α BB Resonance in the ν8 Band of Borazine –10B

The high-resolution FTIR spectrum of the fundamental ₈ of borazine ¹⁰B₃ ¹⁴N₃ ¹H₆ was reanalyzed taking into account the ^BB resonance with the combination band (₁₀ + ₁₇). A parameter set for the states ₈ = 1 and ₁₀ = ₁₇ = 1, respectively, is given, reproducing the observed spectrum at least up to J = 30 with experimental accuracy.     

Analysis of the Temperature and Composition Dependence of Viscosimetric Properties of 2-Butanone <Emphasis Type="Bold">+</Emphasis> 2-Butanol Solvent Mixtures

Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0x_i1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(x_i), and =(T, x_i). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*^E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.     

Simple Estimations of Dynamic Polarizabilities and Dispersion Coefficients Using the Spectral Moment Method

A modification of the spectral moment technique is suggested to calculate the frequency-dependent polarizabilities (i ) and ( ) and the corresponding dispersion constants. Unlike the previous schemes, this method uses the spectral moments S _q with positive values of q. Both variational and nonvariational methods are tested. An effective nonvariational procedure is worked out which isolates a regular (odd) component from the Brown–Rebane functional for (i ). Fast convergence to exact values is achieved by using a suitable renormalization of the electron transition pseudospectrum. The method is illustrated by the semiempirical and ab initio calculations of molecular systems of various classes.     

Energetics of intramolecular hydrogen bonds and conformations of ω-diphenylphosphoryl- and ω-diphenylthiophosphoryl-substituted aliphatic alcohol molecules

A series of conformationally heterogeneous and energetically multilevel -diphenylphosphoryl- and -diphenylthiophosphoryl-substituted aliphatic alcohols, whose molecules are capable of five-, six-, and seven-membered ring closure due to the OH...O=P or OH...S=P intramolecular hydrogen bond (IHB), was studied by IR spectroscopy and molecular mechanics. The data obtained confirm the previous assumption that the energy of IHB (E _IHB) differs substantially from the difference of enthalpies of conformers with and without IHB (–H ), which is experimentally determined by the temperature dependence of the intensity of IR (OH) absorption bands. The measured –H values can be positive, zero, or negative at significant IHB effects, i.e., at high (OH) and E _IHB values.     

Synthesis of 4-Benzylsulfonyl-5-polyfluoroalkyl-ν-triazoles from 1,1-Dihydropolyfluoroalkyl Benzyl Sulfones

The reaction of 1,1-dihydropolyfluoroalkyl benzyl sulfones with sodium azide or trimethylsilyl azide in the presence of tertiary amines gives ammonium salts of 4-benzylsulfonyl-5-polyfluoroalkyl--triazoles. The proposed reaction scheme includes the participation of catalytic amounts of azide ion in the cyclization of the formed intermediate vinyl azides to triazoles. X-ray analysis of 1,4-diazabicyclo[2.2.2]octane salt of 4-benzylsulfonyl-5-(-H-hexafluoropropyl)--triazole has been carried out.     

Concerning the enantiomerization barrier of hypericin

Summary The Syntheses of -(R)-menthyl and ,-bis-(R)-menthyl derivatives2 and3 of hypericin were achieved, and the corresponding diastereomers could be separated. The equilibria between the respective diastereomers are slightly displaced in favor of the chromatographically faster moving ones. Kinetic measurements on these easily equilibrating diastereomers of2 and3 provided anArrhenius activation energy for the interconversion barrier between the two propeller conformers of 83 and 89 kJ/mol. It could be shown that the -menthyl residues are of minor relevance to the height of this barrier, as is also the case for thebay hydroxyl ionization and quinone tautomerization equilibria. It was thus concluded that the intrinsic barrier for the propeller conformer enantiomerization of hypericin is in the order of 80 kJ/mol. These results are in accord with those obtained from semiempirical calculations.

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Zur Enantiomerisierungsbarriere von Hypericin

Zusammenfassung Nach Synthese der -(R)-Menthyl- und ,-bis-(R)-Menthylderivate2 und3 des Hypericins konnten die entsprechenden Diastereomerenpaare getrennt werden. Die Gleichgewichte sind etwas zugunsten der chromatographisch rascher wandernden Diastereomeren verschoben. Kinetische Messungen an diesen leicht äquilibrierenden Diastereomeren von2 und3 führten zu einerArrheniusschen Aktivierungsenergie für die Interkonversionsbarriere zwischen den beiden Propellerkonformeren von 83 und 89 kJ/mol. Es konnte gezeigt werden, daß die -Menthylreste für die Höhe dieser Barriere nur geringfügige Bedeutung haben, ebenso wie dasbay-Hydroxyl-Ionisierungsgleichgewicht und das Tautomeriegleichgewicht. Daraus wurde geschlossen, daß die intrinsische Barriere für die Enantiomerisierung der beiden Hypericinpropellerkonformeren in der Größenordung von 80 kJ/mol liegt. Dieses Resultat stimmt mit den Ergebnissen semiempirischer Rechnungen überein.

     

On the synthesis of ω-appended hypericin derivatives

Summary A method for the preparation ofbis--appended hypericin derivatives bearingn-octyl,n-hexadecyl, and 2-(2-(2-hydroxyethoxy)-ethoxy)-ethoxymethyl substituents was developed. The key step — the synthesis of appropriately -substituted emodin derivatives — was achieved by solvolyzing 3-bromomethyl-1,6,8-triacetyloxy-anthracene-9,10-dione (-bromo triacetylemodin) in an appropriate alcohol in the presence of silver perchlorate. The correspondingbis--substituted hypericins were then prepared conventionally by dimerizing the -substituted emodin anthrones. The latter were prepared by reduction of the -appended emodins.

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Zur Synthese von -substituierten Hypericinderivaten

Zusammenfassung Eine Methode zur Darstellung vonbis--substituierten Hypericinderivaten wurde entwickelt. Der Schlüsselschritt — die Synthese der entsprechenden Emodinderivate — wurde durch die Solvolyse von 3-Bromomethyl-1,6,8-triacetyloxyanthracen-9,10-dion (-Bromtriacetylemodin) im entsprechenden Alkohol in Gegenwart von Silberperchlorat ermöglicht. Die entsprechendenbis--substituierten Hypericinderivate wurden auf konventionelle Weise durch Dimerisierung der -substituierten Emodinanthrone dargestellt. Letztere erhielt man durch Reduktion der -substituierten Emodine.

     

Third-Order Nonlinear Optical Response of a New PVA Composite with PbS Nanocrystals

High third-order nonlinear optical susceptibility (⁽³⁾(;, –,)=3.4·10 ^–16 m²/V²) in the visible spectral range may be achieved in PVA composites with narrow-gap PbS semiconductor nanocrystals with a large exciton diameter.     

New α,ω-diamido and α,ω-diamino mono-and bi-bridged acridine dimers

A novel set of dimers derived from 9-amino acridine was prepared and characterized by¹H and¹³CNMR. These derivatives are bridged at several different positions of the heterocyclic moieties, by the way of ,-diamido or ,-diamino side-chains. Additionally the preparation of some bi-bridged compounds was achieved.

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Neue ,-Dimaido- und ,-Diamino-Mono- und Bi-überbrückte Acridin-Dimere

Zusammenfassung Es wurde eine neue Reihe von Dimeren des 9-Aminoacridins hergestellt und mittels¹H und¹³C-NMR charakterisiert. Diese Derivate sind an verschiedenen Positionen des Heterocyclus mit ,-Diamido- oder ,-Diamino-Seitenketten überbrückt. Zusätzlich wurden auch einige zweifachüberbrückte Verbindungen hergestellt.

     

Berechnung des zeitabhängigen dielektrischen Faktors und der zeitabhängigen spezifischen Leitfähigkeit relaxationsbehafteter Dielektrika aus frequenzabhängigen Messungen

Zusammenfassung Es werden Näherungen mitgeteilt, mit deren Hilfe die spezifische zeitabhängige Leitfähigkeit von relaxationsbehafteten Dielektrika aus der Verlustkomponentet" () des komplexen dynamischen dielektrischen Faktors ^*() berechnet werden kann. Die Näherungen sind wesentlich genauer als die bekannte Hamon-Näherung. Gegenüber der exakten Fouriertransformation von haben sie den Vorteil, daß einen nur in einem beschränkten Frequenzbereich um den Wert =1/t bekannt sein muß und daß sie sehr viel einfacher zu handhaben sind. Es handelt sich bei dieser Näherung um Linearkombinationen von-Werten, die an den Stützstellen= 1/2l _t , 1/2^-1 t,...2⁺¹ t l = 2,3,4 zu nehmen sind. Fürl = 4 beträgt der höchstmögliche Fehler der Näherung 0,8% des Wertes von ₀ () mit =1/t. ₀ steht für die dielektrische Feldkonstante.Desgleichen werden Näherungen abgeleitet, die es ermöglichen, den zeitabhängigen dielektrischen Faktor(t) aus der Speicherkomponente() von ^* () auf einfache Weise sehr genau zu ermitteln. Auch diese Näherungen stellen Linearbeziehungen von() an den Stützstellen = 2 ^q/t , 2^q–1/t,...., 1/2 ^r t,... dar. Dabei treten die-Werte an den mit 1/2 ^r abfallenden Stützstellen als Differenzen [()=1/2 ^r+1 t)- ( = 1/2 ^r t)] in einer unendlichen Summe auf, die sehr schnell konvergiert und im allgemeinen fürr = 3 abgebrochen werden kann. Es werden Näherungen fürq = 1, 2,3 angegeben.

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Summary Approximative formulas are derived, which allow to calculate the transient currenti(t) from the loss component() of the dielectric permittivity ^*(). These formulas are of great numerical simplicity and above all they do not require the knowledge of over the whole frequency range as the exact Fourier transformation formula does. The relations given consist of linear combinations of () taken at=1/2 t, 1/2 ^l–1t ,..., 2 ^l+1t forl = 2,3 or 4. The error bounds of the equation withl = 4 are less than 0,8% relative to ₀ (), = 1/t. ₀ is the dielectric constant of the vacuum.In a similar way the time-dependent dielectric factor(t) can be calculated from the storage component () of ^* (). It has been shown that(t) can be represented by a sum of ( = 1/t) and difference terms [( = 1/2 ^j+1 t) –( = 1/2jt)],j =q,q + 1, .... In general these difference terms become negligibly small forj > 3. There are equations given forq = –1, –2 and –3.

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Mit 2 Tabellen     

Synthesis of 2-amino-3-(ω-aminoalkyl)indoles

2-Amino-3-(-phthalimidoalkyl)indoles have been obtained by the rearrangement of -phthalimido acid -phenylhydrazides under the action of POCl₃. The possibility has been studied of eliminating the phthalyl protective group from these compounds and a convenient method has been developed for obtaining 2-amino-3-(-aminoalkyl)indole dihydrochlorides. The behavior of the 2-amino-3-(-phthalimidoalkyl) indoles in alkylation reactions has been investigated.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 484–488, April, 1980.     

Interpretation of AC Conductivity of Lightly Doped Conducting Polymers in Terms of Hopping Conduction

The ac conduction of most disordered materials shows a regime of constant dc conductivity (0) at low frequencies and a crossover to a frequency-dependent regime of the type A ^s at high frequencies. We discuss the physical origin of this behavior and the interpretation of the onset frequency of excess ac conduction, _c , in terms of models for hopping conduction of polaronic carriers in a disordered medium. We emphasize the central role of the critical hopping rate in the percolation lattice for determining both (0) and _c . We show the behavior of () for lightly doped polypyrrole samples at different stages of doping, and we discuss the significance of frequency dispersion effects for electrochemical measurements.     

Schrödinger Equation Solutions for the Central Field Power Potential Energy II. V(r) = −V 0(r/a 0)2ν−2, 0 ≤ ν ≤ 1, the Bound States

The bound states of the generalized Schrödinger equation system with radial potential energy V(r) = –V ₀(r/a ₀)^2–2, 0 1, are described. The solutions of the differential equation are related to the functions for the bound state problem with 1. The Green's function is constructed as well as its first iteration, the traces of both functions are calculated, and an upper and lower bound for the ground state is established. A WKB-like approximate solution for the eigenvalues and eigenfunctions is derived.     

Phase separation of poly(γ-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

Solvent effects on the phase separation of poly(-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, ₂ ^* , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed ₂ ^* value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed ₂ ^* values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the ₂ ^* value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, the ₂ ^* is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.The author is grateful to Mr. K. Sano and Mr. M. Watanabe for their observation of the liquid crystal formation.     

Vibrational isotope effect of linear and planar molecules: Deuterated bromoethenes

Linear (planar) molecules A and B which are identical except for isotopic substitutions at the atomic sites are considered. Stretching (bending, out-of-plane) frequencies _k and normal modes _k of the isotopically perturbed molecule B are expressed in terms of stretching (bending, out-of-plane) frequencies _i and the corresponding normal modes _i of the unperturbed molecule A. Complete specification of the unperturbed normal modes is not required. All that is needed are stretching (bending, out-of-plane) amplitudes | _i of the normal modes _i at those sites that are affected by isotopic substitution. The rule which interlaces frequencies _k of molecule A with frequencies _i of molecule B is derived. Given two isotopic molecules A and B that differ by a single isotopic substitution at site , the inversion relation is derived. This relation expresses unperturbed stretching (bending, out-of-plane) amplitudes at the site in terms of stretching (bending, out-of-plane) frequencies of molecules A and B . As an example, out-of-plane vibrations of deuterated bromoethene were considered. In the simplest method 12 out-of-plane frequencies of four polydeuterated bromoethenes were calculated from 12 out-of-plane frequencies of bromoethene and three monodeuterated bromoethenes. Standard deviation of thus calculated frequencies from experimental frequencies is =2.74 cm^–1. In another method, 15 out-of-plane frequencies of four polydeuterated bromoethenes and selected monodeuterated bromoethene are calculated from 9 out-of-plane frequencies of bromoethene and the remaining two monodeuterated bromoethenes. Depending on which monodeuterated bromoethene is selected (1-, cis- or trans-), standard deviation of thus obtained frequencies from experimental frequencies is 1=2.84 cm^–1, c=2.96 cm^–1 and t=2.72 cm^–1.     

Reaction ofα,α-dichloro-ω-bromoalkanes andα,α-dichloro-ω-bromoalkenes with benzylmagnesium and allylmagnesium halides

Conclusions The,-dichloro--bromoalkanes and,-dichloro--bromoalkenes react with the benzyl- and allylmagnesium halides in tetrahydrofuran solution to give,-dichloroalkyl(alkenyl)benzenes,,-dichloroalkadienes in high yields. For all practical purposes the reactions do not go in ether.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 886–890, April, 1972.     

Effect of polar solvents on νpo in infrared spectra and chemical shifts in31p NMR spectra of phosphoryl compounds

Conclusions We measured the _po frequencies in the IR spectra of two phosphoryl compounds in a number of dipole solvents and found that a linear relation exists between the _po shifts and the changes in ³¹P chemical shifts of triethylphosphine oxide in the corresponding solvents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1191–1193, May, 1977.     

Synthesis of modified amino acids containing nucleic acid purine bases

The reaction of hydrazides of adenylyl- or hypoxanthinyl-9-alkylcarboxylic acids with sodium nitrite in acid media gives reactive azides of purinyl-9-alkylcarboxylic acids which condense with ()-aminocarboxylic and ,-diaminocarboxylic acids to give N(N)-(adenylyl-9-alkanoyl) aminocarboxylic, N-(adenylyl-9-)- and N-(hypoxanthinyl-9-alkanoyl)-,-diaminocarboxylic acids. The deamination of N-(adenyl-yl-9-alkanoyl)aminocarboxylic acids gives N-(hypoxanthinyl-9-alkanoyl)aminocarboxylic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 126–130, January, 1985.     

Dynamic shear modulus in the splitting region of poly(alkyl methacrylates)

A systematic study of the dynamic shear modulusG ^*=G+G in three poly(alkyl methacrylates) (PEMA, PnPMA, PnBMA) at frequencies between 0.001 and 500 rad/s is presented. As the splitting frequencies _s are low, aging effects can be observed in the splitting region. There is a systematic shift of the splitting frequency _s to lower values with increasing length of the alkyl side group. In PnBMA a separate shear appearance is observed about two frequency decades below the local mode . This is discussed in terms of the concept of minimal cooperativity. Aging effects are: Shift of the maximum loss frequency to lower values, peak sharpening of the relaxation, and intensity changes of and . These effects are discussed in terms of the sequential aging concept. Aging leads to a pronounced bending of the traces upwards from the equilibrium line in the Arrhenius diagram. These non-equilibrium phenomena are promoted by the small slope m=d(log )/dT of the trace in the splitting region.Dedicated to Prof. E. W. Fischer at the occasion of his 65th Birthday Lieber Herr Fischer, die Hallenser Polymerphysiker danken Ihnen aufrichtig für die warmherzige und effektive Förderung der Polymerwissenschaften im Raum Halle-Merseburg.