Ruthenium,osmium and rhodium-2,3-bis(2′-pyridyl)quinoxaline complexes

Ru₃(CO)₁₂ reacts with 2,3-bis (2-pyridyl)quinoxaline (dpq) in benzene in the presence of either 2,2(dipyridine (dpy) or pyridine (py) to give the mononuclear complexes Ru(CO)₃(dpq) (1) and Ru(CO)₂(dpq)(py) (2), respectively. On the other hand, reactions of Os₃(CO)₁₂ with dpq alone, or in the presence of dipyridine, yield only Os(CO)₃(dpq) (3). Spectroscopic studies of the three complexes were consistent with the proposed structures. Reactions of RuCl₃ with dpq, under reduced pressure in PhH/EtOH gave bis-[Ru(dpq)₂Cl₂]Cl (4). Magnetic measurements showed Ru^III, d⁵, to be in a low-spin electronic configuration. Three complexes, Rh₂(dpq)₂Cl₆ (5), [Rh(dpq)₂Cl₂]Cl (6) and Rh(dpq)(py)Cl₃ (7), were isolated from reactions of RhCl₃ with dpq. The type of product was dependent on the reactants and conditions. The complexes exhibit either irreversible or quasi-reversible ligand-based reductions. In addition, the zerovalent complexes (1)–(3) displayed one metal(based oxidation in their cyclic voltammograms, due to the formation of M⁺ species.     

Kinetic Current-Convective Instability in Hot Electron Plasma

The kinetic current-convective instability excited in a hot electron plasma, i.e. for T_e ? T_i, is investigated in the linear stage. Density and temperature of plasma components have gradients along the x-direction. In the absence of longitudinal current (u = 0) and homogeneous temperature the instability is also excited with maximum growth rate much exceeding that obtained in the case of u ≠ 0. Gradual increasing of the ion temperature over that of the electrons and a large density gradient leads to reduce the instability in the linear stage.     

POLYMERIZATION OF N,N''''-(PYROMELLITOYL)-BIS-L-LEUCINE DIACID CHLORIDE WITH HYDANTOIN DERIVATIVES BY MICROWAVE IRRADIATION

INTRODUCTIONRecently, there has been growing interest in applying microwave energy to synthetic organic chemistry[1-4],sample preparation for analysis[5], extraction of natural products from plants[6], waste treatment[7] and polymersynthesis[8-13]. The reactions involved in these applications are very fast and are completed within a short periodof time. Recently, we have used microwave irradiation for the synthesis of poly(amide-imide)s and poly(ester-imide)s[14-17].Recently more attentio…     

Kinetic Buneman Instability in a Homogeneous Hot Electron Plasma

The development of Buneman kinetic instability in plasma with hot electrons and cold ions is investigated in the quasilinear approximation at current velocites close to the instability threshold values. It is shown that the contribution of electron's dielectric permeability in the dispersion equation is negligible and that quasilinear theory has in general stabilizing effect.     

Possible supersymmetric solution to the discrepancy between B-->phiK(S) and B-->eta'K(S) CP asymmetries

We present a possible supersymmetric solution to the discrepancy between the observed mixing CP asymmetries in B-->phiK(S) and B-->eta(')K(S). We show that, due to the different parity in the final states of these processes, their supersymmetric contributions from the R sector have opposite signs, which naturally leads to S(phiK(S)) not equal Seta(')(K(S)). We also consider the proposed mechanisms to solve the puzzle of the observed large branching ratio of B-->eta'K and their impact on Seta(')(K(S)).     

Studies in the formation of heterocyclic rings containing nitrogen

The mode of formation of keto-hexahydro-s-triazines has been studied by conducting the reaction in two stages. The experiments revealed that the condensation with aromatic aldehydes is more complex, and the mechanism is not clear, although in the case of aliphatic aldehydes the step-wise formation of hexahydro-s-triazines has been reported.     

Metallocyclopentadienyl derivatives of bivalent samarium,europium and ytterbium

It has been established that the reaction of metallocyclopentadienyl mercurials with an excess of elemental lanthanides Ln(Ln = Sm, Eu, Yb) in tetrahydrofuran yields substituted cyclopentadienyl derivatives of the metals.     

Vibrational anharmonicities revealed by coherent two-dimensional infrared spectroscopy

Two-dimensional infrared photon echo spectroscopy has been used to describe the anharmonic nuclear potential of two coupled molecular vibrations. The two-dimensional spectrum shows diagonal and off-diagonal features, each composed of two peaks. The splitting between these peaks is directly related to the anharmonicity, while the relative amplitude of the diagonal and off-diagonal features describes the projection angle between interacting dipoles.     

Novel synthesis of pyran,thiophene, and pyridine derivatives incorporating thiazole ring and their antitumor evaluation

This study aims to design and synthesize a number of novel pyran, thiophene, and pyridine derivatives incorporating thiazole ring and evaluate their antitumor inhibition (μM) as significant anticancer agents. The reactivity of compound 1 [2-(4-oxo-4,5-dihydrothiazol-2-yl)acetonitrile] towards different chemical reagents was described. Furthermore, the reactivity of all the newly synthesized products was evaluated. The most active compounds towards all the three tumor cancer cell lines used such as MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (CNS cancer), and normal fibroblasts human cell line (WI-38) were compounds 6d , 8 , and 10b , which compared with the antiproliferative effects of the reference control doxorubicin. Also, some of the novel compounds indicate higher inhibition than doxorubicin against some of the cancer cell lines used such as 6c (especially towards MCF-7) and 2b , 6b (especially towards SF-268).     

Cyclization of thiosemicarbazide derivative: As a source of novel synthesis of some azoles and azines

In our study, we aimed to synthesize novel, some biologically active compounds, Azoles and Azines derivatives, that to be nitrogen-containing heterocycles, and have their diverse therapeutic values. Thiosemicarbazide, 2 , was obtained from the attack of nitrogen of hydrazine to the carbon of heteroallene function of compound 1. Triazolotriazole derivative, 4 , was obtained from the reaction of 2 with diethyl malonate. Cyclization of thiourea unit of compound 2 with heteroallene, 1 , gave trazine, 6 . Benzolyation of 2 using benzoyl chloride formed triazole derivative, 8 . Reaction of 2 and maleic anhydride gave furothiadazine, 10. Cyclohexanopyrimidinthione, 12 , was obtained from cyclocondensation of cyclohexanone with 2. Triazole, 14 , was obtained from 2 and ammonium isothiocynate under thermal condition. Reaction of 2 with ethyl bromoacetate gave thiazole derivative, 16. [2+3] Cyclocondensation of acetyl acetone with 2 provided pyrazole, 18 . Triazolotriazole, 20 , was obtained from formalin and 2. Compound 2 suffers intramolecular base mediated cyclization affording pyrazole, 21. Keeping 2 and propinaldehyde under reflux provided triazolotriazole, 24. Acylation of 2 by succinic acid formed pyridazine derivative, 27.