Isolation,purification, and characterization of cyclomaltodecaose (ε-CD)

-Cyclodextrin (-CD) is a cyclic oligosaccharide, composed of ten -1,4-linked D-glucoses reported by Frenchet al. in 1965¹⁾, but has not been studied because of the difficulty in the preparation and purification of large-ring CDs composed of more than nine -1,4-linked D-glucose units. This report describes the purification and characterization of -CD. Furthermore, the crystal and molecular structure of -CD hydrate -CD 19H₂O) was elucidated by X-ray analysis.     

Determination of various deformation processes in impact-modified PMMA at strain rates up to 105%/min

The deformation processes in impact-modified PMMA, which deforms homogeneously, were determined by means of the stress/strain experiment (, ) with simultaneous lateral strain measurement (_lat) in a wide range of strain rates () up to 10⁵%/min (impact stress). The elastic, plastic cavitation and plastic shear processes were determined as a function of strain. Therefore we calculated the elastic strain ( _el), the elastic volume expansion ( _{vol el}), the cavitation strain ( _cav), which is identical with the plastic volume expansion ( _{vol pl}), the shear strain ( _sh) and the energy densities (W_el, W_cav, W_sh) related to these three processes.For strains of 3 % onward it was found that plastic shear processes and plastic cavitation processes are responsible for a partial loss of elastically stored energy. Both plastic processes turn out to be mostly anelastic deformations, their amount depending strongly on the strain rate. The contributions of the processes to the total deformation of the unmodified PMMA in its strain range are similar to those of the impact-modified PMMA, and the high impact strength is caused by a shift of the catastrophic rupture to very high strains.     

The relative permittivity of 1,2-dimethoxyethane and N,N-dimethylformamide mixtures from −10 to 40°C

Binary solutions of N,N-dimethylformamide and 1,2-dimethoxyethane have been investigated by means of dielectric measurements at temperatures ranging from –10 to +40°C, and for nine mixtures covering the whole miscibility field expressed by the mole fraction of one component (0X₁1). The experimental data were used to study the dependence of on T and X₁, of the type = (T), = (X₁), and = (T,X₁). Further, the excess mixing function _E has been evaluated in order to identify particular patterns of interaction between unlike molecules and any other factor that could modify such patterns. The minimum in the _E vs. composition plots suggests the formation of an adduct of stoichiometric ratio DMFDME=11 at all the investigated temperatures.     

Synthesis of substituted lysine-containing oligopeptides

Conclusions Oligopeptides containing lysine and alanine and having the following sequences were obtained: BOC-[(N-Cb)-Lys]₆OCH₃, BOC-[(N-Cb)-Lys]₈OCH₃, BOC-Ala-[(N-Cb)-Lys]₄-Ala-OCH₃, and BOC-Ala-[(N-Cb)-Lys]₆-Ala-OCH₃.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1858–1860, August, 1972.     

The electronic spectrum of acrylonitrile

The vapor absorption spectrum of acrylonitrile CH₂CHCN has been measured in the vacuum ultraviolet region. In addition, an all-valence-electron molecular orbital calculation has been used to calculate the electronic structure and spectrum of the molecule. On the basis of the MO calculation, as well as a vibrational analysis of the observed spectrum, several electronic transitions are assigned. The lowest energy absorption band (2107Å, = 150) is assigned as an n ^* transition. Absorption bands at 2030Å (=1600), 1725Å ( = 2100), and 1570Å ( = 1920) are assigned as 0–0 bands associated with transitions that are, respectively, ^*,^*, and ^* in character.

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Zusammenfassung Das UV-Absorptionsspektrum von dampfförmigen Acrylnitril wurde gemessen und eine CNDO/2-Rechnung für die Elektronenstruktur durchgeführt. Auf dieser Basis konnten unter Zuhilfenahme der Analyse der Schwingungsstruktur im beobachteten Spektrum mehrere Banden zugeordnet werden: die 2107-Å-Bande ( = 150) einem n^*-Übergang, die drei Banden bei 2030Å ( = 1600), 1725Å ( = 2100) und 1570 Å ( = 1920)0-0-Übergängen von ^*-, ^*- bzw. ^*-Banden.

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Résumé Mesure du spectre d'absorption en phase vapeur de l'acrilonitrile CH₂CHCN dans la région de l'ultraviolet. Par ailleurs, la structure électronique et le spectre de la molécule ont été calculés à l'aide d'une méthode des orbitales moléculaires semi-empirique pour tous les électrons de valence. Sur cette base, ainsi que sur une analyse vibrationnelle du spectre expérimental, on procède à l'attribution de plusieurs transitions électroniques. La bande d'absorption de plus basse énergie (2107 Å, = 150) est attribuée à une transition n ^*. Les bandes d'absorption à 2030Å ( = 1600), 1275Å ( = 2100) et 1570Å ( = 1920) sont considérées comme des bandes 0 - 0 associées à des transitions ^*, ^* et ^* respectivement.

     

Bestimmung des komplexen dielektrischen Faktors bei niedrigen Frequenzen und der logarithmischen Ableitung von dessen Realteil unter Zuhilfenahme von Messungen der zeitabhängigen Leitfähigkeit

Zusammenfassung Es wurden Näherungen aufgestellt, die dazu ienen, *() und die besonders für dielektrische Spektraluntersuchungen interessante negative logarithmische Ableitung von () mit Hilfe der zeitabhängigen Leitfähigkeiti(t) auch bei niedrigen, der direkten Messung schlecht zugänglichen Frequenzen bestimmen zu können. Diese Näherungen sind numerisch sehr einfach zu handhaben und ihre Genauigkeit ist durch Angabe der maximal möglichen Abweichungen sicher festgelegt. Es wurde gezeigt daß die Fehlergrenzen, die man für die Hamon-Näherung finden kann, groß sind, so daß diese als viel zu unsicher angesehen werden muß.Nach den angegebenen Beziehungen lassen sich () undd/dlog allein aus der zeitabhängigen Leitfähigkeit berechnen, wenn diese bis zu hinreichend kurzen Zeiten verglichen mit dem Kehrwert der Frequenz bekannt ist. Ist dies nicht der Fall, können bei höheren Frequenzen direkt gemessene -Werte zur Berechnung mit herangezogen werden. Es wurde gezeigt, daß im Gegensatz dazu nicht mit Sicherheit ausi(t) allein bestimmt werden kann, sondern nur die Änderung von über ein vom Zeitbereich der Leitfähigkeitsmessung abhängiges Frequenzintervall. Ist in einem kleinen Frequenzbereich bekannt, dann kann es mit Hilfe voni(t) auch bei niedrigen Frequenzen ausgerechnet werden. Die dazu nötigen Beziehungen wurden mitgeteilt.

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Summary Formulae are derived for the approximative calculation of the dielectric permittivity ^*() and the logarithmic derivative of the storage component () with the aid of measurements of the transient currenti(t). These equations are numerically simple and of high accuracy. The error bounds for these equations can be given. It has been shown, that the error bounds for the well known Hamon formula are unreasonably high, indicating a great uncertainty of this relation.Some of the formulae given allow to calculate () andd/dlog from values of the transient current only, provided these are available up to values of time which are short enough compared with 1/. If this is not the case other formulae can be used for which direct measurements of at higher frequencies are necessary. Furthermore it has been shown that the knowledge of the transient current is not sufficient for calculations of . Formulae are given to obtain at lower frequencies with the aid of transient current and some values of at higher frequencies.

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Mit 1 Abbildung und 5 Tabellen     

The general form of pseudopotential operators

The general form of hermitean linear pseudopotential operators, which are independent of the virtual energies, is derived. A special case of this pseudopotential is the usually used one, ¦c>(– _c)<c¦. It is shown that any pseudopotential is of essentially non-local character. The significance of -dependency and non-hermiticity of pseudopotentials is discussed. The advantages of semiempirical model hamiltonians in comparison with exact pseudopotential hamiltonians are stressed.

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Zusammenfassung Die allgemeine Form hermitescher linearer Pseudopotentialoperatoren, die die virtuellen Orbitalenergien nicht enthalten, wird angegeben. Eine spezielle Form hiervon ist das üblicherweise verwendete Potential ¦c>(– _c). Es wird gezeigt, da\ jegliches Pseudopotential wesentlich nichtlokalen Charakter hat. Die Bedeutung von s-AbhÄngigkeit und Nicht-HermitezitÄt von Pseudopotentialen wird diskutiert. Der Vorzug von Modell-Hamiltonoperatoren gegenüber exakten Pseudo-Operatoren wird betont.

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Résumé Expression générale des opérateurs de pseudo-potentiel linéaires hermitiques, indépendants des énergies des orbitales virtuelles. Le pseudo-potentiel ordinairement utilisé ¦c>(– _c) en est un cas particulier. On montre que tout pseudo-potentiel a essentiellement un caractère non local. Discussion de la signification de la dépendance à et de la non-hermiticité des pseudo-potentiels. On souligne les avantages des hamiltoniens modèles semi-empiriques par rapport aux hamiltoniens de pseudo-potentiel exact.

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The pseudo-orbitals so defined are not normalized to unity.     

Thermal and some other properties of the complexes crystallizing from the system Ni(II)-en-[Ni(CN)4]2−-H2O

Seven complex compounds exhibiting the compositions Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) and-Ni(en)₂Ni(CN)₄ (VII) were prepared from the system Ni-en-[Ni(CN)₄]^2–-H₂O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.

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Zusammenfassung Aus einem System Ni-en-[Ni(CN)₄]^2–-H₂O wurden sieben Komplexe der Formeln Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) und-Ni(en)₂Ni(CN)₄ (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

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Ni- -[No(N)]² -₂ Ni(en)₃Ni(CN)₄ · ₂ (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄-2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2,5H₂O (VI) -Ni(en)₂Ni(CN)₄ (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .

     

Analysis of correlation effects in HeI,LiI and BeI iso-electronic sequences by Z-expansion methods

Correlation effects for the energy and the expectation values of the electron-nuclear attraction and the inter-electronic repulsion in atomic states are discussed in terms of Z expansions for these quantities. Numerical examples are given for the HeI, LiI and BeI iso-electronic sequences.It is shown that a series expansion of the type V _en =2₀Z² + ₁Z (a.u.) gives very accurate results for the expectation value of the electron-nuclear attraction.

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Zusammenfassung Der Korrelationsanteil an der Energie und an den Erwartungswerten der Elektron-Kernanziehung sowie der Elektronenabstoßung für atomare Zustände wird mit Hilfe der Z-Entwicklung dieser Größen diskutiert. Für die isoelektronischen Reihen HeI LiI und BeI werden numerische Beispiele angegeben. Es wird gezeigt, daß eine Reihenentwicklung vom Typ V _en +2Z² + ₁Z(a.E.) sehr genaue Ergebnisse für den Erwartungswert der Elektron-Kernanziehung liefert.

     

Thermal decomposition of hydrazinium monoperchlorate in the molten state

The thermal decomposition of hydrazinium monoperchlorate (HP-1) in the molten state has been investigated using differential thermal analysis, thermogravimetric analysis, a constant volume manometric technique and mass-spectrometry. The stoichiometry of the reaction can be represented by the equation: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + + 23.5 H₂OThe data seem to indicate that the mechanism, which involves an associated complex, remains unchanged from 140 to 190°. Consequently, impurities capable of forming associated complexes with the hydrazinium or the perchlorate ion desensitize the thermal decomposition of HP-1, the extent of desensitization being determined by the size, the charge and the concentration of the impurity.

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Zusammenfassung Die thermische Zersetzung von Hydrazin-monoperchlorat (HP-1) im geschmolzenen Zustand wurde unter Einsatz der Differentialthermoanalyse, der thermogravimetrischen Analyse, der manometrischen Methode mit konstrantem Volumen und der Maßenspektrometrie untersucht. Die Stöchiometrie der Reaktion kann durch folgender Gleichung dargestellt werden: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 20₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂ODie Angaben zeigen, dass der Mechanismus, in welchen ein assoziierter Komplex mit inbegriffen ist, im Temperaturenbereich von 140° bis 190° C unverändert bleibt. Folglich setzen Verunreinigungen, die mit dem Hydrazinoder dem Perchlorat-Ion assozüerte Komplexe zu bilden imstande sind, die Empfindlichkeit der thermischen Zersetzung von HP-1 herab, wobei das Ausmaß der Herabsetzung von der Grösse, der Ladung und der Konzentration der Verunreinigung abhängt.

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Résumé La décomposition thermique en milieu fondu du monoperchlorate d'hydrazinium (HP-1) a été étudiée par analyse thermique différentielle, thermogravimétrie, manométrie à volume constant et spectromètrie de masse. La réaction peut être représentée par l'équation suivante: 20 N₂H₅C1O₄ 13 NH₄C1O₄ + 3.5 Cl₂ + 2 O₂ + 13 N₂ + 0.5 N₂O + 0.5 H₂ + 23.5 H₂OLes données semblent indiquer que le mécanisme mettant en jeu un complexe associé reste inaltéré dans l'intervalle de températures allant de 140 à 190°. Par conséquent, les impuretés qui pourraient former des complexes associés avec les ions hydrazinium ou perchlorate désensibilisent la décomposition thermique de HP-1, le taux de désensibilisation étant déterminé par la taille, la charge et la concentration de l'impureté.

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(-1), , , - -. : 20 N₂H₅ClO₄ 13 NH₄ClO₄ + 3.5 l₂ + 2 ₂ + 13 N₂ + 0.5 N₂O + 0.5 ₂ + 23.5 ₂ , , - , 140° 190°. , , - , -1, , .

     

Molecular dynamics and the structure of macrocycles —Solvent acetonitrile interactions

Microwave complex permittivities,* = -J, are reported in the 1–90 GHz frequency range for the macrocycles 18-crown-6 (18C6) and 15C5 added to acetonitrile in stoichiometric proportions, in the solvent CCl₄ at 25°C. Digitized infrared spectra of the CN stretch ₂ vibration of acetonitrile for the same systems are reported in the 2300–2200 cm^–1 spectral region. The macrocycle 12C4 added to CH₃CN has also been investigated in the infrared. Both the dielectric relaxation and infrared results are interpreted in terms of macrocycle-acetonitrile interactions, probably involving a methyl-hydrogen to ethereal-oxygen interaction. These interactions with CH₃CN diminish in strength according to the sequence: 18C6 > 15C5 > 12C4.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

Eigenvalues of the real generalized eigenvalue equation perturbed by a low-rank perturbation

The low-rank perturbation (LRP) method solves the perturbed eigenvalue equation (B +V) _k = _k (C +P) _k , where the eigenvalues and the eigenstates of the related unperturbed eigenvalue equationB _i = _i C _i are known. The method is designed for arbitraryn-by-n matricesB, V, C, andP, with the only restriction that the eigenstates _i of the unperturbed equation should form a complete set. We consider here a real LRP problem where all matrices are Hermitian, and where in addition matricesC and (C +P) are positive definite. These conditions guarantee reality of the eigenvalues _k and _i . In the original formulation of the LRP method, each eigenvalue _k is obtained iteratively, starting from some approximate eigenvalue _k . If this approximate eigenvalue is not well chosen, the iteration may sometimes diverge. It is shown that in the case of a real LRP problem, this danger can be completely eliminated. If the rank of the generalized perturbation {V, P} is small with respect ton, then one can easily bracket and hence locate to any desirable accuracy the eigenvalues _k (k = 1, ...,n) of the perturbed equation. The calculation of alln eigenvalues requiresO(² n ²) operations. In addition, if the perturbation (V, P) is local with the localizabilityl p, then onlyO(² n) operations are required for a derivation of a single eigenvalue.     

Untersuchungen über die diamagnetische Suszeptibilität einiger Organo (imino-oxy)silane

Diamagnetic susceptibilities of trimethyl(imino-oxy)silanes,Me ₃SiON CMeR, and dimethyldi(imino-oxy)silanes,Me ₂Si(ON CMeR)₂, containing Si–O bonds are reported. _M of these silicon compounds has been calculated theoretically from the method ofBaudet et al. and a good agreement has been obtained between the observed _M values and the corresponding calculated values. _Si in these compounds has been calculated graphically and the lower values have been explained on the basis of back-bonding to the silicon atom from the oxygen lone pair.     

Effect of dipole position on relaxation parameters

Dielectric absorption studies have been made on numerous monobromoalkanes and two,-dibromoalkanes dispersed in polystyrene and polypropylene matrices in the frequency range 10–10⁵ Hz between 80-285 K. All compounds exhibited two clear cut dispersion regions in polystyrene except 3-bromopentane, 4-bromoheptane and 4-bromooctane. Nevertheless, when these three solute molecules are dispersed in polypropylene, they then show two dispersion regions. The low temperature process (LT) has been attributed to -CHzBr group rotation about the C-C bonds and the high temperature (HT) process to molecular rotation. In the case of,-dibromoalkanes, both -CH₂Br groups contribute to the low temperature absorption. For a bromoalkane of a given chain length the relaxation time alters with variation of the main dipole position from the terminal carbon atom to the middle of the chain for the low temperature absorption; this is related to the change in the size of the reorientating unit containing the -CHzBr group. The effect of the same variation of the dipole position on the high temperature absorption is that the relaxation time decreases which is attributed to the decrease in volume swept out on molecular rotation. The ratio,_maxLT/_(max)HT, increases with the variation of the dipole from the terminal to the middle of the chain.Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena.     

Synthesis of dimethyl sulfide in the presence of zeolites

In the presence of zeolites, dimethyl sulfide is produced either through CH₃OH interaction with H₂S or via CH₃SH decomposition. In accordance with their activities, in both reactions, zeolites arrange in the same sequence: HZSMHNaY>NaXNaY. Realization of the reaction CH₃OH+H₂S is more difficult compared to methanethiol decomposition.

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CH₃OH H₂S CH₃SH. : HZSMHNaY>NaXNaY. CH₃OH+H₂S , .

     

Effect of quantization of molecular rotations on the rate of capture in the ion-linear dipole system

The version of transition state theory that accounts for quantization of the rotational energy of a dipole gives ion-dipole capture rate constants in good agreement with the statistical adiabatic channel model and, in the region , gives results more accurate than those obtained by numerical trajectory calculations.

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, , - . , .

     

Studies of the energy spectrum of α, ω- substituted polymethine chains. II. Polymethine chains with odd number of methine groups

The analysis of the experimental data for the energy of the longest wavelength optical transitions _n,opt of substituted polymethines X (CH)_2n+1 X shows that in the asymptotic case (n) _,opt does not tend to zero, as it follows from the empirically established correlations, but has a finite, non-zero value. It is shown that the energy gap of odd polymethines is the same as that of the even polymethines - the polyenes (E 2 eV). The substituents (X N, O, B) are responsible for the appearance of levels in the gap. These, depending on the substituent character, are vacant (X B) or occupied (X N, O). The transition from or to such a level determines the longest wavelength optical transition energy of polymethines.