Unicyclic Graphs with Minimal Energy

If G is a graph and ₁,₂,..., _n are its eigenvalues, then the energy of G is defined as E(G)=|₁|+|₂|++| _n |. Let S _n ³ be the graph obtained from the star graph with n vertices by adding an edge. In this paper we prove that S _n ³ is the unique minimal energy graph among all unicyclic graphs with n vertices (n6).     

Pressure and temperature effects on the excess deuteron and proton conductance

The limiting molar conductances ° of deuterium chloride DCl in D₂O were determined as a function of pressure and temperature in order to examine the proton-jump mechanism in detail. The excess deuteron conductances °_E(D ⁺), as estimated by the equation [°_E(D ⁺) = °(DCl/D ₂ O) – °(KCl/D ₂ O)], increases with an increase in the pressure and temperature as well as the excess proton conductance [°_E(H ⁺) = °(HCl/H ₂ O) – °(KCl/H ₂ O)]. The isotope effect on the excess conductances, however, depends on the pressure and temperature contrary to the model proposed by Conway et al.: °_E(H ⁺)/°_E(D ⁺) decreases with increasing pressure and temperature. The magnitude of the decrease with pressure becomes more prominent at lower temperature. These results are discussed in terms of the pre-rotation of adjacent water molecules, the bending of hydrogen bonds with pressure, and the difference in strength of hydrogen bonds between D₂O and H₂O.     

A turbidity study of particle interaction in latex suspensions

A turbidimetric analysis of particle interaction in latex suspensions is given. The turbidity measured at different wavelengths can be rendered by the product of an integrated form factorQ(²) and a suitably defined integrated structure factorZ(²,c). This factorization rests on the expansion of the form factor of the particlesP(q) and the structure factorS(q) [q=(4/)sin(/2); : scattering angle] of the system in even powers ofq. The accuracy of this approximation has been shown by calculating the turbidity for a system of hard spheres in terms of the Percus-Yevick structure factor by numerical integration. Also, the effect of polydispersity has been taken into account within the frame of Percus-Yevick-Vrij theory for non-uniform hard spheres. It is shown that the influence of small polydispersity (standard deviation below 8%) is within experimental uncertainty. The method is applied to precise UV-spectra (400800 nm) obtained from a polystyrene latex with a diameter of 77.4 nm. The integrated structure factorZ(²,c) obtained experimentally can be interpreted in terms of an effective diameter of interaction giving a measure for the strength of electrostatic interaction.     

Circulardichroismus. XXX

Zusammenfassung Es wird eine einfache Anordnung beschrieben, die es gestattet, auf einem Zweitschreiber zum Roussel-Jouan-Dichrographen wahlweise direkt oder / aufzuzeichnen. Integration der letzteren Kurve mit einem Planimeter gibt (unter Berücksichtigung der entsprechenden Faktoren) dann die Rotationsstärke der betrachteten CD-Bande, auch wenn diese starke Peinstruktur zeigt.

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Circular dichroism XXX. On the direct determination of the rotatory strength by the roussel-jouan dichrograph

A simple device is described which can be used with the Roussel-Jouan Dichrograph to give direct readings of s and /, resp. Integration of the latter curve with a planimeter yields the rotatory strength of any partial CD-band.

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Der Deutschen Forschungsgemeinschaft danken wir sehr für die großzügige Unterstützung unserer Arbeiten.

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XXIX. Mitteilung: Snatzke, G., u. K. Schaffner [10].

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Herrn Prof. Dr. E. Asmus zum 60. Geburtstag gewidmet.     

Selective colorimetric determination of p-haloaniline in a mixture witho-haloaniline by the reaction with chloranil

Summary p-Haloanilines react with chloranil to develope an intense color (_max: 545 nm), whileo-haloanilines do not. This difference in reaction has been applied to the selective determination ofp-haloanilines in a mixture witho-haloaniline.

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Zusammenfassung p-Halogenaniline geben mit Chloranil eine intensive Farbreaktion (_max= =545 nm), während die entsprechenden o-Verbindungen dies nicht tun. Auf dieser Grundlage wurde eine selektive Bestimmungsmethode für p-halogenierte Aniline in Gemischen mit o-halogenierten Anilinen ausgearbeitet.

     

Elastizitätsmodul und Dichte von kaltverstrecktem und druckbehandeltem Polyäthylen

Zusammenfassung Proben aus Polyäthylen hoher Dichte wurden bei Raumtemperatur mit verschiedenen Geschwindigkeitenv _ver auf einer Zugprüfmaschine verstreckt. Beiv _ver 10 mm/min beobachtet man eine fast isotherm verlaufende inhomogene Deformation, die zu Verstreckungsgraden=8–13 und mittleren Dichten = 0.80 g/cm³ in den verstreckten Probenbereichen führt. Die bei höherenv _ver bis zu 50 mm/min eintretende adiabatische Erwähnung ergibt höhere Verstreckungsgrade=13–18 und geringere Dichten = 0.64 g/cm³. Es existiert kein natürlicher Verstreckungsgrad. Der Dichteabfall mit zunehmendem kann durch eine Gerade repräsentiert werden; der ElastizitätsmodulE ergibt eine mit zunehmende Kurve.Nach einer Druckbehandlung der Proben mit 5600 bar bei Raumtemperatur erreichte ihre Dichte fast wieder den Anfangswert vor der Verstreckung, wobei keine Abhängigkeit von oder anderen Parametern zeigte. Der ModulE hatte zugenommen, aber nicht proportional zur Dichte. Der Vergleich von undE verstreckter Proben vor und nach der Druckbehandlung weist auf den Netzwerkcharakter von kaltverstrecktem Polyäthylen hin.Herrn Prof. Dr. K. Ueberreiter zum 70. Geburtstag gewidmet.     

Fluordiazadiphosphetidine, 18. Mitt. Neue zwitterionische Fluordiazadiphosphetidinderivate

The reaction of (CH₃NPF₃)₂ with substituted hydrazines yields a new type of a P/N/P/N ring system by addition of one molecule hydrogenfluorid to the substituted molecule. These betain-like compounds are the first examples of a P/N/P/N ring system with one P-atom in ⁵- and the other in ⁶-conformation.

     

Reactions of phenylenedioxytrihalophosphoranes with arylacetylenes: VII. Reaction of 2,2,2-trichloro-4-fluoro-1,3,2λ<Superscript>5</Superscript>-benzodioxaphosphole with phenylacetylene

2,2,2-Trichloro-4-fluoro-1,3,2⁵-benzodioxaphosphole reacts with phenylacetylene to give 2,7-dichloro-5-fluoro-4-phenyl-2H-1,2⁵-benzoxaphosphinine 2-oxide. Hydrolysis of the latter leads to opening of the oxaphosphinine ring with formation of (E)-2-(4-chloro-2-fluoro-6-hydroxyphenyl)-2-phenylethenylphosphonic acid.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 12, 2004, pp. 1846–1851.Original Russian Text Copyright © 2004 by Mironov, Shtyrlina, Varaksina, Efremov, Konovalov.     

Peculiar Features of Reaction of 2-tert-Butoxy-5,6-benzo-1,3,2-dioxaphosphinin-4-one with Chloral. Steric Structure of 2-Chloro-3-trichloromethyl-6,7-benzo-1,4,2λ5-dioxaphopshepin-5-one 2-Oxide

The reaction of 2-tert-butoxy-5,6-benzo-1,3,2-dioxaphosphinin-4-one with chloral involves expansion of the six-membered heteroring to form 2-hydroxy-3-trichloromethyl-6,7-benzo-1,4,2⁵-dioxaphosphepin-5-one 2-oxide as a single diastereomer. The product was chlorinated with thionyl chloride to obtain (RS,SR)-2-chloro-3-trichloromethyl-6,7-benzo-1,4,2⁵-dioxaphosphepin-5-one 2-oxide.     

Structural Anisotropy of Fractal Aggregates and Its Exhibition in Electrooptical Effects

The first experimental examination of orientational turbidimetric effect [differential orientational spectrum of optical density D() in suspensions of fractal clusters was presented. Experiments were performed for aqueous suspensions of powdered Aerosil OX-50 aggregates ordered by the alternating electric field oriented along or across the unpolarized light beam. Experimental differential spectra D() are essentially different from the known spectra for bacterial and yeast suspensions. In particular, the points of zero effect lie in the red (but not in the blue) region of spectrum, and the |D()| dependence is a decreasing function in the range 300–800 nm. To explain these results, a theory was developed based on the three-dimensional lattice model of cluster-cluster aggregation and the optical model of interacting dipoles. This theory confirms main conclusions obtained previously in the Rayleigh–Debye–Hans approximation (Khlebtsov, N.G. and Mel'nikov, A.G., Kolloidn. Zh., 1998, vol. 60, no. 6, p. 843) and agrees with experimental D() spectra. It was shown experimentally and theoretically that the structural anisotropy of aggregates exhibited scale invariance, and the differential spectra for the aggregates with various numbers of particles are described by a single universal curve D(kR _g), where k= 2/ and R _gis the mean radius of gyration of aggregates.     

The phenomenon of conglomerate crystallization. XX. Spontaneous resolution in coordination compounds. XVIII.

The title compound, [cis-Co(en)₂(NO₂)₂](NO₂) (1), crystallizes in the polar, nonenantiomorphic, monoclinic space group, Cc, with lattice constants:a=9.198(2) Å,b=12.444(2),c=9.963(3), and=96.76(2)°;V=1132.39 ų andd(calc;Z=4) =1.860 g cm^–3. Thus, with NO_2– as the counteranion, [cis-Co(en)₂(NO₂)₂] crystallizes in a heterochiral lattice containing racemic pairs of cations. A total of 2699 data were collected over the range of 4°270°; of these, 1859 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=15.465 cm^–1) and the relative transmission coefficients ranged from 0.9934 to 0.7112. Refinement was carried out for both lattice polarities and the finalR(F) andR _w (F) residuals were, respectively, 0.0242 and 0.0202 for (–––) and 0.0264 and 0.0243 for (+++). Thus, the former was selected as correct for our specimen.Unlike all previous X-ray diffraction studies of the structural properties of the cation [cis-Co(en)₂(NO₂)₂]⁺, which are found to have a pair of oppositely configured en rings [i.e., () or ()], we find that in1 the cations are in the lowest energy conformation and configuration; i.e., () or (). We attribute this change in configuration to the formation of strong interionic hydrogen bonds between nitrite anion oxygens and the axial—NH₂ hydrogens, which markedly weaken the intermolecular and intramolecular hydrogen bonds between ligand—NO₂ oxygens and the hydrogens of those same amine moieties. Thus, the nitrite anions behave exactly as nitrate anions, except that the hydrogen bonds found here are stronger than those formed by the latter. This is as expected since the negative charge is delocalized over two, instead of three, oxygens.     

Investigations of hard elastic polypropylene with respect to the coil-strand-transition model

Hard elastic polypropylene was investigated by x-ray scattering using synchrotron radiation and by performing stress strain measurements in different liquids. It was found that the long period increases with elongation up to 1.3–1.4. Beyond this extension a change in the deformation behavior takes place. In the range from 1.1 to 1.3–1.4 the deformation measurements in the different liquids are in good agreement with the coil-strand-transition model. The proposed linear relationship between the deformation work and the elongation could be confirmed. The same holds for the surface energy. Moreover, the calculated ratio between the surface energy and the deformation work agrees with the measurements.     

Kinetics of Detonation Initiation in the Supersonic Flow of the H2 + O2 (Air) Mixture in O2 Molecule Excitation by Resonance Laser Radiation

The possibility of initiating detonation in the supersonic flow of the H₂ + O₂ (air) mixture behind the front of the inclined shock wave by O₂ molecule excitation to the O₂(a ¹_g) and O₂(b ¹·⁺ _g) states by laser radiation with a wavelength _I = 1.268 m and 762 nm is considered. Resonance laser radiation intensifies chain combustion due to the formation of new pathways for generating active atoms O^· and H^· and radicals OH and has a substantially nonthermal character. Even at low (3 kJ/cm²) energies of radiation with _I = 762 nm applied to the gas, detonation combustion can occur even at a distance of 1 m from the front at the gas temperature as high as 600 K.     

Organic Phosphorus-Suflur Compounds Derived from 1,3,2λ5,4λ5-Dithiaphosphetane 2,4-Disulfides. Synthesis and Properties

The results of author's research into the thiophosphorylating ability of 1,3,2⁵,4⁵-dithiadiphosphetane 2,4-disulfides in reactions with Group II, IV, V, and VI p-element derivatives containing E-X bonds (X = O, S, N) are summarized. New syntheses of organic phosphorus-sulfur compounds with P(S)SE (E = B, Al, C, Si, Ge, Sn, Ph, P, As, Sb, Bi, S) structural fragments are developed. Structural peculiarities and spectral and chemical properties of a series of representatives of these classes of organophosphorus compounds are discussed.     

Vergleich der Doppelbrechung bei optischen und Mikrowellenfrequenzen an orientierten Hochpolymeren

Zusammenfassung Es wurden die optische (r) und die dielektrische () Anisotropie an mechanisch orientierten, amorphen Hochpolymeren bei 22 °C gemessen und miteinander verglichen. Bei Polyvinylchlorid (PVC) und Polymethylmethacrylat (PMMA) zeigte sich beim Übergang von optischen (=589 nm) zu Mikrowellenfrequenzen (=3,2 cm) eine Vorzeichenumkehr und eine absolute Vergrößerung der Doppelbrechung. Daraus ergeben sich einige Schlußfolgerungen auf innermolekulare Dipolbeweglichkeiten bei Mikrowellenfrequenzen, die auf kleine Seitengruppenbeweglichkeit bei PMMA und eine schwache Segmentbeweglichkeit bei PVC hinweisen. Bei Polystyrol wurden optisch wie auch dielektrisch die gleichen Anisotropien gefunden, falls beide über die Beziehung =r² miteinander verglichen werden.Herrn Prof. Dr.W. Holzmüller sind wir für die Anregungen zu diesen Untersuchungen sowie die wertvollen Diskussionen sehr zu Dank verpflichtet.Die volkseigenen Betriebe, Celluloidwerke Eilenburg, Chemische Werke Buna, Stickstoffwerk Piesteritz unterstutzten diese Arbeit durch die freundliche Überlassung der Probenmaterialien.HerrnJ. Schultz, wissenschaftlicher Mitarbeiter im VEB Carl Zeiss Jena, danken wir für die optischen Doppelbrechungsmessungen.     

Isomerization of (Het)arylbenzoins in Basic Media

The isomerization of the hetaryl analogs of unsymmetrical benzoins on heating in basic media is a convenient preparative method for the production of -hydroxyacyl derivatives of -excessive heterocycles. The motivating force here for the isomerization is the formation of a thermodynamically more stable product. It was established that isomerization is promoted by increase in the difference between the electron-donating characteristics of the (het)aryl residues     

Ab initio investigation of the electron structure in bis-Cu+ acetylene and vinylidene complexes

[Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺ and [Cu(-C₂H₂) (-CCH₂]⁺ complexes have been studied by the ab initio double-zeta basis set method. It has been established that all calculated compounds are stable to decomposition into two C₂H₂ molecules and Cu⁺ cation and into one C₂H₂ molecules and the respective monocomplex. Calculation results suggest the possibility of intramolecular acetylene-vinylidene rearrangement in the coordination sphere of Cu⁺.

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ab initio : [Cu(-C₂H₂)₂]⁺, [Cu(-CCH₂)₂]⁺, [Cu(-C₂H₂) (-CCH₂)]⁺. C₂H₂ Cu⁺ C₂H₂ . - Cu⁺.

     

Activity in CO oxidation of manganese dioxide for batteries

The low temperature oxidation of CO over MnO₂ containing samples for batteries has been investigated. It is found that the samples contain compositional and hydrate water and Mn⁴⁺, Mn³⁺, Mn²⁺ ions. The high efficiency is due to Mn⁴⁺ content.

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CO MnO₂, . , Mn⁴⁺, Mn³⁺, Mn²⁺. Mn⁴⁺.