Design,Synthesis, and Biological Activity of New Bis-1,2,3-triazole Derivatives Bearing Thiophene-Chalcone Moiety

Russian Journal of General Chemistry - A series of novel 1,4-substituted bis-aralkyl and aryl 1,2,3-triazoles bearing thiophene chalcones are synthesized via the Claisen condensation of bis...     

Electrodeposited three dimensional tin nano wire anode for thin film Li-Ion micro batteries

The tin wire grown over anodic aluminium oxide template is used as anode for Li ion batteries. This work entails porous template formation through double step electrochemical oxidation method optimized by design of experiment and Tafel polarization. The X-ray diffraction results of different anodized specimens show amorphous alumina layer formation. The pores in alumina matrix and the filamentous outward projection of Sn wires are observed from micrographs. The initial discharge capacity of Sn wire and Sn planar thin film is observed to be around 850 and 531 mA h/g respectively. The 50th cycle capacity of Sn wire is observed to be around 494 mA h/g which is very high when compared to theoretical capacity of graphite anodes.     

Hybrid peptides: expanding the beta turn in peptide hairpins by the insertion of beta-, gamma-, and delta-residues

The beta turn segment in designed peptide hairpins has been expanded by the insertion of beta-, gamma- and delta-amino acids at the i+2 position. The model octapeptides Boc-Leu-Phe-Val-DPro-Ac6c-Leu-Phe-Val-OMe (1), Boc-Leu-Phe-Val-DPro-beta3-Ac6c-Leu-Phe-Val-OMe (2), and Boc-Leu-Phe-Val-DPro-Gpn-Leu-Phe-Val-OMe (3) have been shown to adopt beta hairpin conformations in methanol by the observation of key diagnostic nuclear Overhauser effects. Boc-Leu-Val-Val-DPro-delta-Ava-Leu-Val-Val-OMe (4) adopts a beta hairpin conformation in crystals; this is stabilized by three cross-strand hydrogen bonds as demonstrated by X-ray diffraction. The canonical C10 turn in an alpha-alpha segment is expanded to C11, C12, and C13 turns in alpha-beta, alpha-gamma, and alpha-delta segments, respectively. The crystal structures of Piv-LPro-beta3-Ac6c-NHMe (5) and Boc-Ac6c-Gpn-Ac6c-OMe (6) reveal intramolecularly hydrogen-bonded C11 and C12 conformations, respectively. Computer modeling of octapeptide sequences that contain centrally positioned hybrid-turn segments, by using turn parameters derived from the structures of peptides 5 and 6, establishes the stereochemical acceptability of the beta hairpins in the cases of peptides 2 and 3. Accommodation of omega-amino acids into the turn segments is achieved by the adoption of gauche conformations around the backbone C--C bonds.     

Triazabicyclodecene: an effective isotope exchange catalyst in CDCl(3)

We describe the first effective H/D exchange reaction with acidic substrates in CDCl(3) at room temperature. The particularly mild reaction conditions involved (solvent, base, and temperature) allow the chemoselective deuteration of ketones over esters. An NMR study was conducted with the aim of rationalizing the results obtained in the presence of TBD as catalyst.     

Microbial metabolism. Part 7 : Curcumin

Microbial metabolism of the cancer chemopreventive agent, curcumin [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione] (1) with Pichia anomala (ATCC 20170) yielded four major metabolites, 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptan-3-one (2), 5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)heptan-3-one (3), 1,7-bis(4-hydroxy-3-methoxyphenyl)heptan-3,5-diol (4), 5-hydroxy-1,7-bis(4-hydroxyphenyl)heptane-3-one (5) and two minor products, 1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)heptane-3,5-diol (6) and 1,7-bis(4-hydroxyphenyl)heptane-3,5-diol (7). The structures of compounds 2-5 were established on the basis of spectroscopic data. Compounds 6 and 7 were assigned tentative structures.     

Kinetics of oxidation of indigo carmine by N-sodio-N-bromotoluenesulfonamide in acidic buffer medium

The kinetics of oxidation of indigo carmine (IC) by N-sodio-N-bromotoluenesulfonamide or bromamine-T (BAT) in pH 5 buffer medium has been investigated at 30°C using spectrophotometry at 610 nm. The reaction rate shows dependencies of first-order on [IC]₀ second-order on [BAT]₀, fractional order on [H⁺], and inverse first-order on [ρ-toluenesulfonamide]. The addition of chloride and bromide ions, and the variation of ionic strength of the medium have no influence on the reaction rate. There is a negative effect of the dielectric constant of the solvent. Activation parameters have been calculated. A single-pathway mechanism for the reaction, consistent with the kinetic data, has been proposed. © John Wiley & Sons, Inc. Int J Chem Kinet 29: 453–459, 1997     

Renewable resources based polymers: Synthesis and characterization of 2,5-diformylfuran-urea resin

Condensation of renewable resources based monomer 2,5-diformylfuran (DFF) and urea at 110 °C by melting a solid mixture gives a crystalline polymer resin in 90% yield. This resin was characterized by elemental analysis, ¹H, ¹³C and ¹H-¹H COSY NMR, IR, UV, TGA and DTA. The structural unit of this new material consists of one DFF molecule condensed with two urea molecules at the aldehyde group of DFF. A homologous resin was prepared by using 5,5′-oxydimethylenebis(2-furaldehyde) and urea in 84% yield via a similar procedure and characterized as well.     

Synthesis and Crystal Structure Studies of Novel Bioactive Heterocycle: 7-Chloro-5-Cyclopropyl-9-Methyl-10-(2-Piperidin-1-yl-Ethyl)-5,10-Dihydro-4,5,6,10-Tetraaza-Dibenzo[a,d] Cyclohepten-11-One

Abstract  The compound, 7-chloro-5-cyclopropyl-9-methyl-10-(2-piperidin-1-yl-ethyl)-5,10-dihydro-4,5,6,10-tetraaza-dibenzo[a, d] cyclohepten-11-one, C₂₂H₂₆N₅ClO, crystallizes in the triclinic space group Pī with cell parameters a = 8.918(7) ?, b = 9.297(7) ?, c = 14.184(8) ?, V = 1095.98(1) ?³ and Z = 2. The final residual factor R ₁ = 0.0451. The structure exhibits intermolecular hydrogen bonds. The 2-piperidin-1-yl-ethyl ring adopts a chair conformation. The starting material used to synthesize the title compound is the intermediate compound of well known anti-HIV drug Nevirapine hence the title compound is having biological importance and hence this crystal structure will helps to structural characterization of the molecule and also for the molecular modeling it will helps for biological study. Graphical Abstract  The title compound 7-chloro-5-cyclopropyl-9-methyl-10-(2-piperidin-1-yl-ethyl)-5,10-dihydro-4,5,6,10-tetraaza-dibenzo[a, d] cyclohepten-11-one was synthesized by condensation of 7-chloro-5-cyclopropyl-9-methyl-5,10-dihydro-4,5,6,10-tetraaza-dibenzo[a, d] cyclohepten-11-one with 1-(2-chloro-ethyl)-piperidine hydrochloride in presence of anhydrous powdered potassium carbonate as base using N,N-dimethyl formamide as solvent and its crystal structure determined. The title compound derived from bioactive molecule and it is also having biological importance hence this crystal structure will helps for the structural characterization and the biological study of the novel molecule.      

Structural Conformation of a Novel 1-Benzhydrylpiperazine Derivative: 1-Benzhydryl-4-(toluene-4-sulfonyl)-piperazine

Abstract  The title compound 1-benzhydryl-4-(toluene-4-sulfonyl)-piperazine was synthesized and the structure was investigated by X-ray crystallography. The title compound, C₂₄H₂₆N₂O₂S crystallizes in the monoclinic crystal class in the space group P2₁/c with cell parameters a = 13.5800(10) ?, b = 8.9630(7) ?, c = 18.9040(10) ?, β = 106.851(3)°, Z = 4 and V = 2202.1(3) ?³. The structure has been solved by direct methods and refined to R ₁ = 0.0468 for 3174 observed reflections I > 2σ(I). The structure reveals that the piperazine ring is in a chair conformation. The geometry around the S atom is a distorted tetrahedron. Graphical Abstract  The title compound 1-benzhydryl-4-(toluene-4-sulfonyl)-piperazine was synthesized and the structure was investigated by X-ray crystallography. The title compound, C₂₄H₂₆N₂O₂S crystallizes in the monoclinic crystal class in the space group P2₁/c with cell parameters a = 13.5800(10) ?, b = 8.9630(7) ?, c = 18.9040(10) ?, β = 106.851(3)°, Z = 4 and V = 2202.1(3) ?³. The structure has been solved by direct methods and refined to R ₁ = 0.0468 for 3174 observed reflections I > 2σ(I). The structure reveals that the piperazine ring is in a chair conformation. The geometry around the S atom is a distorted tetrahedron.

Optimal buffer size for a stochastic processing network in heavy traffic

We consider a one-dimensional stochastic control problem that arises from queueing network applications. The state process corresponding to the queue-length process is given by a stochastic differential equation which reflects at the origin. The controller can choose the drift coefficient which represents the service rate and the buffer size b>0. When the queue length reaches b, the new customers are rejected and this incurs a penalty. There are three types of costs involved: A “control cost” related to the dynamically controlled service rate, a “congestion cost” which depends on the queue length and a “rejection penalty” for the rejection of the customers. We consider the problem of minimizing long-term average cost, which is also known as the ergodic cost criterion. We obtain an optimal drift rate (i.e. an optimal service rate) as well as the optimal buffer size b ^*>0. When the buffer size b>0 is fixed and where there is no congestion cost, this problem is similar to the work in Ata, Harrison and Shepp (Ann. Appl. Probab. 15, 1145–1160, 2005). Our method is quite different from that of (Ata, Harrison and Shepp (Ann. Appl. Probab. 15, 1145–1160, 2005)). To obtain a solution to the corresponding Hamilton–Jacobi–Bellman (HJB) equation, we analyze a family of ordinary differential equations. We make use of some specific characteristics of this family of solutions to obtain the optimal buffer size b ^*>0. A.P. Weerasinghe’s research supported by US Army Research Office grant W911NF0510032.