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131.
Prof. Dr. O. Hromatka D. Binder K. Eichinger 《Monatshefte für Chemie / Chemical Monthly》1974,105(1):123-126
The synthesis of 5-(o-trifluoromethylphenyl)-1H-thieno-[3,4-e]1,4-diazepin-2(3H)-one (7) and its nitration and chlorination in pos. 8 are described. 相似文献
132.
Prof. Dr. Enrique J. Baran 《Monatshefte für Chemie / Chemical Monthly》1975,106(1):121-126
Mean amplitudes of vibration of a series of tetrahedralXY 4 molecules and ions (hydrides, halides, oxides and oxoanions) have been calculated using the “Method of the Characteristic Vibrations” ofA. Müller. The results indicate that this method leads to very good values for most of the investigated species, and especially in the cases of highM X/MY mass ratio. 相似文献
133.
Farren C FitzGerald S Beeby A Bryce MR 《Chemical communications (Cambridge, England)》2002,(6):572-573
An initial photophysical study of a tetra-solketal-substituted zinc phthalocyanine is reported; at low temperature this compound exhibits very strong aggregation, and a new red shifted emission peak is observed, lambda max approximately 750 nm, attributed to a fluorescent phthalocyanine dimer. 相似文献
134.
Meier H Gerold J Kolshorn H Mühling B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(2):360-370
Four OPV series 1-4 (a-d) with a terminal dialkylamino group as electron donor were prepared by Wittig-Horner reactions. To study the influence of the push-pull effect on the long-wavelength absorption, three of the four series contained terminal acceptor groups (CN, CHO, NO(2)). The length of the chromophores strongly affects the intramolecular charge transfer (ICT)-an effect which superimposes upon the extension of the conjugation. Increasing numbers n of repeat units cause an overall bathochromic shift for the purely donor-substituted series 1 a-4 a and the series 1 b-4 b with CN as weak acceptor. The two effects annihilate each other in the series 1 c-4 c with terminal CHO groups, so that the absorption maxima are almost independent of the length of the chromophore. A hypsochromic shift is observed for the series 1 d-4 d, which contains the strong acceptor group NO(2). This anomaly disappears on protonation of the dialkylamino group because the push-pull effect disappears in the ammonium salts. The results can be explained by semiempirical quantum mechanics (AM1, INDO/S). The HOMO-LUMO transition, which is mainly responsible for the ICT, becomes less important in the electron transitions S(0)-->S(1) when the distance between donor and acceptor is increased. The commonly used VB model, which contains an electroneutral and a zwitterionic resonance structure, is contrasted with a MO model with dipole segments at both ends of the OPV chains. The latter model turned out to be more appropriate-at least for donor-acceptor-substituted OPVs with n >/= 2. 相似文献
135.
Doz. Dr. Friedrich Höfler Ernst Brandstätter 《Monatshefte für Chemie / Chemical Monthly》1975,106(4):893-904
The reactions of Ge2(C6H5)6 with HCl and HBr lead in nearly quantitative yields to the 1,1,2,2-tetrahalo derivatives Cl2(C6H5)GeGe(C6H5)Cl2 (I) and Br2(C6H5)GeGe(C6H5)Br2 (II), resp. The Si?Ge bond of (C6H5)3SiGe(C6H5)3 is cleaved under the conditions of hydrohalogenation. The vibrational spectra of Ge2Br6, Ge2(C6H5)6, I, and II are reported. The influence of vibrational coupling on ν GeGe in these compounds is discussed in detail, including vibrational calculations. 相似文献
136.
A critical comparison of approximation methods and models for equilibrium properties of low-barrier hydrogen bonds 总被引:1,自引:0,他引:1
MacDonald DA Eppard GE Halkides CJ Messina M 《Journal of chemical information and computer sciences》2002,42(6):1390-1397
Recent experimental evidence has led to the conclusion that short, strong hydrogen bonds can stabilize transition states of enzyme catalyzed biochemical reactions. Evidence for such hydrogen bonds is the low value of the isotopic fractionation factor, phi, which is defined as the equilibrium constant for the generic reaction, R-H + DOH <--> R-D + HOH, where H is the hydrogen atom participating in the low-barrier hydrogen bond in a molecule R-H. In this work we assess two approximation methods for computing the isotopic fractionation factors for single and multidimensional systems containing a low-barrier hydrogen bond. These methods are WKB and an approach that corrects the classical partition function via a quantum correction factor. We find that the latter approach is universally accurate and applicable in both single and multidimensional systems containing a low-barrier hydrogen bond. We also assess two different models for the coupling of a molecule's low-barrier hydrogen bond to other degrees of freedom, both internal and external to the molecule, and show that each leads to a lowering of the fractionation factor. 相似文献
137.
H. Meier E. Zimmerhackl W. Albrecht D. Bösche W. Hecker P. Menge A. Ruckdeschel E. Unger G. Zeitler 《Mikrochimica acta》1970,58(3):553-563
Zusammenfassung Die hochspannungselektrophoretische Wanderung der Halogenokomplexe der Platinmetalle und einer Reihe weiterer anorganischer Ionen wird mit Nitrilotriessigsäure und Äthylendiamintetraessigsäure als Elektrolyt in Abhängigkeit von verschiedenen Versuchsparametern (Elektrolytkonzentration,ph-Wert und Substanzmenge) untersucht. Die Wanderungsgeschwindigkeiten der verschiedenen Metallionen bzw.-komplexe zeigen charakteristische Abstufungen, die sich mit den für die hochspannungselektrophoretische Wanderung gültigen Gesetzmäßigkeiten erklären lassen. Beispielsweise beobachtet man eine Abnahme der Beweglichkeit bei Ersatz von Chlorid- durch Bromidionen (Masseneinfluß), Auswirkungen der vomph bzw. der Elektrolytkonzentration abhängigen unterschiedlichen Komplexierungen zwei- und dreiwertiger Ionen, Einflüsse der auf Hydrolyse zurückgehenden Änderungen der Ligandenzusammensetzung sowie Unterschiede der Wanderungsgeschwindigkeiten als Folge der Komplexierung mit NTE oder AeDTE.Durch die unter bestimmten Bedingungen erreichbare Abstufung der Beweglichkeiten können verschiedene Gemische, unter anderem auch die Chlorokomplexe der meisten Platinmetalle in der Reihenfolge Ir > Os Pt > Rh Pd > Ru (> Rh), getrennt werden. NTE ist dabei für Trennungen besser als AeDTE geeignet.
The high tension electrophoretic separation of inorganic ions with special reference to the platinum metals. I
Summary The high tension electrophoretic migration of the halogeno complexes of the platinum metals and several other inorganic ions was investigated with nitrilotriacetic acid and ethylenediaminetetraacetic acid as electrolytes in relation to the various experimental parameters (electrolyte concentration,ph-value, and amount of substance). The migration velocities of the various metal ions or complexes exhibit characteristic gradations that may be explained on the basis of the regularities that are valid for the high tension electrophoretic migration. Instances are: a decrease was observed in the mobility when chloride was replaced by bromide ions (mass effect), influence of different complexing of di- and trivalent ions that are related to changes in theph or electrolyte concentration, or influences of the changes due to hydrolysis in the composition of the ligands or alterations in the migration rates resulting from complexing with nitrolotriacetic acid or EDTA.The gradation of the mobility obtained under certain conditions are employed as the basis of a procedure for separating various mixtures, including also the chloro complexes of most of the platinum metals in the succession Ir > Os Pt > Rh Pd > Ru (> Rh). It has been found that NTE is better for separations than EDTA.相似文献
138.
It is shown that azulenium cations in the first electronically excited state S1 are stronger acids than in the ground state S0. Their apparent pK″*, obtained from the H0-dependence of the quenching of the azulenium cation S1 → S0 fluorescence does not correspond to a true acid-base equilibrium in the electronically excited state S1. The pK″* values are kinetically controlled, the rate of reprotonation of azulene in the S1 state being too low to compete with the internal conversion to S0. 相似文献
139.
Prof. Dr. Edmund Hlawka 《Monatshefte für Mathematik》1980,89(1):19-44
A new proof of a theorem of W. Neiss is given that the rays of the Quadratwurzelschnecke are uniformly distributed mod 2 . The exact order of the discrepancy of the sequence is determined. Multidimensional generalizations of this sequence are also considered. It is shown that the Quadratwurzelschnecke is something like a roulette.
Mit 2 Abbildungen
Herrn Prof. R. M. Redheffer in Freundschaft zum 60. Geburtstag gewidmet 相似文献
Mit 2 Abbildungen
Herrn Prof. R. M. Redheffer in Freundschaft zum 60. Geburtstag gewidmet 相似文献
140.
Dr. Lisa Hefendehl-Hebeker 《Monatshefte für Mathematik》1980,90(3):219-228
Motivated by an investigation ofKuz'min [2], in this note we introduce a topology on the set
of nonassociative algebras of a fixed dimensionr< over a local fieldF. We obtain a space, which is notT
1. If the trivial algebra
is removed, the remaining subspace is quasicompact. The space is homeomoprhic to the group of square classes ofF
*; forr3 the space is notT
1. The set of division algebras is open in. 相似文献