Synthesis,X-Ray Crystal Structure and Spectroscopic Properties of 1,2,3,4-Tetrahydro-2-(thenyl)-3-(<Emphasis Type="Italic">N</Emphasis>-thenylidine)-4-oxoquinazoline

Abstract  

The Schiff base formed between anthraniloyl hydrazide and thiophen-2-aldehyde is synthesized. Reaction of this Schiff base with VOSO₄ in methanol at room temperature does not yield the expected vanadium complex; instead, the Schiff base is transformed to 1,2,3,4-tetrahydro-2-(thenyl)-3-(N-thenylidine)-4-oxoquinazoline, which has been characterized by elemental analyses and by LC–MS, i.r., n.m.r. and electronic spectroscopies. The X-ray crystal structure of the quinazoline product is reported. The compound crystallizes with monoclinic (P2₁/n) space group, and the cell parameters are: a = 5.9442(7) ?, b = 13.6357(15) ?, c = 19.455(2) ?, β = 90.499(2)°. The oxo-quinazoline product is found to be luminescent when excited at its lowest energy transition.     

The lowest order relativistic corrections for the hydrogen molecule

We have calculated the lowest order relativistic corrections for the X ¹Σ, B¹Σ, a³Σ, b³Σ, I¹Π_g, C¹Π_u, i³Π_g, c³Π_u, J¹Δ_g, and j³Δ_g states of the hydrogen molecule using variational Monte Carlo methods and compact, explicitly correlated trial wavefunctions. Our values are in good agreement with earlier calculations on the X¹Σ and B¹Σ states. For the other states, our work provides the first estimate of these properties. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Spontaneous formation of vesicles by sodium 2-dodecylnicotinate in water

The surface activity and aggregation behavior of a synthesized nicotinic acid based anionic surfactant, sodium 2-dodecylnicotinate, were studied in aqueous solution. The self-assembly formation was investigated by use of a number of techniques, including surface tension and conductivity measurements, fluorescence spectroscopy, dynamic light scattering measurement, gel permeation chromatography, and microscopy. The amphiphile exhibits two breaks in the surface tension vs concentration plot, indicating stepwise aggregate formation and thus producing two values of the aggregation concentration. Stepwise aggregation of the amphiphile was further confirmed by steady-state fluorescence spectroscopy using pyrene as a probe molecule, and also the micropolarity of the aggregates was determined. The rigidity of the microenvironment was estimated by determining steady-state fluorescence anisotropy using 1,6-diphenyl-1,3,5-hexatriene as a fluorescence probe molecule. The average hydrodynamic radius and size distribution of the aggregate suggest formation of larger aggregates in aqueous solution. The formation of vesicles in water was established by conductivity measurement and a dye entrapment experiment. The entrapment of a small solute and the release capability have also been examined to demonstrate these bilayers form enclosed vesicles. Transmission electron micrographs revealed the existence of closed vesicles and closed tubules in aqueous solution. Therefore, for the first time, it has been observed that this simple single-chain nicotinic acid based amphiphile spontaneously assembles to vesicles in aqueous solution.     

Response of Cellulase Activity in pH-Controlled Cultures of the Filamentous Fungus <Emphasis Type="Italic">Acremonium cellulolyticus</Emphasis>

Cellulase production was investigated in pH-controlled cultures of Acremonium cellulolyticus. The response to culture pH was investigated for three cellulolytic enzymes, carbomethyl cellulase (CMCase), avicelase, and β-glucosidase. Avicelase and β-glucosidase showed similar profiles, with maximum activity in cultures at pH 5.5–6. The CMCase activity was highest in a pH 4 culture. At an acidic pH, the ratios of CMCase and avicelase activity to cellulase activity defined by filter paper unit were high, but at a neutral pH, the β-glucosidase ratio was high. The pH 6.0 culture showed the highest cellulase activity within the range of pH 3.5–6.5 cultures. The saccharification activity from A. cellulolyticus was compared to those of the cellulolytic enzymes from other species. The A. cellulolyticus culture broth had a saccharification yield comparable to those of the Trichoderma enzymes GC220 and Cellulosin T2, under conditions with the same cellulase activity. The saccharification yields from Solka floc, Avicel, and waste paper, measured as the percent of released reducing sugar to dried substrate, were greater than 80% after 96 h of reaction. The yields were 16% from carboxymethylcellulose and 26% from wood chip refiner. Thus, the A. cellulolyticus enzymes were suitable for converting cellulolytic biomass to reducing sugars for biomass ethanol production. This study is a step toward the establishment of an efficient system to reutilize cellulolytic biomass.     

Ab initio study on one-way photoisomerization of the maleic acid and fumaric acid anion radical system as a model system of their esters

Potential energy surfaces (PESs) of the maleic acid anion radical (MA-*: cis isomer)/fumaric acid anion radical (FA-*: trans isomer) system as a model system of their esters have been studied in detail using CASSCF method. The results suggest the following: The photoisomerization is initiated with the H-C-C-H dihedral angle distortion [hydrogen out of plain (HOOP) motion] on the D1 PES. The C-C-C-C dihedral angle distortion occurs on the D0 PES after the deactivation from D1 to D0. A large fraction of the net motion along the isomerization coordinate occurs on the D0 PES. The D0 state is responsible for the one-way nature of the photoisomerization.     

Establishing a protocol for trace element determinations in serum samples from healthy elderly population in São Paulo city, SP, Brazil

Summary In this study a protocol for blood serum analysis was defined and the concentrations for Br, Ca, Cl, Fe, Na, Rb, Se and Zn were obtained by instrumental neutron activation analysis. Blood samples were collected from healthy elderly volunteers who were selected based on the SENIEUR protocol. Contamination of blood by the collection procedure was also evaluated and found negligible. The serum was separated by centrifugation, then freeze-dried and analyzed. Most of results obtained were within the acceptable value ranges used by physicians for normal population. The certified reference material, NIST SRM 1566b Oyster Tissue was analyzed for quality control.     

An approach to one‐dimensional conductive polymer composites

A substantial approach to one‐dimensional (1D) electrically conductive composites was proposed which was based on the thermodynamic analysis of electric‐field‐induced particle alignment in a nonpolar thermoplastic polymer matrix. The process condition window was based on the real‐time exploration of dynamic percolation under different electric fields with carbon black (CB)‐filled polyethylene as a model. The CB content was the main factor of the process condition. Its upper limit was set as the critical percolation concentration at the thermodynamic equilibrium state without an electric field to eliminate the possibility of conductive network formation perpendicular to the electric‐field direction, whereas its lower limit the critical percolation concentration at the thermodynamic equilibrium state under a critical electric field (E*). A composite with CB content in this window, isothermally treated in an electric field not less than E*, showed conductivity in the electric‐field direction about 10⁵ times larger than that in the perpendicular direction. A 1D cluster structure in the direction of the electric filed was confirmed with scanning electron microscopy morphology observations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 184–189, 2005     

p-tert-Butylcalix[8]arene catalysed synthesis of 3,5-dinitrothiophene scaffolds: antiproliferative effect of some representative compounds on selective anticancer cell lines

A new efficient protocol for the synthesis of 3,5-dinitrothiophene scaffolds was developed by using simple p-tert-butylcalix[8]arene in aqueous medium. Biological activities of some representative compounds were also studied to inhibit the cell growth on selective anticancer cell lines.     

Protonation Switching to the Least‐Basic Heteroatom of Carbamate through Cationic Hydrogen Bonding Promotes the Formation of Isocyanate Cations

We found that phenethylcarbamates that bear ortho‐salicylate as an ether group (carbamoyl salicylates) dramatically accelerate O?C bond dissociation in strong acid to facilitate generation of isocyanate cation (N‐protonated isocyanates), which undergo subsequent intramolecular aromatic electrophilic cyclization to give dihydroisoquinolones. To generate isocyanate cations from carbamates in acidic media as electrophiles for aromatic substitution, protonation at the ether oxygen, the least basic heteroatom, is essential to promote C?O bond cleavage. However, the carbonyl oxygen of carbamates, the most basic site, is protonated exclusively in strong acids. We found that the protonation site can be shifted to an alternative basic atom by linking methyl salicylate to the ether oxygen of carbamate. The methyl ester oxygen ortho to the phenolic (ether) oxygen of salicylate is as basic as the carbamate carbonyl oxygen, and we found that monoprotonation at the methyl ester oxygen in strong acid resulted in the formation of an intramolecular cationic hydrogen bond (>C?O⁺?H???O<) with the phenolic ether oxygen. This facilitates O?C bond dissociation of phenethylcarbamates, thereby promoting isocyanate cation formation. In contrast, superacid‐mediated diprotonation at the methyl ester oxygen of the salicylate and the carbonyl oxygen of the carbamate afforded a rather stable dication, which did not readily undergo C?O bond dissociation. This is an unprecedented and unknown case in which the monocation has greater reactivity than the dication.     

Total dual integrality of the linear complementarity problem

Annals of Operations Research - In this paper, we introduce total dual integrality of the linear complementarity problem (LCP) by analogy with the linear programming problem. The main idea of...