INCREASED QUANTUM YIELD OF PHOTOREDUCTION OF DYES (A CATALYTIC EFFECT)

Abstract— While studying the photoreduction of some dyes (D) by reducing agents (R), it was observed that the quantum yield of the photoreduction increases considerably upon addition of a third substance (C), whereas it is very small when the dye is photoreduced by C alone (catalytic effect), (see Table 1).
The system thionine (D), allylthiourea (R), and azulene (C) was investigated in detail using both flash photolysis and continuous illumination. On photolysis, thionine is converted into its photo-reduced form, leucothionine. Azulene reacts with the basic form of the thionine triplet ³ TH ⁺ to produce the semithionine radical. In the system thionine and azulene, most of these radicals revert back to thionine. When ATU (˜ 10^2- M ) is added to thionine and azulene (3 × 10^-4 M ), the semithionine radicals are reduced to leucothionine; the quantum yield of this reduction is considerably higher than in the system thionine and allylthiourea. Flash experiments demonstrate that allylthiourea does not react with the semithionine radicals.
At very high ATU concentrations (≥ 10^-1 M ), however, the primary reaction is between thionine triplet and allylthiourea; under these conditions the quantum yield is not influenced by azulene (3 × 10^-4 M ).     

Über die Hypergolität von Silylhydrazinen

Zusammenfassung Das Zündverhalten von mehr als 20 organylsilylsubstituierten Hydrazinen mit conc. Salpetersäure, Fluor, flüssigem Sauerstoff, mit O₂ verdünntem gasförmigen Ozon und mit verflüssigtem O₃ wurde beobachtet und im Falle HNO₃ auch mit einer schnell-laufenden Kamera gemessen. Die wesentlichsten Resultate können aus Tab. 1 und den Abb. 1 bis 4 entnommen werden.

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The hypergolic behaviour of more than 20 organosilyl substituted hydrazines in contact with conc. HNO₃, with gaseous F₂, with liquid O₂, with liquid O₃ and with gaseous O₃ (diluted with O₂), was observed and, in the case of conc. HNO₃, was registered by a fastrunning camera. The most interesting results are to be seen in table 1 and in pictures 1 to 4.

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Mit 4 Abbildungen

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60. Mitt.:U. Wannagat undF. Höfler, Mh. Chem.97, 976 (1966).

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Zugleich 11. Mitt. über Silicium—Hydrazin-Verbindungen; 10. Mitt.:H. Bürger undF. Höfler, Mh. Chem.97, 984 (1966).

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Auszüge aus der DiplomarbeitF. Höfler, T. H. Graz 1964.     

Coupling of narrow-bore liquid chromatography to thin-layer chromatography : Part I. Interfacing

The coupling of liquid chromatography (l.c.) on narrow-bore columns to thin-layer chromatography (t.l.c.) is described. The effluent from a l.c. column can be deposited on a t.l.c. plate after a normal-phase or reversed-phase separation without serious loss of chromatographic information. Both silica and alkyl-modified silica plates can be used for storage. The interface is a fused silica capillary which connects the column outlet to the spray jet assembly of a Linomat applicator for t.l.c. The stored chromatogram can serve as starting point for a new separation, but also allows the use of detection principles which are normally not compatible with l.c. The chromatography of some polynuclear aromatic hydrocarbons is used to illustrate the possibilities of the combinations.     

Beiträge zur Chemie des Phosphors. 167 [1, 2]. Konstitutions- und Konfigurationsisomere von Pentaphosphan(7), P5H7

Contributions to the Chemistry of Phosphorus. 167. Constitutional and Configurational Isomers of Pentaphosphane(7), P₅H₇ Phosphane mixtures containing 10—15 P-% of pentaphosphane(7), P₅H₇, are obtained by thermolysis of diphosphane, P₂H₄, or as residue from distillation of crude diphosphane [3]. According to the complete analysis of the ³¹P{¹H}-NMR spectrum on the basis of selective population transfer experiments, P₅H₇ exists as a mixture of three diastereomers of n-P₅H₇ — 1a (erythro, erythro), 1b (erythro, threo), 1c (threo, threo) — and of the constitutional isomer 2-phosphinotetraphosphane 2 (iso-P₅H₇, largest relative isomeric abundance). The correlation between the diastereomers and the observed spin systems results from the preferred gauche orientation of neighboring free electron pairs, the dependence of ¹J(PP) on dihedral angles, and the ³J(PP) long range couplings. From the ³¹P-NMR data of the phosphane molecules P_nH_n+2 with n = 1—5 general relationships for the δ(³¹P) values and the ¹J(PP) coupling constants of chain-type phosphorus hydrides as a function of their structural parameters are derived.     

Investigation of alkaloid N-oxides by secondary-ion mass spectrometry

An advantage of theSIMS method for investigating alkaloid N-oxides has been shown. In the case of N-oxides of steroid, diterpene, tropane, and pyrrolizidine alkaloids, fragments including the oxygen of the N-oxide group are revealed. The protonation of N-oxide molecules in a glycerol matrix takes place mainly through the negatively polarized oxygen atom of the N-oxide function. On fragmentation, theMH ⁺ ions of N-oxides of monoester tropane and pyrrolizidine alkaloids tend to form fragmentary ions of the protonated forms of the aminoalcohols (A+). The energies of the metastable transitionsMH ⁺ A⁺ have been calculated for the Noxides of the pyrrolizidine alkaloids viridif lorine, trachelanthamine, and echinatine.Institute of the Chemistry of Plant Substances [IKhRV], Academy of Sciences of the Republic of Uzbekistan [AN RUz], Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 833–837, November-December, 1995. Original article submitted February 20, 1995.     

Liquid chromatography with post-column electrochemical treatment and mass spectrometric detection of non-polar compounds

The first hyphenation of high performance liquid chromatography (HPLC), electrochemical online oxidation and mass spectrometry (MS) is described. Ferrocenecarboxylic acid esters of various alcohols and phenols have been synthesized, separated by reversed-phase HPLC and oxidized (ionized) coulometrically prior to single quadrupole MS analysis using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) interfaces. The dependence of the ionization on the electrochemical pretreatment is demonstrated. Limits of detection for selected derivatives range from 4 x 10(-9) to 4 x 10(-7) mol dm-3 depending on the individual compound and the selected interface.     

Simultaneous measurement of gamma-rays and neutron fluences</p> using a HPGE detector</o:p></p> </p>

Summary A simultaneous determination of gamma and neutron fluences in a mixed neutron + gamma field can be achieved by gamma-ray spectrometry, optimizing the moderator-converter-detector assembly and measuring both the direct gamma-lines and the neutron induced prompt gammas. For the prompt gamma-lines a combination of high efficiency and low background is the goal, and it can be best achieved if the gamma-energy is in the range above about 1 MeV up to 2.5 MeV. The optimal moderator-converter thickness can be determined experimentally. Most converter elements produce gamma-rays in the low energy range. If chlorine is used as a converter, the 1164.7 keV peak and the 1950-1960 keV peaks seems to be a good choice. A very practical material containing chlorine is PVC. It is an efficient moderator, it is solid, common, and can be handled easily.</p> </p>     

Study of hydrogen adsorption on iridium catalysts

The influence of dispersity on hydrogen adsorption on Ir black and Ir/C catalysts has been studied. It is shown that supported iridium reduces the heat of hydrogen adsorption as compared to Ir black. With decreasing catalyst dispersity, the amount of weakly bound hydrogen increases, while its adsorption heat decreases on all Ir catalysts.

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Ir- Ir/C-. , Ir-. C , Ir-.

     

The glyceride complex of the seed oil ofOnopordum acanthiium

Summary The complex mixture of glycerides of a seed oil containing oxidized aryl radicals in the triglycerides (10 groups of glycerides) has been separated for the first time. New groups of monohydroxyacyl triglycerides (oxoacyl, 0.1% of the oil, and hydroperoxyacyl, 0.1%) and di(oxyacyl)triglycerides (epoxacyl-hydroxyacyl, 0.36%) have been detected and isolated.A new -oxodienoic acid has been found for which the following structural formula is proposed as the most probable: 11-oxooctadeca-cis-9,cis-12-dienoic acid.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 699–707, November–December, 1978. Original article submitted June 27, 1978.     

Theoretical study on geometry and spectroscopic properties of 1,1′-binaphthyl in the electronic ground and first excited singlet states

Equilibrium geometries for the electronic ground and first excited singlet states of 1,1'-binaphthyl have been calculated by minimization of the total energy with respect to all internal coordinates. Using these results, an interpretation of the fluorescence S₁→ S₀ and absorption spectra S_m ← S₀ and S_n ← S₁ in rigid and fluid solutions is given.For the first time the equilibrium geometry of the first excited singlet state of 1, 1′-binaphthyl has been calculated. On excitation to the S₁ state the dihedral angle θ between the two naphthalene moieties is de- creased from 61 ° to 41 °. A detailed survey of CH bond lengths in the S₀ and S₁ states has been given. This result should be of particular importance for the theoretical treatment of radiationless transitions.Using equilibrium geometries for the S₀ and S₁ states a satisfactory interpretation of the S_m ← S₀ and S_n ← S₁ absorption spectra as well as of the fluorescence spectra in fluid and rigid solutions can be given. Concerning the S_n ← S₁ absorption spectrum in fluid solution, the calculations predict a strong absorption (A ← B transition) in the still uninvestigated region of energies lower than 11000 cm^?1.From the results of this paper and of other calculations it can be concluded that the Warshel-Karplus method yields reliable equilibrium geometries for electronic ground and excited states of unsaturated hydrocarbons [22,23].