Synthesis and spectroscopic properties of (N/O) mono- and dispirocyclotriphosphazene derivatives with benzyl pendant arms: study of biological activity

The Cl replacement reactions of hexachlorocyclotriphosphazene (trimer; N ₃ P ₃ Cl ₆ ) with sodium (N-benzyl)- aminopropanoxides (1 and 2) produced monospiro- (3 and 4), cis-, and trans-dispirocyclotriphosphazenes (13–16). The monospiro tetrakis-aminocyclotriphosphazenes (5–12) were obtained by the Cl substitutions of 3 and 4 with different secondary amines. The cis- (13 and 14) and trans-dispirophosphazenes (15 and 16) possessed 2 chiral P centers, and they were able to present meso and racemic forms, respectively. Moreover, the structures of compounds 5 and 14 were designated using X-ray data. The absolute configuration of compound 14 was found as SR in the solid state. Analytical and spectroscopic data of the phosphazenes were consistent with their suggested structures. Antimicrobial activities of the benzyl-pendant-armed cyclotriphosphazenes were scrutinized against G(+) and G(−) bacteria and yeast strains. The bacterium most affected by the synthesized compounds was Pseudomonas aeruginosa . Minimum inhibitory concentrations and minimal bacterial concentrations were in the range of 125–500 μM. Interactions between the phosphazenes (3–12 and 15) and plasmid DNA were studied with agarose gel electrophoresis. The phosphazene- DNA interaction studies of the cyclotriphosphazenes revealed that phosphazenes 3, 4, and 15 had a substantial effect on supercoiled DNA by cleavage of the double helix.     

Fluctuation Anomalies of the Gravitational Center of the Raman Scattering OH Band in Water

Physics of Wave Phenomena - Anomalously large fluctuations are experimentally found for the gravitational center of the OH band envelope of the Raman scattering of 10-ns pulses in water. Upon...     

Evaluation of the surface properties of 4-(Decyloxy) benzoic acid liquid crystal and its use in structural isomer separation

The selectivity of 4-(Decyloxy) benzoic acid (DBA) liquid crystal in surface adsorption region (303.2–328.2 K) and thermodynamic region (423.2 – 433.2 K) was investigated by inverse gas chromatography at infinite dilution (IGC-ID). The selectivity parameters of the structural isomer series named butyl acetate, butyl alcohol, and amyl alcohol series were calculated for the DBA using IGC-ID technique. Additionally, the surface properties including dispersive surface energy (gS D), free energy (DGA S), enthalpy (DHA S), and acidity-basicity constants were calculated with net retention volumes obtained from IGC-ID experiment results. When the DHA S and DGA S are constants, DBA surface was found to be an acidic character (KD/KA @ 0.89).     

UVRR spectroscopic studies of valinomycin complex formation in different solvents

We investigated the complexation of valinomycin (VM) in different solvent environments with the aid of the UVRR spectroscopy. By probing the 206.5 and 229 nm excited Raman spectra, we showed that new bands are observed around 1700 and 1290 cm(-1). We assigned the 1700 cm(-1) band to the hydrogen bonded ester carbonyl stretching vibration. In a polar solvent, VM-K(+) complexation shows significant intensity changes in amide and ester carbonyl stretching region. Because of the small amount of conformational interconversion, complexation has a negligible effect on other band intensities including, the amide III, C(alpha)H, and amide II. We also showed the effects of the solvent polarity on the solution conformation of VM.     

Measurement of the matrix element for the decay η′ → ηπ 0 π 0 with the GAMS-4π spectrometer

The parameters of the Dalitz diagram for the decay η′ → ηπ ⁰ π ⁰ in a generalized and a linear representation were determined by using a statistical sample of 15 × 10³ events. A charge-exchange reaction at a momentum of 32 GeV/c was a source of monoenergetic η′ mesons. The experiment was performed with the aid of the GAMS-4π spectrometer.     

Multiple bicyclic diamide-lutetium complexes in solution: chemometric analysis of deep-UV Raman spectroscopic data

The investigation of complex formation between a bicyclic diamide, a novel chelating agent for lanthanides and actinides, and lutetium in an acetonitrile solution is reported. A free ligand and its lutetium complexes showed weak, noncharacteristic near-UV absorption and no fluorescence, which limited the application of absorption and fluorescence spectroscopies for studying this system. Deep-UV Raman spectroscopy combined with chemometric analysis was shown to be a powerful tool for quantitative characterization of multiple equilibria between lutetium and a bicyclic diamide. Several chemometric methods were utilized for a comparative analysis of Raman spectroscopic data. It was found that a recently developed stepwise maximum angle calculation algorithm followed by alternative least squares (ALS) was more efficient than the commonly used combination of evolving factor analysis and ALS methods, especially when little or no information about the system composition and the spectra of individual components was available. A free ligand and 1:1, 1:2, and 1:3 metal-ligand complexes were distinguished in a bicyclic diamide-lutetium solution. The composition evolution of the solution during the course of titration with lutetium was described, and the stepwise stability constants of complex formation, K(1):K(2) = 0.80 +/- 0.15 (K(1,2) > 10(8) M(-1)) and K(3) = (5.5 +/- 1) x 10(3) M(-1), were estimated.     

Study off o (995) resonance in the π0π0 decay channel

A high-statistics study of the π⁰π⁰-system produced in the π^- p→π⁰π⁰ n reaction at 38GeV/c has been carried out at the IHEP accelerator using the GAMS-2000 multiphoton spectrometer. A partial-wave analysis which includesS, D ₀, D_? andD ₊ waves has been performed in the |t|-range up to 1 (GeV/c)². TheS ^*/f ₀(980) resonance is seen as a dip in theS-wave amplitude at small |t|. A distinct peak with a mass of 997±5MeV and a width of 48±10MeV is observed in theS-wave at |t|>0.3 (GeV/c)². The production cross sections are measured.     

Observation of a spin 4 neutral meson with 2 GeV mass decaying in π° π°

The invariant mass spectrum of neutral meson states from π^?p interactions at 40 GeV/c incident momentum has been investigated in a high statistics experiment performed at the 70 GeV IHEP accelerator. To detect the high energy photons coming from the produced neutral states, a hodoscope spectrometer with a computer on-line was used. A clear structure on the mass spectrum of dipions produced in the reaction π^?p→π°π°n is observed at 2 GeV. The decay angular distributions show in this mass region the variation with mass typical of a state with a spin J = 4. The mass of the observed meson is found to be M = (2020±30)MeV and the estimate of the full width is (180±60) MeV.     

Raman spectroscopic study of the tautomeric composition of adenine in water

An experimental and theoretical study of the tautomeric composition of adenine (Ade) in water using Raman spectroscopy is reported. Experimental resonance Raman spectra of adenine at excitation wavelengths of 200, 218, and 266 nm were compared with quantum-mechanical calculations of N(9)H- and N(7)H-adenine tautomers and their cations. Both theoretical and experimental studies of nonresonance Raman spectra (457 nm excitation) of adenine were also performed for comparison. A satisfactory agreement of the calculated results with the experimental data was obtained. The Raman spectra are interpreted, and the basic regularities of the Raman intensity distribution are explained. On the basis of the analysis performed, the tautomeric composition of adenine in water is revealed. It is shown that the Ade-N(9),N(1)H(+) cation is the predominant form and that some neutral forms of Ade-N(9)H and Ade-N(7)H tautomers exist in water at pH 3.     

Laser ablation of alloys: Selective evaporation model

A mechanism of non-stoichiometric laser ablation is proposed and experimentally verified for multicomponent alloys. The analysis of four-component bronze samples in various excitation modes and the recorded laser plasma spectra revealed that disproportion of plasma elements during laser evaporation arises from selective evaporation of components at the heating-melting-evaporation stage. Correction coefficients proportional to the work function of the alloy component vapor in the heating-melting-evaporation cycle are calculated for the plasma spectrum. Correction procedure for the spectral lines leads to a good agreement of the measured sample composition with the tabulated data. To check that the proposed approach is universal, aluminum alloys and iron alloys (high-alloy stainless steels) are analyzed. It is found that selective evaporation for aluminum alloys is lower than for bronzes. Evaporation selectivity was insignificant for stainless steels. The proposed mechanism for selective evaporation during laser ablation and correction of the plasma spectrum make it unnecessary to use a standard in the quantitative elemental analysis of complex bronze and aluminum alloy samples.