Efficient sonochemical synthesis of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides

An ultrasound-assisted preparation of a series of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides that proceeds via the efficient reaction of chalcones with aminoguanidine hydrochloride under clean conditions is described.     

Bell polynomials and generalized Blissard problems

We introduce two possible generalizations of the classical Blissard problem and we show how to solve them by using the second order and multi-dimensional Bell polynomials, whose most important properties are recalled.     

A rheological method for selecting nano-kaolin powder as filler in SBR rubber

This paper shows that the stiffness of styrene-butadiene solid rubber with added kaolin powder is related to the yield stress of kaolin dispersion in liquid polybutadiene rubber up to the percolation threshold.For five kinds of kaolin powder,the value of τ spans the range of 100-430Pa,while the corresponding compressive elastic constant of SBR varies from 12 to 21MPa.A relationship between τ° and ΔE*i/E*R is proposed.Critical examination of these data infers that kaolin powder dispersed in solid rubber matrix acts as an additive which decreases the random movement of the polybutadiene chains.Consequently,dispersions of nano-particles in liquid and in solid SBR are considered to be related,thus leading to a rheological method for selecting nano-particles as fillers in solid SBR.     

Ionic silica based hybrid material containing the pyridinium group used as an adsorbent for textile dye

The present study reports the development of an ionic silica based hybrid material containing the cationic pyridinium group, which was employed for the removal of the Reactive Red 194 textile dye from aqueous solution. Three hybrid material samples were prepared with planned textural and chemical properties, varying the inorganic precursor molar percentage in the sol-gel synthesis. The obtained samples were defined as Py/Si-90, Py/Si-92 and Py/Si-94, where the number specifies the inorganic molar percentage. The hybrid samples were characterized by elemental, infrared, (13)C and (29)Si NMR, N(2) adsorption-desorption isotherms and thermogravimetric analyses. The dye-removing ability of these adsorbents was determined by the batch contact adsorption procedure. Effects such as pH value and adsorbent dosage on the adsorption capacities were studied. Four kinetic models were applied. The adsorption was best fitted to Avrami fractional-order kinetic model for the three hybrid material samples. The kinetic data were also adjusted to an intra-particle diffusion model resulting three linear regions, indicating that the adsorption kinetics follows multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich and Liu isotherm models. The maximum adsorption capacities were 165.4, 190.3 and 195.9 mg g(-1) for Py/Si-90, Py/Si-92 and Py/Si-94, respectively. Simulated dye-house effluents were used to check the applicability of the proposed adsorbents for effluent treatment. Dye loaded adsorbents were regenerated (>98.2%) by using 0.4 mol L(-1) of NaOH solution as an eluent.     

Energy transfer from poly(vinyl carbazole) to a fluorene-vinylene copolymer in solution and in the solid state

This article reports a comparative study of the energy transfer processes in solution and the solid state from poly(vinyl carbazole; the donor) to dimethylphenyl-terminated poly[(9,9-dioctylfluorenyl-2,7-divinylene-fluorene)-co-alt-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (the acceptor). The results in solutions suggest that a decrease of the donor emission intensity with an increasing acceptor concentration is more closely related to the trivial energy transfer process, indicating that the donor and acceptor chains are not in close contact during the lifetime of the donor excited state. This conclusion was reached using the amplitude-averaged lifetime of the donor, which is practically independent of the acceptor concentration. In the solid state, the polymer blends showed a decrease in the donor emission with an increasing acceptor concentration, and a decrease in the donor lifetime was also observed. Thus, in the solid state, changes in morphology interfere with the nonradiative resonant energy transfer process, but influence on the trivial process cannot be completely neglected. The lifetime does not follow a continuous decrease with the PFO-MEHPV concentration like the emission intensity does. The changes in the lifetime values occur over the same concentration range as do the changes of morphology, as shown by the scanning electron micrographs.     

Synthesis of novel anthracene derivatives of isoxazolino-carbocyclic nucleoside analogues

The synthesis of isoxazolino-carbocyclic nor-nucleosides incorporating an anthracene moiety was properly tuned through nitrosocarbonyl intermediates chemistry, and a variety of analogues were attained starting from stereodefined heterocyclic aminols through the linear construction of purine heterocyclic rings. The synthesis hinges on the exo selective 1,3-dipolar cycloaddition of the stable anthracenenitrile oxide to the N-benzoyl-2,3-oxazanorborn-5-ene and simple elaborations of the cycloadducts. A selection of nucleoside derivatives were initially tested for their inhibitory activity against a variety of viruses, including Hepatitis B and C, Human Papilloma virus as well as Influenza viruses of type A and B. Modest anti-viral activities were observed in Hepatitis assays while the activities in the cases of Influenza viruses were almost negligible. Good anti-viral activity was found for compound 11bC with no cellular toxicity at the dose tested in the case of Human Papilloma virus.     

Structure Determination of 8-Benzyl-5-phenyl-3-oxa-4,8-diaza-tricyclo[5.2.1.02,6]dec-4-ene and 1-(9-Ethoxy-5-phenyl-3-oxa-4,8-diaza-tricyclo[5.2.1.02,6]dec-4-en-8-yl)-ethanone: Their Synthesis, Chemical Relationship and Comparison with Similar Compounds

Abstract  

The molecular and crystal structures of 8-benzyl-5-phenyl-3-oxa-4,8-diaza-tricyclo[5.2.1.0^2,6]dec-4-ene 11a and 1-(9-ethoxy-5-phenyl-3-oxa-4,8-diaza-tricyclo[5.2.1.0^2,6]dec-4-en-8-yl)-ethanone 13a have been XRD determined. The compounds crystallize in the monoclinic system with space groups P2₁/n and P2₁/c, respectively. The synthesis and chemical relationship between the two compounds are reported and their structures are compared with others of the aza-norbornene and isoxazoline families.     

Ultrasonics promoted synthesis of thiazolidinones from 2-aminopyridine and 2-picolilamine

The efficient multicomponent synthesis of thiazolidinones from the reaction of arenealdehydes, mercaptoacetic acid and 2-picolilamine or 2-aminopyridine under ultrasound irradiation are reported. The reaction with 2-aminopyridine needs a Lewis acid catalysis to afford the corresponding 2-aryl-3-(pyridin-2-yl)-1,3-thiazolidin-4-ones. All novel compounds were identified and characterized by (1)H and (13)C NMR spectra. Applying the sonochemical methodology, two series of heterocyclic thiazolidinones were synthesized in good yields after short reaction times.     

Ultrasound-assisted synthesis of aliphatic acid esters at room temperature

This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions.     

Antifungal activity, toxicity and chemical composition of the essential oil of Coriandrum sativum L. fruits

The aims of this study were to test the antifungal activity, toxicity and chemical composition of essential oil from C. sativum L. fruits. The essential oil, obtained by hydro-distillation, was analyzed by gas chromatography/mass spectroscopy. Linalool was the main constituent (58.22%). The oil was considered bioactive, showing an LC?? value of 23 μg/mL in the Artemia salina lethality test. The antifungal activity was evaluated against Microsporum canis and Candida spp. by the agar-well diffusion method and the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were established by the broth microdilution method. The essential oil induced growth inhibition zones of 28 ± 5.42 and 9.25 ± 0.5 for M. canis and Candida spp. respectively. The MICs and MFCs for M. canis strains ranged from 78 to 620 and 150 to 1,250 μg/mL, and the MICs and MFCs for Candida spp strains ranged from 310 to 620 and 620 to 1,250 μg/mL, respectively. C. sativum essential oil is active in vitro against M. canis and Candida spp. demonstrating good antifungal activity.