Effective bimetallic composite catalysts for the synthesis of arylated furans and thiophenes in aqueous media

Chemistry of Heterocyclic Compounds - N-(4,6-Dimethylpyrimidin-2-yl)-5-phenylisoxazole-3-carboxamide was used as a ligand for obtaining bimetallic boron-containing heterogeneous catalysts...     

On Linear Transformations of Intersections

Set-Valued and Variational Analysis - For any linear transformation and two convex closed sets, we provide necessary and sufficient conditions for the transformation of the intersection of the sets...     

Between Aromatic and Quinoid Structure: A Symmetrical UV to Vis/NIR Benzothiadiazole Redox Switch

Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches.     

Introducing tox-Profiles of Chemical Reactions

In this Essay, we present a critical analysis of two common practices in modern chemistry—that is, of using speculations about the “greenness” and “nontoxicity” of developed synthesis procedures and of a priori labelling various compounds derived from natural sources as being environmentally safe. We note that every organic molecule that contains functional groups should be biologically active. Thus, analysis of the particular greenness and the potential environmental impact of a given chemical process should account for the biological activity of all its components in a measureable (rather than empirical) way. We highlight the necessity of clarifying discussions on biological activity and toxicity and propose possible ways of introducing tox-Profiles as a reliable overview of the overall toxicity of chemical reactions.     

Biological assays and theoretical density functional theory calculations of Rh(I), Ir(III), and Ru(II) complexes of chiral phosphinite ligand

Four metal complexes, IL-OPPh₂-Ru-p-cymene (3) , IL-OPPh₂-Ru-benzene (4) , IL-OPPh₂-Ir-Cp* (5) , IL-OPPh₂-Rh-COD (6) , have been evaluated for in vitro antioxidant activity such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power activity. Maximum scavenging activity (71.43%) was obtained with IL-OPPh₂-Ru-p-cymene, whereas IL-OPPh₂-Rh-COD showed the highest reducing power ability. The complexes were also studied for their antimicrobial activity against three Gram-positive and three Gram-negative bacteria. In addition, DNA binding of the complexes was evaluated using calf thymus DNA. Both Ru(II) complexes exhibited good DNA-binding activity while the other complexes did not have any activity. Furthermore, ab initio quantum calculations of four complexes were also carried out using density functional theory to better understand their chemical behaviors.     

Fused-Pentagon Isomers of C60 Fullerene Isolated as Chloro and Trifluoromethyl Derivatives

The carbon cage of buckminsterfullerene I_h-C₆₀, which obeys the Isolated-Pentagon Rule (IPR), can be transformed to non-IPR cages in the course of high-temperature chlorination of C₆₀ or C₆₀Cl₃₀ with SbCl₅. The non-IPR chloro derivatives were isolated chromatographically (HPLC) and characterized crystallographically as ¹⁸⁰⁹C₆₀Cl₁₆, ¹⁸¹⁰C₆₀Cl₂₄, and ¹⁸⁰⁵C₆₀Cl₂₄, which contain, respectively two, four, and four pairs of fused pentagons in the carbon cage. High-temperature trifluoromethylation of the chlorination products with CF₃I afforded a non-IPR CF₃ derivative, ¹⁸⁰⁷C₆₀(CF₃)₁₂, which contains four pairs of fused pentagons in the carbon cage. Addition patterns of non-IPR chloro and CF₃ derivatives were compared and discussed in terms of the formation of stabilizing local substructures on fullerene cages. A detailed scheme of the experimentally confirmed non-IPR C₆₀ isomers obtained by Stone–Wales cage transformations is presented.     

Room temperature MgI2-catalyzed Friedel–Crafts reaction between electron-rich (het)arenes and ethyl glyoxylate

Magnesium iodide-catalyzed addition of electron-rich (het)arenes to ethyl glyoxylate proceeds at room temperature with high chemoselectivity to afford ethyl 2-(het)aryl- 2-hydroxyacetates in yields up to 95%.     

The modes of combustion of copper nanopowders

It was shown that the synthesis of Cu nanopowder by thermal decomposition afforded chemically purer (without oxides) and finer (specific surface value ～45 m2 g^?1) product than the synthesis by chemical reduction. The latter method leads to pyrophoric nanopowders containing detectable amounts of copper oxides.     

Factorized S-matrices in two dimensions as the exact solutions of certain relativistic quantum field theory models

The general properties of the factorized S-matrix in two-dimensional space-time are considered. The relation between the factorization property of the scattering theory and the infinite number of conservation laws of the underlying field theory is discussed. The factorization of the total S-matrix is shown to impose hard restrictions on two-particle matrix elements: they should satisfy special identities, the so-called factorization equations. The general solution of the unitarity, crossing and factorization equations is found for the S-matrices having isotopic O(N)-symmetry. The solution turns out to have different properties for the cases N = 2 and N 3. For N = 2 the general solution depends on one parameter (of coupling constant type), whereas the solution for N 3 has no parameters but depends analytically on N. The solution for N = 2 is shown to be an exact soliton S-matrix of the sine-Gordon model (equivalently the massive Thirring model). The total S-matrix of the model is constructed. In the case of N 3 there are two “minimum” solutions, i.e., those having a minimum set of singularities. One of them is shown to be an exact S matrix of the quantum O(N)-symmetric nonlinear σ-model, the other is argued to describe the scattering of elementary particles of the Gross-Neveu model.