Caulerpin

The crystal structure of caulerpin (di­methyl 6,13‐di­hydro­dibenzo­[b,i]­phenazine‐5,12‐di­carboxyl­ate, C₂₄H₁₈N₂O₄), an indole alkaloid, reported in space group Cc with an acute β angle, has been redetermined in the correct space group, C2/c. The mol­ecule has twofold crystallographic symmetry and is composed of two essentially planar indole groups fused to an eight‐membered cyclo­octatetraene ring which adopts a boat conformation. The molecular dimensions are normal. The structure is stabilized by intermolecular and intramolecular interactions involving the indole N—H atom and carbonyl O atom [N?O 3.211 (4) and 2.836 (4) Å].     

Melt spinning and laser‐heated drawing of a new semiaromatic polyamide,PA9‐T fiber

Fibers of PA9‐T, a new semiaromatic polyamide containing a long aliphatic chain, were prepared by melt spinning. As‐spun fibers were subsequently drawn with a CO₂ laser‐heated drawing system at different draw ratios and various drawing velocities. On‐line observations of drawing points deciphered two drawing states; namely, flow drawing and neck drawing, over the entire range of drawing. Drawing stress revealed that flow drawing is induced by slight drawing stress under a low draw ratio up to 3, and neck drawing is induced by relatively high drawing stress under a higher draw ratio. The effect of drawing stress and drawing velocity on the development of the structure and properties has been characterized through analysis of birefringence, density, WAXD patterns, and tensile, thermal, and dynamic viscoelastic properties. For the neck‐drawn fibers, almost proportional enhancements of crystallinity and molecular orientation with drawing stress were observed. The flow‐drawn fibers have an essentially amorphous structure, and birefringence and density do not always have a linear relation with properties. The fibers drawn at high drawing speed exhibit improved fiber structure and superior mechanical properties. The maximum tensile strength and Young's modulus of PA9‐T drawn fibers were found to be 652 MPa and 5.3 GPa, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 433–444, 2004     

Novel Visible-Light-Driven Photocatalyst Co<Subscript>3</Subscript>O<Subscript>4</Subscript>/FeWO<Subscript>4</Subscript> for Efficient Decomposition of Organic Pollutants

A highly efficient and visible light (λ ≥ 420 nm) responsive composite photocatalyst, Co₃O₄/FeWO₄ was prepared by simple impregnation method. The heterojunction semiconductors Co₃O₄/FeWO₄ demonstrated notably high photocatalytic activity over a wide range of composition than the individual component Co₃O₄ or FeWO₄ for the complete degradation of 1,4-dichlorobenzene (DCB) in aqueous phase under visible light irradiation. The photocatalytic activity of composite was optimized at 1/99 Co₃O₄/FeWO₄ composition. After 2 h of visible light irradiation 51% decomposition of 1,4-dichlorobenzene (DCB) was observed utilizing 1/99 Co₃O₄/FeWO₄ photocatalyst while the end members demonstrated a negligible degradation under the same experimental condition. The valence band (VB) and conduction band (CB) of Co₃O₄ is located above the VB and CB of FeWO₄, respectively. Both the semiconductors Co₃O₄ and FeWO₄ exhibit strong absorption over the wide range of visible light. The obviously enhanced photocatalytic performance of Co₃O₄/FeWO₄ composite has been discussed on the hole (h⁺) as well as electron (e^?) transfer mechanism between the VB and CB of individual semiconductors.     

Synthesis,characterization, and antimicrobial studies of some palladium complexes with an octamethyl tetraazacyclotetradecadiene ligand and isomers of its reduced form

Biologically important tetraaza-macrocyclic ligand 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene dihydroperchlorate, Me₈[14]diene·2HClO₄ (L₁·2HClO₄) was synthesized by the condensation of 1,2-diaminopropane with acetone in presence of quantitative amount of HClO₄ and three isomeric ligands designated as L_A, L_B and L_C were separated by the reduction of L₁·2HClO₄ with NaBH₄ and fractional crystallization from xylene. The nitrato, nitro, bromido, and iodido complexes of palladium with diene ligand L₁ were prepared by the interaction of L₁·2HClO₄ with K₂[Pd(NO₃)₄], K₂[Pd(NO₂)₄], K₂[PdBr₄], and K₂[PdI₄] (prepared by the reactions with PdCl₂ with KNO₃, KNO₂, KBr, and KI, respectively), respectively. The bromide and iodido complexes of L_A were prepared by the axial substitution reactions with [PdL_ACl₂]Cl₂. By contrast, similar complexes of other isomeric ligands L_B and L_C were prepared by axial addition reactions of [PdL^?][PdCl₄] (L′?=?L_B or L_C) with KBr and KI, respectively. The complexes were characterized on the basis of elemental analysis: IR, ¹H-NMR, UV–Vis spectroscopic analysis, and magnetic and molar conductivity data. The antifungal and antibacterial activities of these compounds have been studied against some phyto-pathogenic fungi and bacteria.     

The metal-to-ligand charge-transfer luminescences of ruthenium(II)-polypyridine-tetraam(m)ine complexes. Support for the interconvertibility of optical and thermal (kinetic) Franck-Condon parameters

This is the first report of the metal-to-ligand charge-transfer (MLCT) emission spectra of the bis-ethylenediamine- and tetraammine-bipyridineruthenium(II) complexes. The emission maxima occur at 800 and 840 nm, respectively, at 77 K in DMSO/H(2)O glasses. The MLCT excited states of these complexes have short lifetimes (less than 50 ns), and as a consequence, the emission intensities are very small. The energies of the emission maxima are very close to those expected on the basis of the difference in reduction potentials of the metal and ligand (DeltaE(1/2)) and the values of the reorganizational free energies (chi(r)) of the vertical transitions estimated from the electron-transfer self-exchange reactions of the complexes (hnu(max)(em) congruent with FDeltaE(1/2) - chi(r), where F is Faraday's constant). The low energy of the emissions is in large part a consequence of the substantial contributions of the reorganizational free energies.     

Absolute configuration of 1β,10β-epoxydesacetoxymatricarin isolated from Carthamus oxycantha by means of TDDFT CD calculations

The absolute configuration of 1β,10β-epoxydesacetoxymatricarin 1, a sesquiterpenoid isolated from Carthamus oxycantha, was established by TDDFT CD calculations in combination with single crystal X-ray analysis. Since the solid-state CD spectrum shows contributions from intermolecular interactions in the crystal, 1 represents a test case for our solid-state CD/TDDFT approach.     

Simulation of flow‐flexible body interactions with large deformation

A modified front‐tracking method was proposed for the simulation of fluid‐flexible body interactions with large deformations. A large deformable body was modeled by restructuring the body using a grid adaptation. Discontinuities in the viscosity at the fluid‐structure interface were incorporated by distributing the viscosity across the interface using an indicator function. A viscosity gradient field was created near the interface, and a smooth transition occurred between the structure and the fluid. The fluid motion was defined on the Eulerian domain and was solved using the fractional step method on a staggered Cartesian grid system. The solid motion was described by Lagrangian variables and was solved by the finite element method on an unstructured triangular mesh. The fluid motion and the structure motion were independently solved, and their interaction force was calculated using a feedback law. The interaction force was the restoring force of a stiff spring with damping, and spread from the Lagrangian coordinates to the Eulerian grid by a smoothed approximation of the Dirac delta function. In the numerical simulations, we validated the effect of the grid adaptation on the solid solver using a vibrating circular ring. The effects of the viscosity gradient field were verified by solving the deformation of a circular disk in a linear shear flow, including an elastic ring moving through a channel with constriction, deformation of a suspended catenary, and a swimming jellyfish. A comparison of the numerical results with the theoretical solutions was presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Current progresses and trends in carbon nanomaterials-based electrochemical and electrochemiluminescence biosensors

The enormous potential of biosensors in medical diagnostics has motivated scientists to develop newer innovative tools and advance biosensing technologies. The use of cell, organelles, nucleotides, aptamers, antibodies, affibodies, proteins, peptides, molecules, and printed polymers, merged with nanotechnology, offers excellent tools to prepare highly sensitive and advanced biosensors. Therefore, the current decade has witnessed a rapid surge in the fabrication of different nanomaterial-based biosensors. Among them, carbon nanomaterials (CNMs) have emerged highly attractive in the fabrication of both electrochemical and electrochemiluminescence (ECL) biosensors. On one hand, CNMs bear prominent electrical conductivity, large surface area to immobilize adequate amount of biomolecules, an enhanced loading capacity, improved biocompatibility, and active site for electrochemical reaction. Additionally, CNMs could be chemically modified for the covalent coupling with the biomolecules. On the other hand, both electrochemical and ECL biosensors allow for cost-effective, rapid, and real-time detection with excellent sensitivity and selectivity, with the capability of integrating different biomolecules and CNMs on the same chip. However, currently there is not a single review, which includes CNM-based electrochemical and ECL biosensors' current progress and trends. Therefore, this review intends to survey the current progress and future trends in CNM-based electrochemical and ECL biosensors.     

Synthesis,characterization, thermal and luminescent properties of thiophenol-functionalized platinum(II) bis(acetylide) complexes

Transition Metal Chemistry - Two thiophenol-functionalized trans-platinum(II) bis(acetylide) complexes, having one thiophenol moiety in each alkenyl backbone with general formula...