Distinction of tris(diimine)ruthenium(II) enantiomers chiral by virtue of helical chirality: temperature-dependent deuterium NMR spectroscopy in partially oriented phases

2H NMR spectra of perdeuterated tris(diimine)ruthenium(II) complexes have been recorded in lyotropic liquid crystalline phase formed by the chiral polypeptide, poly-gamma-benzyl-L-glutamate (PBLG) and co-solvents. It is demonstrated that the left- and right-rotation isomers of these octahedral metal complexes with D3 symmetry can be distinguished. The effects of temperature and ligand size on spectral resolution were also studied. Although in the case of free bipyridine ligands excellent optical resolution could be obtained at room temperature in the complexes studied, the increase in ligand size has a detrimental effect on the resolution. This can be compensated to some extent by elevating the sample temperature and decreasing the deuterium relaxation rates, but the available temperature range and therefore the applicability of the technique are limited.     

Investigation of acidic pharmaceuticals in river water and sediment by microwave-assisted extraction and gas chromatography–mass spectrometry

Investigations were performed along the Danube river at Budapest (Hungary) by collecting water and sediment samples simultaneously for 1 year in order to clarify the possible hazard of selected acidic pharmaceuticals (ibuprofen, naproxen, ketoprofen, and diclofenac) on the water supply used for the production of drinking water by bank filtration. In the case of water samples, the sample preparation procedure included solid phase extraction (SPE), meanwhile, in the case of sediment samples, microwave-assisted extraction (MAE) followed by dispersive matrix extraction (DME) for pre-cleaning as well as SPE for enrichment. The quantification was carried out using gas chromatography–mass spectrometry (GC–MS). The calculated recoveries were 97–99% (± 7%) for the water and 95–103% (± 12%) for the sediment samples. In the river water, ketoprofen concentration was always below the limit of quantification (LOQ) level; ibuprofen, naproxen and diclofenac could be quantified in the range of 8–50, 2–30, 7–90 ng/L. In sediments, only naproxen and diclofenac were found in the range of 2–20 and 5–38 ng/g, respectively. According to the obtained results, the concentration ratios of the two phases linearly depended on the total organic carbon content (TOC) of the sediments at each sampling date. The linear regressions were 0.925 and 0.946 for naproxen and diclofenac, respectively.     

Molecular structures of the digermanes Me2XGeGeXMe2 (X = Me, Cl, and H): an ab initio study combined with experimental investigation by Raman spectroscopy and gas electron diffraction

Ab initio calculations were carried out to investigate the potential-energy surface for internal rotation of the methylated digermanes hexamethyldigermane Me(3)GeGeMe(3) ( 1), dichlorotetramethyldigermane Me(2)ClGeGeClMe(2) ( 2), and tetramethyldigermane Me(2)HGeGeHMe(2) ( 3). Different basis sets [6-31+G(d), SDD, aug-cc-pVTZ] were employed at the DFT and MP2 levels of theory to optimize structures and to calculate energies and vibrational frequencies. For 1, one minimum representing a staggered structure was located on the potential-energy surface. For 2 and 3, antiperiplanar conformations with C 2 symmetry were found to be the global minima. Additionally, synclinal minima were located for 2 and 3 when certain basis sets were employed. Determination of structural parameters in the gas phase by gas electron diffraction confirmed the computed predictions for all three compounds. For 2 and 3, the ratios of antiperiplanar to synclinal conformer were detected to be 90:10 (328 K) and 72:28 (293 K), respectively, by gas electron diffraction. The experimentally determined GeGe bond lengths in 1, 2, and 3 in the gas phase are 241.4(1), 242.7(2) (averaged for antiperiplanar and synclinal), and 241.7(1) pm (equal for antiperiplanar and synclinal). Only averaged structures were observed, using Raman spectroscopy, for 2 and 3 because the wavenumber differences are small between conformers and there is only a small contribution from the second conformer in each case. For 2, the crystal structure was also determined by X-ray diffraction. An anticlinal structure (with Cl atoms eclipsing the C atoms) was found with a GeGe bond length of 242.1 pm.     

Growth mechanism and characterization of zinc oxide microcages

We report the growth mechanism and structural properties of micrometer sized ZnO cages which were synthesized directly from Zn vapor deposition and oxidation. The ZnO microcages exhibit a hexagonal or spherical shape with partly or completely open surfaces and hollow interiors. The growth process of the microcages includes the deposition of Zn polyhedral particles, top face breaking of the Zn particles and Zn sublimation, and subsequent reaction to ZnO. By controlling the various growth stages, we obtained information on the growth mechanism of the ZnO cages, which appears to be different from a mechanism reported previously. The chemical composition and crystalline structure were studied using energy dispersive X-ray spectroscopy and transmission electron microscopy, respectively. The room-temperature photoluminescence spectrum indicates a large quantity of oxygen-vacancy related defects within the wall of the ZnO cages.     

Preparation and Spectral Characterization of Sulphur-Containing Diarylazo Compounds

Abstract

By reaction of arylazo-substituted aryl halides with mercaptides, new arylazo-substituted arylsulfides are formed. These compounds are deeply coloured and exhibit an intense absorption band in the visible region, which can be reproduced quantitatively and interpreted satisfactorily by means of quantum chemical calculations in the framework of the PPP and LHM methods, respectively.     

Guest-induced conformation shift of p-sulphonatothiacalix[4]arene in the solid state and solution manipulated by [Zn(dipy)3]2+

The ¹H NMR and X-ray analysis data reveal the guest-induced cone → partial cone and cone → 1,2-alternate conformational shift in aqueous methanol solutions and solid state for a p-sulphonatothiacalix[4]arene-[Zn(dipy)₃]²⁺ host–guest system. The experimental data, together with DFT calculations, show that the guest-induced conformational shift of p-sulphonatothiacalix[4]arene is facilitated by the deprotonation of phenolic groups.     

Metal-metal bond or isolated metal centers? Interaction of Hg(CN)2 with square planar transition metal cyanides

Three adducts have been prepared from Hg(CN)(2) and square planar M(II)(CN)(4)(2)(-) transition metal cyanides (M = Pt, Pd, or Ni, with d(8) electron shell) as solids. The structure of the compounds K(2)PtHg(CN)(6).2H(2)O (1), Na(2)PdHg(CN)(6).2H(2)O (2), and K(2)NiHg(CN)(6).2H(2)O (3) have been studied by single-crystal X-ray diffraction, XPS, Raman spectroscopy, and luminescence spectroscopy in the solid state. The structure of K(2)PtHg(CN)(6).2H(2)O consists of one-dimensional wires. No CN(-) bridges occur between the heterometallic centers. The wires are strictly linear, and the Pt(II) and Hg(II) centers alternate. The distance d(Hg)(-)(Pt) is relatively short, 3.460 A. Time-resolved luminescence spectra indicate that Hg(CN)(2) units incorporated into the structure act as electron traps and shorten the lifetime of both the short-lived and longer-lived exited states in 1 compared to K(2)[Pt(CN)(4)].2H(2)O. The structures of Na(2)PdHg(CN)(6).2H(2)O and K(2)NiHg(CN)(6).2H(2)O can be considered as double salts; the lack of heterometallophilic interaction between the remote Hg(II) and Pd(II) atoms, d(Hg)(-)(Pd) = 4.92 A, and Hg(II) and Ni(II) atoms, d(Hg)(-)(Ni) = 4.61 A, is apparent. Electron binding energy values of the metallic centers measured by XPS show that there is no electron transfer between the metal ions in the three adducts. In solution, experimental findings clearly indicate the lack of metal-metal bond formation in all studied Hg(II)-CN(-)-M(II)(CN)(4)(2)(-) systems (M = Pt, Pd, or Ni).     

Mapping of Malus domestica allergens by 2-D electrophoresis and IgE-reactivity

The importance of apple allergens has been repeatedly emphasized, and their presence has been confirmed both in pollen and in fruits. In the present study, a combination of proteomic tools have been used to build a complete allergen map of apple. The water-soluble fraction of an apple extract was precipitated using a phenol-based procedure and separated by 2-DE. Initially four previously classified allergens, Mal d 1, Mal d 2, Mal d 3 and Mal d 4, could be identified in Western blots with polyclonal rabbit antibodies directed to the four respective allergens, and subsequently matched to the bands recognized by several patient sera. Further, all four known apple allergens were localized on a 2-DE map and they were matched with spots recognized by sera of patients with different allergic patterns. Moreover, a new, putative allergen could be identified using MS. We evaluated the influence of post-translational modifications and the immunoreactivity under different analytical conditions. The comparison of different visualization methods for 2-DE gels and blots revealed that even very low concentrations of the intact epitopes are detectable by IgEs of patients, and therefore might be sufficient to trigger allergic symptoms in sensitized individuals.