Photopyroelectric spectroscopy (P2ES) of electronic defect centers in crystalline n-CdS

The electrical and dielectric properties of mercuric iodide were studied at room temperature under various intensities and colours of light in the frequency range 1 Hz–10 kHz. In the high-frequency region (>40 Hz), the real part of the dielectric constant () is almost constant with frequency (f), colour and intensity of light. At lower frequencies, varies nearly as 1/f and monotonically increases with intensity (I) of the yellow (or green) light, whereas it is almost constant with red light intensity. This behaviour is discussed in the view of the different polarization contributions. The imaginary part of the dielectric constant () was found to vary as 1/f over the frequency range studied. This behaviour was observed whether the crystal was in dark or illuminated implying that the roomtemperature ac dark- or photo-conductivity () is independent of frequency. The observed variation of with intensity of yellow (or green) light was found to follow anI ^1/2 dependence and a weaker dependence for the red light. the red light. The conductivity behaviour is discussed in the view of the current theories.     

A novel type of phosphide: synthesis and X-ray crystal structure analysis of (tBu3Si)3P4Li3

The tetraphosphides (tBu3Si)3P4M3 (M = Li, Na) and (tBu2PhSi)3P4Na3 have been synthesized in high yield from the reaction of 3 equivalents of the silanides tBu3SiM (M = Li, Na) and tBu2PhSiNa with P4 in benzene. (tBu3Si)3P4M3 (M = Li, Na) are transformed into the unsaturated triphosphides (tBu3Si)2P3M (M = Li, Na) and tBu3SiPM2 in tetrahydrofuran at ambient temperature.     

Synthesis of the Oviposition-Deterring Pheromone (ODP) in Rhagoletis cerasi L. Preliminary communication

For the assignment of the configuration at C(8) and C(15) of the natural oviposition-deterring pheromone 1 in Rhagoletis cerasi L., the four possible stereoisomers of 1 are synthesized. By condensing the C₆ building blocks (5R)- 4 and (5S)- 4 with the boron enolates of the C₁₀ building blocks (4S)- 13 and (4R)- 13 , followed by decarboxylative dehydration, all stereoisomers of 16 are available (Scheme 5). Glucosylation of 16 followed by formation of the taurin amide gives, after deprotection, the four stereoisomers (8R,15S)- 1 , (8R,15R)- 1 , (8R,15S) -1 , and (8S,15S)- 1 (Scheme 6).     

Unprecedented, fully recyclable, solid-supported reagent for the kinetic resolution of racemic amines through enantioselective N-acetylation

The high-yielding synthesis and application of the first polymer supported reagent for the kinetic resolution (KR) of amines through enantioselective acetylation is described; this new supported chiral reagent allows the KR of primary amines with excellent selectivities at room temperature; moreover, this supported approach is highly efficient as the Merrifield-supported chiral scaffold can be quantitatively recovered and recycled.     

Solvation of uranyl(II), europium(III) and europium(II) cations in "basic" room-temperature ionic liquids: a theoretical study

We report a molecular dynamics study of the solvation of UO2(2+), Eu3+ and Eu2+ ions in two "basic" (Lewis acidity) room-temperature ionic liquids (IL) composed of the 1-ethyl-3-methylimidazolium cation (EMI+) and a mixture of AlCl4- and Cl- anions, in which the Cl-/AlCl4- ratio is about 1 and 3, respectively. The study reveals the importance of the [UO2Cl4]2- species, which spontaneously form during most simulations, and that the first solvation shell of europium is filled with Cl- and AlCl4- ions embedded in a cationic EMI+ shell. The stability of the [UO2Cl4]2- and [Eu(III)Cl6]3- complexes is supported by quantum mechanical calculations, according to which the uranyl and europium cations intrinsically prefer Cl- to the AlCl4- ion. In the gas phase, however, [Eu(III)Cl6]3- and [Eu(II)Cl6]4- complexes are predicted to be metastable and to lose two to three Cl- ions. This contrasts with the results of simulations of complexes in ILs, in which the "solvation" of the europium complexes increases with the number of coordinated chlorides, leading to an equilibrium between different chloro species. The behavior of the hydrated [Eu(OH2)8]3+ complex is considered in the basic liquids; the complex exchanges H2O molecules with Cl- ions to form mixed [EuCl3(OH2)4] and [EuCl4(OH2)3]- complexes. The results of the simulations allow us to better understand the microscopic nature and solvation of lanthanide and actinide complexes in "basic" ionic liquids.     

Simultaneous separation of flavanone glycosides and polymethoxylated flavones in citrus juices using liquid chromatography

We present a simultaneous liquid chromatographic method for the separation of two flavonoid compound families, flavanone glycosides (FGs) and polymethoxylated flavones (PMFs), which are usually found in citrus fruit species and varieties. This technique permits the quantitation of six FGs (narirutin, naringin, hesperidin, neohesperidin, didymin, poncirin) and six PMFs (sinensetin, hexamethoxyflavone, nobiletin, scutellarein, heptamethoxyflavone and tangeretin). This technique, to be used to characterize a citrus juice by its polyphenolic profile, has been applied to the determination of flavonoid compounds in grapefruit- and orange juice. Differentiation of orange juice varieties and mixtures containing tangor juice using polyphenolic profiles and flavonoid content has been achieved.     

RECOVERY FROM DAMAGE INDUCED BY ACRIDINE PLUS NEAR-ULTRAVIOLET LIGHT IN ESCHERICHIA COLI

Abstract— Escherichia coli cells treated with sublethal doses of acridine plus near-UV light exhibit an effective split-dose recovery response that requires an incubation period of about 30–45 min. Studies of the metabolic requirements for split-dose recovery revealed the following: (a) DNA synthesis is not required for split-dose recovery; (b) inhibition of electron transport or protein synthesis reduces the efficiency of split-dose recovery by about one-half; (c) inhibition of phospholipid synthesis or cell wall synthesis completely eliminates the split-dose recovery response. These results suggest an involvement of membrane repair mechanisms in response to damage by acridine plus near-UV light. Additional evidence for such a process was provided by more direct assays for membrane recovery. It was found that cells treated with sublethal doses of acridine plus near-UV light are sensitive to low concentrations of detergents, and lose that sensitivity upon incubation. Likewise, treated cells are susceptible to lethal osmotic shock, but can recover from this susceptibility if incubated after treatment but prior to exposure to low osmotic conditions. Based on accumulating evidence, we propose that E. coli cells are capable of repairing membrane damage resulting from exposure to acridine plus near-UV light.     

Substituierte 2-(Thiazol-4-yl)-phenole als Liganden und potentielle Extraktionsmittel für Kupfer(II)

Substituted 2-(Thiazol-4-yl)-phenols as Ligands and Potential Extractants for Copper (II) Substituted 2-(thiazol-4-yl)-phenols are obtained by the HANTZSCH synthesis. Their solubility in toluene is higher than in n-octane depending on the position, the chain length, and the polarity of the substituents. From alcoholic solutions complexes of the type CuL₂ⁿ are precipitated. According to the substituents their structure is distorted octahedral (CuL₂², CuL₂³) or distorted tetrahedral (CuL₂⁸, CuL₂⁹). The new complexes are nearly insoluble in toluene and aliphatic hydrocarbons, but CuL₂⁸ and CuL₂⁹ are soluble in chloroform. Therefore copper(II) may be extracted by HL⁸ and HL⁹ using chloroform as a diluent.