The photogalvanic effect of Fe(II)-β-diketonate/thionine systems in aqueous acetonitrile

Summary The photogalvanic effect of ferrousbis-(acetylacetonate) (Fe(II)(acac)₂) and ferrousbis-(trifluoroacetylacetonate) (Fe(II)(tfac)₂) complexes in aqueous acetonitrile thionine dye solutions has been studied in a photogalvanic cell of 70 cm³ capacity with identical platinum electrodes (area: 0.25 cm²) using visible light (80 mW/cm²) at 25°C. The theoretical Sunlight Engineering Efficiency (SEE) was determined for both complexes and it was found that the best SEE was obtained when Fe(II)(tfac)₂ was used at a concentration of 1.5×10^–4 mol/dm³ with a thionine concentration of 1×10^–4 mol/dm³ atpH=4 in 40% aqueous acetonitrile. Effects of incident light intensity and temperature on the photogalvanic performance and the action spectrum of the present system were also investigated. A mechanism of the photoredox reaction between the Fe(II)-complex and the dye molecule is proposed.

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Der photogalvanische Effekt von Fe(II)-w6rrm4v1937/xhuge946.gif" alt="beta" align="MIDDLE" BORDER="0">-Diketonat/Thionin-Systemen in wäßrigem Acetonitril

Zusammenfassung Der photogalvanische Effekt von Eisen(II)-bis-(acetonylacetonat) (Fe(II)(acac)₂) und Eisen(II)-bis-(trifluoracetylacetonat) (Fe(II)(tfac)₂ in wäßriger acetonitrilischer Thioninlösung wurde in einer photogalvanischen Zelle (70 cm³) mit identischen Platinelektroden (Fläche: 0.25 cm²) mit sichtbarem Licht (80 mW/cm²) bei 25°C untersucht. Für beide Komplexe wurde die theoretische Sunlight Engineering Efficiency (SEE) bestimmt; der beste SEE-Wert wurde für Fe(II)(tfac)₂ bei einer Konzentration von 1.5×10^–4 mol/dm³ beipH=4 in 40%igem Acetonitril gefunden (Thioninkonzentration: 1.0×10^–4 mol/dm³). Effekte, die durch Änderung der Lichtintensität und der Temperatur hervorgerufen werden, werden diskutiert. Ein Mechanismus für die Photoredoxreaktion zwischen dem Fe(II)-Komplex und dem Farbstoffmolekül wird vorgeschlagen.

     

Terpenes in organic synthesis

A seven-step synthesis ofS-(+)-hydroprene (S-1) in w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">20 % overall yield starting fromS-(+)-3,7-dimethyl-1,6-octadiene (2) of 55+-10 % optical purity is described. The introduction of an optical enhancement step in the synthetic sequence at the stage ofS-(–)-3,7-dimethyl-1-octanol (9) raises the optical purity ofS-1 from w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">50 % to w037843t2/xxlarge8764.gif" alt="sim" align="MIDDLE" BORDER="0">80 %.For part 13, see. ref.¹ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–348, February, 1993.     

A new theoretical approach to the empirical resonance energies of the aromatic hydrocarbons

In the framework of the Hückel MO approximation, the differences in total binding energy between a given molecule and the corresponding distorted Kekulé-type structure are calculated for a variety of benzenoid hydrocarbons. The total binding energy is assumed to be given by the sum of the w88j6287438g48/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-electron and w88j6287438g48/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0">-electron binding energies. It is shown that there is a good linear relationship between the calculated differences in total binding energy and the w88j6287438g48/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-electron delocalization energies (DE) as obtained by using the simple Hückel MO method. This provides a physical basis for the use of the w88j6287438g48/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-electron DE as a theoretical index to the empirical resonance energy (RE). Further, by examining the changes in w88j6287438g48/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-electron binding energy between a given molecule and the corresponding distorted Kekulé-type structure, it is concluded that in benzenoid hydrocarbons the main contributor to the RE is not the w88j6287438g48/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0">-electron DE but the compressional energy of w88j6287438g48/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0"> bonds.     

Trans-cis Photoisomerization of 1-Methyl-4-(4′-hydroxystyryl)pyridinium in inclusion complexes ofβ-cyclodextrin and its derivatives

The effects of w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-CyD), heptakis(2,6-di-O-methyl)-w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (DMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD) and heptakis(2,3,6-tri-O-methyl)-w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin (TMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD) ontrans-cis photoisomerization of 1-ethyl-4-(4w380n14522661410/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-hydroxystyryl)pyridinium (POH) have been studied in aqueous solutions. The ratio of [cis]/[trans] for POH in the photostationary state at pH 8.54 was remarkably reduced by the presence of w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD or DMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD. The reduction of the [cis]/[trans] ratio in the photostationary state was explained in terms of the shift of the equilibrium of POH ₊ ^trans w380n14522661410/xxlarge8652.gif" alt="rlhar" align="MIDDLE" BORDER="0"> PO _trans + H^– toward PO _trans formation. The binding constants of w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD and DMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD for PO _trans were 2.00- and 1.36-fold larger than those for POH ₊ ^trans , respectively. The binding constants of TMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD for both species are much smaller than those of w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD and DMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD. This result indicates that PO _trans , which has a betain structure, forms stable complexes with w380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD and DMw380n14522661410/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">CyD with its hydrophobic parts inside and the charged parts outside the CyD cavities.     

Influence of cyclodextrins on nitrosation of drugs

The World Health Organization issued a nitrosation procedure (NAP Test) which allows to carry out nitrosation under standard conditions. It has proved that the in vitro reaction rates of the fast nitrosatable drugs piperazine, cimetidine and ethambutol are not influenced by w503/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-, w503/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">- and w503/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-cyclodextrin. On the contrary, w503/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-, w503/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-cyclodextrin and heptakis-2,6-di-O-methyl-w503/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-cyclodextrin enhance the nitrosation of the slower nitrosatable 1-ephedrine and fencamfamine significantly. This possible reaction must be considered if nitrosatable drugs are formulated with cyclodextrins to be administered to human beings.     

Synthesis and ozonization of (+)-4α-(1-trimethylsilyloxyethen-1-yl)-2-carene

(+)-4w3/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1984–1987, October, 1995.     

Root determination by use of Padé approximants

In this paper we describe a new technique for generating iteration formulas — of arbitrary order — for determining a zero (assumed simple) of a functionf, assumed analytic in a region containing the zero. The 1/p Padé Approximant (pw832w32067v3/xxlarge8807.gif" alt="gE" align="MIDDLE" BORDER="0">0) to the functiong(t)w832w32067v3/xxlarge8801.gif" alt="equiv" align="MIDDLE" BORDER="0">f(z) is formed wherez=w+t, using the Taylor series forf at the pointw, an approxination to the zero off. The value oft for which the 1/p Padé Approximant vanishes provides the basis of iteration formulas of orderp+2.Some known iteration formulas, e.g., Newton-Raphson's, Halley's and Kiss's of order of convergence two, three and four, are directly obtained by settingp=0,1 and 2, respectively.     

Waveform control for magnetic testers using a quasi-Newton method

A nonlinear iterative learning algorithm is proposed to make a voltage waveform in the secondary coil sinusoidal in this paper. The algorithm employs a globally convergent Jacobian-free quasi-Newton type solver that has a BFGS-like structure. This method functions well, and it is demonstrated using typical soft magnetic materials.     

Figures of merit of magnetostrictive single crystal iron-gallium alloys for actuator and sensor applications

Energy density, magnetomechanical coupling factor and a dimensionless sensing gage factor of 〈1 0 0〉 oriented single crystal iron-gallium alloys with 16, 17.5, 19, 24.7 and 29 at% gallium were studied as functions of stress and magnetic field. To estimate these quantities, the samples were characterized under different quasi-static stress and magnetic field conditions. The experimental behavior was modeled using an energy-based non-linear approach. Both the experimental data and the model simulations were used to calculate material parameters such as magnetic permeability, piezo-magnetic strain coefficient (d₃₃), inverse piezo-magnetic coefficient (stress sensitivity, d*₃₃) and Young's modulus in the material. These quantities were used to obtain energy density, magnetomechanical coupling factor and sensing gage factor as functions of magnetomechanical conditions. Maximum energy density of around 3 kJ/m³, magnetomechanical coupling factor higher than 0.75 and sensing gage factor on the order of 10³ were calculated.     

Water-in-Oil-in-Water Nanoemulsions Containing Temulawak (Curcuma xanthorriza Roxb) and Red Dragon Fruit (Hylocereus polyrhizus) Extracts

Hydrophobic curcumin in temulawak extract and hydrophilic betacyanin in red dragon fruit extract are high-value bioactive compounds with extensive applications in functional food. In this study, these extracts were encapsulated in water-in-oil-in-water (w/o/w) nanoemulsions as a delivery system using a two-step high-energy emulsification method. PGPR and Span 20 were used as lipophilic emulsifiers for the primary w/o emulsion. The most stable w/o/w formulation with the least oil phase separation of 5% v/v consisted of w/o emulsion (15% w/w) and Tween 80 (1.5% w/w) as hydrophilic emulsifier. The formulation was characterized by a 189-nm mean droplet diameter, 0.16 polydispersity index, and –32 mV zeta potential. The freeze–thaw stability may be attributed to the combination of low w/o emulsion content and high Tween 80 concentration in the outer water phase of the w/o/w nanoemulsions used in this study. The IC₅₀ values of the nanoemulsion and the red dragon fruit extract were similar. It means that the higher concentration of curcumin in the nanoemulsions and the lower IC₅₀ value of temulawak extract ensured sufficient antioxidant activities of the w/o/w nanoemulsions.