Action du Tris(Diméthylamino)phosphine et de l'Oxyde de P,P-dichlorophenylphosphine sur les N 1Tosylamidrazones: Obtention des 3-(Dimethylamino) 1,2,4,3-triazaphospholines et des 3-Oxo1,2,4,3-triazaphospholines

The reaction of N¹-tosylamidrazones with tris(dimethylamino)phosphine and P,P-dichlorophenylphosphine oxide provides respectively a convenient access to the new 3-(dimethylamino)-1,2,4,3-triazaphospholines and 1,2,4,3-triazaphosphlines-3-oxide. The structure of all obtained products is confirmed by NMR (¹ H, ³¹ P, ¹³C) and IR spectroscopy.     

Photophysical parameters and fluorescence quenching of 7-diethylaminocoumarin (DEAC) laser dye

The optical properties including electronic absorption spectrum, emission spectrum, fluorescence quantum yield, and dipole moment of electronic transition of 7-diethylaminocoumarin (DEAC) laser dye have been measured in different solvents. Both electronic absorption and fluorescence spectra are red shifted as the polarity of the medium increases, indicating that the dipole moment of molecule increases on excitation. The fluorescence quantum yield of DEAC decreases as the polarity of solvent increases, a result of the role of solvent polarity in stabilization of the twisting of the intramolecular charge transfer (TICT) in excited state, which is a non-emissive state, as well as hydrogen bonding with the hetero-atom of dye. The emission spectrum of DEAC has also been measured in cationic (CTAC) and anionic (SDS) micelles, the intensity increases as the concentration of surfactant increases, and an abrupt change in emission intensity is observed at critical micelle concentration (CMC) of surfactant. 2×10⁻³ mol dm⁻³ of DEAC gives laser emission in the blue region on pumping with nitrogen laser (λ_ex=337.1 nm). The laser parameters such as tuning range, gain coefficient (α), emission cross section (σ_e), and half-life energy have been calculated in different solvents, namely acetone, dioxane , ethanol, and dimethyforamide (DMF). The photoreactivity of DEAC has been studied in CCl₄ at a wavelength of 366 nm. The values of photochemical yield (?_c) and rate constant (k) are determined. The interaction of organic acceptors such as picric acid (PA), tetracyanoethylene (TCNE), and 7,7,8,8-tetracynoquinonedimethane (TCNQ) with DEAC is also studied using fluorescence measurements in acetonitrile (CH₃CN); from fluorescence quenching study we assume the possible electron transfer from excited donor DEAC to organic acceptor forming non-emissive exciplex.     

On the limit polynomial for a solution of an elliptic equation of the fourth order with constant coefficients

We show that a solution of the Dirichlet problem for an elliptic equation of the fourth order with constant coefficients, whose right-hand side is periodic in all variables except one and exponentially decreases, converges at infinity to a certain polynomial of the first degree in the nonperiodic variable. Coefficients of this polynomial are determined. Institute of Mathematics, Ukrainian Academy of Sciences, Kiev. Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 3, pp. 437–444, March, 1998.     

2,3-Seco-2,3-dioxo-lyngbyatoxin A from a Red Sea strain of the marine cyanobacterium Moorea producens

Chemical investigation of the organic extract of a Red Sea strain of the cyanobacterium Moorea producens has afforded 2,3-seco-2,3-dioxo-lyngbyatoxin A (1). Five known compounds including lyngbyatoxin A (2), majusculamides A and B (3 and 4), aplysiatoxin (5) and debromoaplysiatoxin (6) were also isolated. Their structures were elucidated by using HR-FAB-MS, 1D and 2D NMR analyses. The compounds were evaluated for antiproliferative activity against HeLa cancer cells. Lyngbyatoxin A (2) showed potent activity, with an IC₅₀ of 9.2 nM, while 5 and 6 displayed modest activity with IC₅₀ values of 13.3 and 3.03 μM, respectively. In contrast, compounds 1, 3 and 4 were inactive, with IC₅₀ values greater than 50 μM. The lack of cytotoxicity for 2,3-seco-2,3-dioxo-lyngbyatoxin A (1) demonstrates that the indole moiety in lyngbyatoxin (2) is essential for its cytotoxicity, and suggests that detoxification of 2 may be carried out by biological oxidation of the indole moiety to yield 1.     

Pyridazine Derivatives and Related Compounds,Part 221: Synthesis,Reactions, and Insecticidal Activity of 3-Amino-5,6-diaryl-1H-pyrazolo[3,4-c]pyridazines

Starting with 3-amino-5,6-diaryl-1H-pyrazolo[3,4-c]pyridazine, the syntheses of thiourea derivatives, dithiocarbamates, ethyl carbamate, phosphoranylidene amino, and substituted acetamido derivatives are described. The products were screened for their insecticidal activity against Mucsa, domestica, and Aphid, Macrosiphum pisi.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Radiation Polymerization of 4-(Acryloylamido)benzonitrile: Zinc and Copper Complexes

The new polymer containing cyano groups was synthesized by γ-irradiation. The oximated polymer was prepared using hydroxylamine hydrochloride in basic medium. The characterization of monomer, polymer, and oximated ones was confirmed by infrared and nuclear magnetic resonance spectroscopy. The complex formation of the amidoxime salt towards Zn^II, Cu^II, and Zn^II/Cu^II mixture in aqueous solution was studied by atomic absorption spectroscopy, energy dispersive spectroscopy, and electron spin resonance spectrometry. The significant binding capacity of these metal ions revealed its selectivity to Zinc(II) ion. The thermal stability of polymers and complexed ones was investigated using thermogravimetry analysis. The change in their morphology was observed by scanning electron microscopy (SEM).     

The mechanism of aromatic nitration by tetranitromethane

Aromatic nitrations by tetranitromethane are shown to be photo-chemically initiated and are believed to proceed via trinitromethyl nitrite.     

New mathematical identities with applications to flexure and torsion

We obtain some new trigonometric identities and find the corresponding Chebyshev polynomials identities. We also indicate their applications to certain boundary value problems which arise in Mechanics.