fingerprint plots, were used for decoding the intermolecular interactions in the crystal network and the contribution of component units for the construction of the 3D architecture. From the Hirshfeld surfaces and 2D fingerprint analysis, it was found that the subtle interactions, such as H…H associating the third intense interaction of all intercontacts, provide extra stabilization in addition to the presence of the strong hydrogen bonds mentioned above.     

2‐Cyano‐N‐(thiophen‐2‐yl)acetamide in Heterocyclic Synthesis: Synthesis and Antibacterial Screening of Novel Pyrido[1,2‐a]thieno[3,2‐e]pyrimidine‐2‐carboxylate Moieties

A novel series of interesting 6,8‐dicyanopyrido[1,2‐a]thieno[3,2‐e]pyrimidine‐2‐carboxylate compounds were prepared via the reaction of readily accessible 2‐cyano‐N‐(thiophen‐2‐yl)acetamide with arylidene malononitriles in pyridine in the presence of piperidine. Biological screening of the tested compounds as antibacterial agents was also studied.     

Reactive Polymer Based Colloids for Biomedical Applications

Summary: This short review aimed to give to the reader brief applications of polymer colloids in biomedical area and principally in medical diagnostics. Colloidal polymer particles are mainly used as solid supports, as label for biomolecules reactions detection, and as a carrier. The elaboration of appropriate colloids is reached via numerous processes such as polymerization in dispersed media (dispersion, emulsion, precipitation, miniemulsion polymerizations) or as physico-chemical methodologies (i.e., self-assembly). After a short introduction, some particles elaborations are presented and their applications are briefly described and illustrated.     

Pancyclic and panconnected line graphs

Let G be a graph of order n ? 3. We prove that if G is k-connected (k ? 2) and the degree sum of k + 1 mutually independent vertices of G is greater than 1/3(k + 1)(n + 1), then the line graph L(G) of G is pancyclic. We also prove that if G is such that the degree sum of every 2 adjacent vertices is at least n, then L(G) is panconnected with some exceptions.     

Palladium-ceria catalysts: Metal-support interactions and reactivity of palladium in selective hydrogenation of but-1-yne

The influence of palladium-ceria interactions on the reactivity of palladium in but-1-yne hydrogenation has been investigated and compared with previous results obtained on alumina. The main differences from Pd-alumina catalysts are (i) the enhancement of the turnover frequency ascribed to electron transfer from ceria to Pd, (ii) the diminution of the selectivity to but-1-ene, attributed to hydrogen spillover.