(π)C—H···S, (allyl)C—H···C(π) and π···π intermolecular interactions: synthesis, characterization, and crystal structure of 2,2′-bipyridine bis(diallyldithiocarbamato)zinc(II)

A mixed-ligand Zn(II) complex formulated as [Zn(aldtc)₂(bipy)] (aldtc=diallyldithiocarbamate; bipy=2,2′-bipyridine) was synthesized and characterized by IR, ¹H and ¹³C NMR spectral measurements and X-ray crystallography. The crystal structure of this complex indicates that Zn has a distorted octahedral geometry. The Zn—N distances are invariant (2.168(2) Å), while those of the Zn—S are slightly different (2.5408(9) and 2.5440(9) Å). The N—Zn—N, S—Zn—S and N—Zn—S bond angles are in the range 75.35(13)–99.75(7)°, 70.48(3)–161.02(5)° and 95.26(7)–160.32(7)°, respectively. The crystal packing of the complex shows different motifs of supramolecularity resulting from both hydrophilic ((π)C—H···S) and hydrophobic ((allyl)C—H···C(π)) intermolecular interactions. These interactions result in a chain arrangement of molecules along crystallographic c axis and the chains are further connected via π···π stacking along with ((π)C—H···S along b axis leading to an overall crystal packing that can be regarded as layers of complexes along bc plane, which are held together through nonconventional hydrogen bonding and π···π stacking.     

Fullerene‐Catalyzed Reduction of Azo Derivatives in Water under UV Irradiation

Metal‐free fullerene (C₆₀) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH₄. Use of NaBH₄ by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C₆₀ catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N?N bond. UV irradiation increases the ability of C₆₀ to interact with electron‐donor moieties in azo dyes.     

Hippocampal metabolomics using ultrahigh-resolution mass spectrometry reveals neuroinflammation from Alzheimer’s disease in CRND8 mice

In the wake of genomics, metabolomics characterizes the small molecular metabolites revealing the phenotypes induced by gene mutants. To address the metabolic signatures in the hippocampus of the amyloid-beta (Aβ) peptides produced in transgenic (Tg) CRND8 mice, high-field ion cyclotron resonance–Fourier transform mass spectrometry supported by LC-LTQ-Orbitrap was introduced to profile the extracted metabolites. More than 10,000 ions were detected in the mass profile for each sample. Subsequently, peak alignment and the 80 % rule followed by feature selection based on T score computation were performed. The putative identification was also conducted using the highly accurate masses with isotopic distribution by interfacing the MassTRIX database as well as MS/MS fragmentation generated in the LTQ-Orbitrap after chromatographic separation. Consequently, 58 differentiating masses were tentatively identified while up to 44 differentiating elemental compositions could not be biologically annotated in the databases. Nonetheless, of the putatively annotated masses, eicosanoids in arachidonic acid metabolism, fatty acid beta-oxidation disorders as well as disturbed glucose metabolism were highlighted as metabolic traits of Aβ toxicity in Tg CRND8 mice. Furthermore, a web-based bioinformatic tool was used for simulation of the metabolic pathways. As a result of the obtained metabolic signatures, the arachidonic acid metabolism dominates the metabolic perturbation in hippocampal tissues of Tg CRND8 mice compared to non-Tg littermates, indicating that Aβ toxicity functions neuroinflammation in hippocampal tissue and new theranostic opportunities might be offered by characterization of altered arachidonic acid metabolism for Alzheimer’s disease.      

Regularization of weights

We show how to approximate a given weight function in the class by weights that are bounded above by multiples of their infima in such a way that the constant is not increased. As an application, we show that the precise range of for which a given weight is in cannot be determined by extrapolating the constants.

     

Efficient shooting method for solving two point boundary value problems

We present an efficient shooting method for solving two point boundary value problems. The Adomian decomposition method will be utilized to obtain a series solution of the initial value problems involved. Numerical examples and comparison of the work of others will also be done.     

Reduced-order representation of stratified wakes by proper orthogonal decomposition utilizing translational symmetry

Journal of Visualization - Visualizations of reduced-order representations of stratified wakes of Reynolds number $$Re \in \{5,25,100\}\times 10^3$$ are presented at a fixed internal Froude number....     

Crystal supramolecularity in 2,2′-iminodipyridinium tetrahalometallate(II) salts: Supramolecular motifs that control tetrahedral halometallate solid state structures

N⁺–H$?$Br–M and (π)C–H$?$Br–M hydrogen bond synthons have been exploited in the crystallization of a series of 2,2′-iminodipyridinium(2+) dication (hereafter 2,2′-imdipyH₂), (C₁₀H₁₁N₃)[MX₄] salts (M = Co and Hg; X = Cl and Br) and 2,2′-iminodipyridinium(1+) cation (hereafter 2,2′-imdipyH), (C₁₀H₁₀N₃)₂[MX₄] salts (M = Co, Hg; X = Cl and Br). Intermolecular interactions and crystal supramolecularity adopted in these structures were analyzed and compared with reported similar structures, (C₁₀H₁₁N₃)[CuCl₄] and (C₁₀H₁₀N₃)₂[CoCl₄]. In these salts only one structural form for the halometallate species is observed namely mononuclear tetrahedral. The crystal supramolecularity in the (2,2′-imdipyH₂)[MX₄] series corresponds to three distinct structural motifs: Parallel ribbons of infinitely connected cyclic dimers of two dications and two anions found in the isomorphous salts of [CoCl₄]^2? and [CuCl₄]^2?; and cyclic dimer hearing-bone packing motif found in the isomorphous dication salts of [CoBr₄]^2? and [HgBr₄]^2?. Infinitely helical layers based on alternating $?$anion$?$two stacked cations $?$anion$?$ two stacked cations$?$ are found in the isomorphous salts of (2,2′-imdipyH)₂[CoCl₄] and (2,2′-imdipyH)₂[HgBr₄].     

Kinetics and mechanism of benzoin oxidation using iron(III) in the presence of ferrozine or 2,2'‐bipyridine in acidic medium

Kinetics and mechanism of oxidation of benzoin (H₂B) by ferrozine (Fz) or 2,2'‐bipyridine (bipy) have been carried out in aqueous HNO₃ medium. The rate shows first‐order dependence on [H₂B] and [Fe³⁺] and inverse second‐order dependence on [H⁺]. The rate of reaction increased with increase in the ligand concentration. The increase in dielectric constant will increase the rate, while increase in [HNO₃] decreased it. Substituent and temperature effects on the rates have been investigated. The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 444–449, 2005