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81.
E. Lassner und R. Scharf 《Fresenius' Journal of Analytical Chemistry》1961,183(3):187-190
Zusammenfassung Die seinerzeit angegebene ÄDTA-Titration des Molybdäns wurde dahin geändert, daß bei der Rücktitration des ÄDTA-Überschusses mit Kupferlösung der PAN-Indicator durch den Metall-Fluorescenzindicator Calcein ersetzt wurde. Dadurch gelingt es, die Titration auch höherer Molybdänkonzentrationen ohne Beeinflussung des Indicatorumschlages durch die gelbe Eigenfarbe des Molybdän(V)-ÄDTA-Chelats durchzuführen. Bei Molybdänmengen zwischen 20 und 60 mg beträgt der relative Fehler der Bestimmung im Mittel 0,30%. 相似文献
82.
The genomic sequence of Bacillus subtilis, which is the best studied Gram-positive bacterium, enabled us to obtain a theoretical two-dimensional (2-D) map, demonstrating that about one-third of this proteome has a theoretical alkaline isoelectric point (pI). This represents an important part of the entire proteome, which is not detectable in conventional 2-D gels (pH range 4-7). Sequence analysis revealed that 91% of the ribosomal proteins and a high amount of theoretical membrane proteins should be localized in the alkaline pH range requiring different protein extraction procedures. In order to find the pH range which gives the best resolution results for the alkaline proteins of B. subtilis, immobilized pH gradients (IPGs) with different pH ranges (pH 6-10, 6-11, 4-12, 9-12, and 3-10) were tested and optimized for IPG 4-12. Here we present a version of a first alkaline master 2-D gel for B. subtilis, which is a further complement of the already existing master gel (pH 4-7) in the Sub2D database. Almost 150 spots could be detected and 41 proteins have already been identified. 相似文献
83.
Prodi A Chiorboli C Scandola F Iengo E Alessio E Dobrawa R Würthner F 《Journal of the American Chemical Society》2005,127(5):1454-1462
A new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)](2), where DPyPBI = N,N'-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP = 5,10,15,20-tetraphenylporphyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)](2) has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (tau = 5.6 ps) followed by charge recombination (tau = 270 ps). Upon excitation of the Ru(TPP)(CO) fragments, on the other hand, ultrafast (tau < 1 ps) intersystem crossing is followed by triplet energy transfer from the ruthenium porphyrin to the perylene bisimide dye (tau = 720 ps). The perylene-based triplet state decays to the ground state on a longer time scale (tau = 9.8 micros). The photophysics of this supramolecular array provides remarkable examples of (i) wavelength-dependent behavior (a small change in excitation wavelength causes a sharp switch from electron to energy transfer) and (ii) intramolecular sensitization (the triplet state of the perylene bisimide, inaccessible in the free dye, is efficiently populated in the array). 相似文献
84.
Ute Ch.?Rodewald Mar’yana?Lukachuk Rolf-Dieter?Hoffmann Rainer?P?ttgenEmail author 《Monatshefte für Chemie / Chemical Monthly》2005,136(12):1985-1991
Summary. The gadolinium–rhodium–indide Gd3Rh1.940(7)In4 was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd3Rh1.940(7)In4 adopts the hexagonal Lu3Co1.87In4 type, space group
, a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F2 values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium
atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from
to
, leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated
crystal had a composition Gd3Rh1.940(7)In4. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., [Rh1In26Gd3], [Rh2Gd6In23], and [In1Gd6In23]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium
atoms build up a three-dimensional [Rh1.940(7)In4] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd3Rh1.940(7)In4 is discussed on the basis of a group-subgroup scheme. 相似文献
85.
Martin Kirchner Walter Schnelle Frank R. Wagner Rüdiger Kniep Rainer Niewa 《无机化学与普通化学杂志》2005,631(8):1477-1486
Single phase powders of (A19N7)[In4]2 (A = Ca, Sr) and (Ca4N)[In2] were prepared by reaction of melt beads of the metallic components with nitrogen. The crystal structure of (Ca19N7)[In4]2 was refined based on neutron and X‐ray powder diffraction data. The crystal structure of (Sr19N7)[In4]2 was solved from the X‐ray powder pattern. The structure refinements in combination with results from chemical analyses ascertain the compositions. The compounds (A19N7)[In4]2 (A = Ca, Sr) are isotypes of (Ca19N7)[Ag4]2; (Ca19N7)[In4]2 is probably identical to the earlier reported (Ca18.5N7)[In4]2. The crystal structure of the isotypes (A19N7)[In4]2 (A = Ca, Sr; cubic, , Ca: a = 1471.65(3) pm; Sr: a = 1561.0(1) pm) contains isolated [In4] tetrahedra embedded in a framework of edge‐ and vertex‐sharing (A6N) octahedra. Six of these octahedra are condensed by edge‐sharing around one central A2+ ion to form “superoctahedra” (A19N6) which are connected three‐dimensionally via further octahedra by corner‐sharing. The crystal structure of (Ca4N)[In2] (tetragonal, I41/amd, a = 491.14(4) pm, c = 2907.7(3) pm) consists of alternating layers of perovskite type slabs of vertex‐sharing octahedra (Ca2Ca4/2N) and parallel arranged infinite zigzag chains equation/tex2gif-stack-1.gif[In2]. In the sense of Zintl‐type counting the compounds (A2+)19(N3?)7[(In2.125?)4]2 present an electron excess, (Ca2+)4(N3?)[(In2.5?)2] is electron deficient. Metallic properties are supported by electrical resistivity and magnetic susceptibility measurements. The analysis of the electronic structures gives evidence for the existence of homoatomic interactions In–In and significant heteroatomic metal–metal interactions Ca–In which favor the deviations of the title compounds from the (8 – N) rule. 相似文献
86.
Pamela M. St. John Rainer D. Beck Robert L. Whetten 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(1):226-228
We review the processes which have been observed from collisions between alkali-halide clusters and solid surfaces. Soft impact of nanocrystalline NanF n?1 + clusters against solid surfaces causes them to cleave along the lowest energy (100) plane. At higher collision energies (Ei>1 eV/atom), an evaporative cascade occurs which is characteristic of a transformation of the nanocrystal to a molten state. Efficient F? transfer from the cluster to the surface can occur for the larger clusters (>60 atoms) scattering from Si(111), in direct competition with the cleaving channel at low energies. In this regime, strong bonds can form between the F? and silicon surface. The reaction probability increases with cluster size indicating that an impact-initiated shock wave is needed to enhance the reactive process. 相似文献
87.
Vilmos Fülöp Alajos Kalman Rainer Beckert Jürgen Fabian 《Monatshefte für Chemie / Chemical Monthly》1989,120(6-7):561-569
Summary The action of bisimidochlorides of oxalic acid on dithiocarbamates produces 2-thioxo-3-aryl(alkyl)-4,5-diiminothiazolidines by cycloacylation. The molecular structure of 2-thioxo-3-(4-methoxyphenyl)-4,5-bis(phenylimino)-thiazolidine is confirmed by X-ray crystal structure analysis.
Zur Reaktion von Dithiocarbaminaten mit stickstoffhaltigen Derivaten der Oxalsäure
Zusammenfassung Bei der Einwirkung von Bisimidchloriden der Oxalsäure auf Dithiocarbaminate entstehen durch Cycloacylierung 2-Thioxo-3-aryl(alkyl)-4,5-diiminothiazolidine. Die Molekülstruktur von 2-Thioxo-3-(4-methoxyphenyl)-4,5-bis(phenylimino)thiazolidin wird durch Röntgenkristallstrukturanalyse bestätigt.相似文献
88.
Josef Scharf Karl Schlögl Michael Widhalm Johann Lex Werner Tückmantel Emanuel Vogel Franz Pertlik 《Monatshefte für Chemie / Chemical Monthly》1986,117(2):255-267
2,7-Dibromo-1,6-methano[10]anulene (3) and 2,9-Dibromo-syn-1,6:8,13-diimino[14]anulene (9) were quantitatively separated into their enantiomers by chromatography on triacetylcellulose (TAC) in ethanol. X-ray structure analysis (Bijvoet technique) established the chiralities (+)(R)-3 and (+)(S)-9 for the dextrorotatory enantiomers.Comparison of the CD spectra allowed the configurational assignment to further optically active [10] and [14] anulenes which were also accessible by chromatography onTAC. Conversion of (+)(R)-2-bromo-1,6-methano[10]anulene (2) into the corresponding methylester (–)-4 confirmed its previously proposed chirality (–)(R).2,7-Dibromo-1,6-oxido[10]anulene (7) and 2,9-dibromo-syn-diimino[14]anulene (9) are in contrast to the 2,9-dibromo-syn-dioxido[14]anulene (10) optically stable until 250°C. Consequently their inversion barriers are higher than 42 kcal (176 kJ) mol–1.The CD spectra of mono and disubstituted anulenes (with C1 and C2 symmetry, resp.) are compared: For the [10]anulenes theCotton effect around 330 nm seems to be specific for their configuration with a positive effect indicating (S)-chirality and vice versa. Some regularities concerning the chromatographic resolutions are discussed.
Stereochemie planar chialer Verbindungen, 10. Mitt.: Röntgenkristallstruktur und absolute Chiralität überbrückter [10]- und [14] Anulene
Zusammenfassung 2,7-Dibrom-1,6-methano[10]anulen (3) und 2,9-Dibrom-syn-1,6:8,13-diimino[14]anulen (9) wurden durch Chromatographie an Triacetylcellulose (TAC) in Ethanol quantitativ in ihre Enantiomeren getrennt. Röntgenstruktur-analyse (Bijvoet-Technik) bewies für die rechtsdrehenden Enantiomeren die Chiralität (+)(R)-3 bzw. (+)(S)-9.Ein Vergleich der CD-Spektren ermöglichte die Konfigurationszuordnung weiterer optisch aktiver [10]- und [14]Anulene, die gleichfalls durch Chromato-graphie anTAC erhalten worden waren. Umwandlung von (+)(R)-2-Brom-1,6-methano[10]anulen (2) in den entsprechenden Methylester (–)-4 bestätigte dessen schon früher vorgeschlagene Chiralität (–)(R).Dibrom-1,6-oxido[10]anulen (7) und Dibrom-diimino[14]anulen (9) sind im Gegensatz zum Dioxido[14]anulen (10) bis 250°C optisch stabil. Ihre Inver-sionsbarrieren liegen somit über 42 kcal (176kJ) mol–1.Die CD-Spektren von mono- und disubstituierten Anulenen (mit C1 bzw. C2-Symmetrie) werden verglichen: Für die [10]Anulene scheint derCottoneffekt um 330 nm konfigurationsspezifisch zu sein, wobei ein positiver Effekt (S)-Chiralität anzeigt — und vice versa. Einige Regelmäßigkeiten bezüglich der chromatographischen Enantiomerentrennung werden diskutiert.相似文献
89.
Rainer Domanig 《Monatshefte für Chemie / Chemical Monthly》1981,112(10):1195-1202
Starting with the chloromethyl compounds7 the new 2-azidomethyl-3-aryl-4-quinazolinones8 a-h were prepared, some of which have been reduced so far to the corresponding amines9 a, b, e, g by H2S in good yield. As a first example for the capability of the azides8 to undergo 1,3-dipolar cycloaddition the 2-quinazolinmethyl-1,2,3-triazol-4,5-dicarboxylicacid dimethylesters11 b, e, g were prepared by reacting8 with dimethylacetylenedicarboxylate (10).
1. Mitt.:Domanig R., Arch. Pharm., im Druck. 相似文献
90.
Benjamin Scharf 《Chemical physics letters》1983,96(1):89-92
Prominent progressions of non-totally symmetric modes may ensue in non-linear molecules in electronic transitions involving degenerate states in the absence of Jahn-Teller distortions. In the presence of Jahn-Teller interactions prominent non-Jahn-Teller progressions may result. 相似文献