Direct sulfenylation of acetone with benzothiazolesulfenamides to benzothiazolylthio-substituted alkylaminopropene: synthesis and application

N-Substituted derivatives of 2-benzothiazolesulfenamides give high yields of 1-(2′-benzothiazolylthio)-2-alkylaminoprop-1-ene and 1,1-bis-(2′-benzothiazolylthio)-2-alkylaminoprop-1-ene in a reaction with acetone in the temperature range from 56°C to 70°C and in the presence of a small amount of water. The α-sulfenylated carbonyl product, 2′-benzothiazolylthiopropan-2-one, is supposed to be an intermediate of this one-pot synthesis. 1,1-Bis-(2′-benzothiazolylthio)-2-tert-butylaminoprop-1-ene has been proved an accelerator of sulfur curing of rubber composites with high processing safety.     

Electroactive self-assembled monolayers that permit orthogonal control over the adhesion of cells to patterned substrates

This article describes an electroactive substrate that displays two independent dynamic functions for controlling the adhesion of cells. The approach is based on self-assembled monolayers on gold that are patterned into regions presenting the Arg-Gly-Asp peptide cell adhesion ligand. The patterned regions differ in the electrochemical properties of the linkers that tether the peptides to the monolayer. In this work, three distinct chemistries are employed that provide for release of the ligand on application of a negative potential, release of the ligand on application of a positive potential, and no change in response to a potential. Cells were allowed to attach to a monolayer patterned into circular regions comprising the three chemistries. Treatment with electric potentials of 650 or -650 mV resulted in the selective release of adherent cells only from regions that display the relevant electroactive groups. This example establishes the preparation of dynamic substrates with multiple functions and will be important to preparing model cultures derived from multiple cell types, with control over the temporal interactions of each cell population.     

Equitorsion holomorphically projective mappings of generalized Kählerian space of the first kind

In this paper we define generalized Kählerian spaces of the first kind (\(G_1^K N\)) given by (2.1)–(2.3). For them we consider hollomorphically projective mappings with invariant complex structure. Also, we consider equitorsion geodesic mapping between these two spaces (\(G_1^K N\) and \(G_1^{\bar K} N\)) and for them we find invariant geometric objects.     

Smooth dependence on data of solutions and contact regions for a Signorini problem

We prove that the solutions to a 2D Poisson equation with unilateral boundary conditions of Signorini type as well as their contact intervals depend smoothly on the data. The result is based on a certain local equivalence of the unilateral boundary value problem to a smooth abstract equation in a Hilbert space and on an application of the Implicit Function Theorem to that equation.     

Reactivity of an N,N‐Chelated Germylene Toward Substituted Alkynes,Alkenes, and Allenes

Treatment of N,N‐chelated germylene [(iPr)₂NB(N‐2,6‐Me₂C₆H₃)₂]Ge ( 1 ) with ferrocenyl alkynes containing carbonyl functionalities, FcC≡CC(O)R, resulted in [2+2+2] cyclization and formation of the respective ferrocenylated 3‐Fc‐4‐C(O)R‐1,2‐digermacyclobut‐3‐enes 2 – 4 [R = Me ( 2 ), OEt ( 3 ) and NMe₂ ( 4 )] bearing intact carbonyl substituents. In contrast, the reaction between 1 and PhC(O)C≡CC(O)Ph led to activation of both C≡C and C=O bonds producing bicyclic compound containing two five‐membered 1‐germa‐2‐oxacyclopent‐3‐ene rings sharing one C–C bond, 4,8‐diphenyl‐3,7‐dioxa‐2,6‐digermabicyclo[3.3.0]octa‐4,8‐diene ( 5 ). With N‐methylmaleimide containing an analogous C(O)CH=CHC(O) fragment, germylene 1 reacted under [2+2+2] cyclization involving the C=C double bond, producing 1,2‐digermacyclobutane 6 with unchanged carbonyl moieties. Finally, 1 selectively added to the terminal double bond in allenes CH₂=C=CRR′ giving rise to 3‐(=CRR′)‐1,2‐digermacyclobutanes [R/R′ = Me/Me ( 7 ), H/OMe ( 8 )] bearing an exo‐C=C double bond. All compounds were characterized by ¹H, ¹³C{¹H} NMR, IR and Raman spectroscopy and the molecular structures of 3 , 4 , 5 , and 8 were established by single‐crystal X‐ray diffraction analysis. The redox behavior of ferrocenylated derivatives 2 – 4 was studied by cyclic voltammetry.     

Benzenoid rings resonance energies and local aromaticity of benzenoid hydrocarbons

In this article, we consider partitioning of the analytical expression for resonance energy (RE) in smaller benzenoid hydrocarbons, to individual benzenoid rings of polycyclic molecules. The analytical expression for molecular RE, available since 1976, is given by the count of all linearly independent conjugated circuit in all Kekulé structures in a molecule. Analytical expression for local ring RE (RRE) is given by counting all linearly independent conjugated circuits involving single benzenoid ring in all Kekulé structures, which when added, gives the molecular RE. If for benzene ring the RRE is taken to be 1.000, rings in polycyclic benzenoid hydrocarbons have their ring RRE, which give the degree of their local aromaticity, smaller than 1.000. The difference to 1.000 is a measure of the similarity of a ring to benzene in this one-dimensional (1-D) representation of local aromaticities of benzenoid hydrocarbons. The plot of RRE against the distance of the same ring from benzene in the Local Aromaticity Map, in which benzenoid rings are characterized ring bond orders and average variations of adjacent CC bonds, shows linear correlation (with r = 0.91), reducing the local aromaticity in benzenoid hydrocarbons to 1-D molecular property. © 2018 Wiley Periodicals, Inc.     

Benzoisothiazole-1,1-dioxide-based synthetic receptor for zinc ion recognition in aqueous medium and its interaction with nucleic acids

Benzoisothiazole-1,1-dioxide-based synthetic receptor was prepared by two step synthesis in 92 % overall yield. Its applicability for the determination of Zn(II) and interction with nucleic acids was studied by absorption spectroscopy. Obtained data, specifically low limit of detection, 0.15 µM (R² = 0.9933), showed the high potential of the tested structure motif for the recognition and determination of Zn(II) ions in aqueous media (water:DMSO; 99:1 (ν/ν)). Alone receptor displayed orderly strongly RNA affinity. Value of LogK was 6.1 and 4.9 for its complex (1:1) with RNA and DNA, respectively. Nevertheless, in presence of complexed Zn(II) ions, its DNA affinity (represent by K, LogK = 5.7) strongly grow to near value obtained for its interaction with RNA. On the other hand, its RNA affinity (LogK = 5.9) displayed not significantly change in the presence of complexed one.     

Release of Formic Acid from Copper Formate: Hydride,Proton-Coupled Electron and Hydrogen Atom Transfer All Play their Role

Although the mechanism for the transformation of carbon dioxide to formate with copper hydride is well understood, it is not clear how formic acid is ultimately released. Herein, we show how formic acid is formed in the decomposition of the copper formate clusters Cu(II)(HCOO)₃⁻ and Cu(II)₂(HCOO)₅⁻. Infrared irradiation resonant with the antisymmetric C−O stretching mode activates the cluster, resulting in the release of formic acid and carbon dioxide. For the binary cluster, electronic structure calculations indicate that CO₂ is eliminated first, through hydride transfer from formate to copper. Formic acid is released via proton-coupled electron transfer (PCET) to a second formate ligand, evidenced by close to zero partial charge and spin density at the hydrogen atom in the transition state. Concomitantly, the two copper centers are reduced from Cu(II) to Cu(I). Depending on the detailed situation, either PCET or hydrogen atom transfer (HAT) takes place.     

Decomposition of Copper Formate Clusters: Insight into Elementary Steps of Calcination and Carbon Dioxide Activation

The decomposition of copper formate clusters is investigated in the gas phase by infrared multiple photon dissociation of Cu(II)_n(HCO₂)_2n+1⁻, n≤8. In combination with quantum chemical calculations and reactivity measurements using oxygen, elementary steps of the decomposition of copper formate are characterized, which play a key role during calcination as well as for the function of copper hydride based catalysts. The decomposition of larger clusters (n > 2) takes place exclusively by the sequential loss of neutral copper formate units Cu(II)(HCO₂)₂ or Cu(II)₂(HCO₂)₄, leading to clusters with n=1 or n=2. Only for these small clusters, redox reactions are observed as discussed in detail previously, including the formation of formic acid or loss of hydrogen atoms, leading to a variety of Cu(I) complexes. The stoichiometric monovalent copper formate clusters Cu(I)_m(HCO₂)_m+1⁻, (m=1,2) decompose exclusively by decarboxylation, leading towards copper hydrides in oxidation state +I. Copper oxide centers are obtained via reactions of molecular oxygen with copper hydride centers, species containing carbon dioxide radical anions as ligands or a Cu(0) center. However, stoichiometric copper(I) and copper(II) formate Cu(I)(HCO₂)₂⁻ and Cu(II)(HCO₂)₃⁻, respectively, is unreactive towards oxygen.     

A wet-chemical route for the preparation of Ni–BaCe0.9Y0.1O3 − δ cermet anodes for IT-SOFCs

Nano-sized BaCe_0.9Y_0.1O_3 ? δ (BCY10) protonic conductor powders were used to prepare Ni-BCY10 cermets for anode-supported intermediate temperature solid oxide fuel cells. A new wet-chemical route was developed starting from Ni nitrates as precursors for NiO. BCY10 powders were suspended in a Ni nitrate aqueous solution that was evaporated to allow NiO precipitation on the BCY grains, obtaining NiO-BCY10 cermets. To obtain the final Ni-BCY10 anodes, pellets were reduced in dry H₂ at 700 °C. The structural and microstructural properties of the pellets were investigated using X-ray diffraction analysis and field emission scanning electron microscopy. A homogeneous dispersion of perovskite and nickel phases was observed. The chemical stability of the anodes was evaluated under wet H₂ and CO₂ atmosphere at 700 °C. The electrical properties of the Ni-BCY10 pellets were evaluated using electrochemical impedance spectroscopy measurements. The Ni-BCY10 cermet electrodes showed large electronic conductivity, demonstrating percolation through the Ni particles, and low area specific resistance at the BCY10 interface. These characteristics make the cermet suitable for application in BCY-based protonic fuel cells. The developed chemical route offers a simple and low-cost procedure to obtain promising high performance anodes.