Structure of gossypol arylimines

A number of new Schiff's bases of gossypol with aromatic amines and sulfanilamide compounds has been obtained. It has been shown by UV and PMR spectroscopy and x-ray structural analysis that in some solvents they exist predominantly in the quinoid form. For dianilinegossypol (in the solid state) the quinoid structure has been demonstrated and two polymorphic modifications have been revealed by x-ray structural analysis.A. S. Sadykov Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 650–654, September–October, 1988.     

Synthesis and Interferon-Inducing Activity of Azo-Derivatives of Gossypol and Its Imines

New azo-derivatives of gossypol and its imines were described. Their physicochemical properties and data on their interferon-inducing activity were presented.     

Thermal analysis study of the influence of rapid solidification on the precipitation kinetics of theδ′ (Al3Li) Metastable phase in an Al-Mn-Li Alloy

The precipitation kinetics of the (Al₃Li) phase in two rapidly solidified and one conventionally cast samples of an Al-2.3Li-6.5Mn (in wt%) alloy are compared. Following high cooling rates, manganese is retained in solid solution in the aluminium matrix (Al) up to 6.0 wt%, far beyond the thermodynamic equilibrium value (0.36 wt% at 500°). Extended solid solution of manganese in aluminium induces strain gradients, similar to those produed by dislocations. The effect of such gradients, the size of which is proportional to the solute atomic fraction, is to enhance lithium precipitation, by lowering the activation energy, as observed, and also by affecting the rate parameter. Kinetic thermal analysis has been performed in a series of nonisothermal DTA experiments, operated in the heat flux DSC mode. The precipitation of the (Al₃Li) phase is evidenced by an exothermic peak whose characteristics were analyzed. The rate of transformation (precipitation) is assumed to obey the Johnson-Mehl-Avrami equation. The activation energy for the precipitation process, as well as the kinetic rate parameter have been evaluated for the rapidly solidified and the conventionally cast specimens. The activation energy for precipitation is lowered, from 105 kJ·mol^–1 for the conventionally cast material, down to 77 kJ·mol^–1 for a sample that exhibits manganese solid solubility extension of 6.00 wt%. The rate parameter for the precipitation reaction is reduced from about 1.40 for the slowly cast sample to 1.20 the rapidly solidified sample, as a result of additional stress-assisted precipitation.

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Zusammenfassung Es wird die Präzipitationskinetik der (Al₃Li) Phase in zwei schnell erstarrten und einer gewöhnlich gegossenen Probe einer Al-2.3Li-6.5Mn (in Gew.%) Legierung miteinander verglichen. Bei hohen Abkühlgeschwindigkeiten wird Mangan in der Aluminiummatrix (Al) bis zu 6.0 Gew.% als feste Lösung zurückbehalten, weit über den thermodynamischen Gleichgewichtswert (0.36 Gew.% bei 500°C) hinaus. Derart ausgedehnte feste Lösungen von Mangan in Aluminium erzeugen Spannungsgradienten, ähnlich wie die durch Versetzung hervorgerufen. Die Wirkung solcher Gradienten, deren Größe sich proportional zum gelösten Atombruch verhält, steigert, wie beobachtet durch Minderung der Aktivierungsenergie und auch durch Beeinflussung des Geschwindigkeitsparameters die Präzipitation von Lithium. Die kinetische Thermoanalyse wurde mittels einer Reihe von nichtisothermen DTA-Versuchen durchgeführt. Die Präzipitation der (Al₃Li) Phase wird durch einen exothermen Peak bewiesen, dessen Charakteristik analysiert wurde. Die Geschwindigkeit der Umwandlung (Präzipitation) scheint der Johnson-Mehl-Avrami-Gleichung zu unterliegen. Aktivierungsenergie des Präzipitationsvorganges als auch der Geschwindigkeitsparameter wurden sowohl für schnell verfestigte als auch für gewöhnlich gegossenen Proben ermittelt. Die Aktivierungsenergie für die Präzipitation wird von 105 kJmol^–1 für das gewöhnlich gegossene Material auf einen Wert von 77 kJmol^–1 für eine Probe mit einem gelösten Mangangehalt von 6.00 Gew.% gesenkt. Der Geschwindigkeitsparameter für die Präzipitationsreaktion wird von etwa 1.40 für die langsam gegossene Probe auf 1.20 für die schnell verfestigten Proben gesenkt.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

Transformation of batridene

Transformations of 1,1,6,6,7,7-hexahydroxy-3,3-dimethyl-5,5-diisopropyl-2,2-dinaphthylidene-8,8-dibarbituric acid (batridene) in DMSO are studied.     

Hydrophobic Self‐Assembly Affords Robust Noncovalent Polymer Isomers

In covalent polymerization, a single monomer can result in different polymer structures due to positional, geometric, or stereoisomerism. We demonstrate that strong hydrophobic interactions result in stable noncovalent polymer isomers that are based on the same covalent unit (amphiphilic perylene diimide). These isomers have different structures and electronic/photonic properties, and are stable in water, even upon prolonged heating at 100 °C. Such combination of covalent‐like stability together with structural/functional variation is unique for noncovalent polymers, substantially advancing their potential as functional materials.     

Random bearings and their stability

Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied.     

Space-filling bearings in three dimensions

We present the first space-filling bearing in three dimensions. It is shown that a packing which contains only loops of an even number of spheres can be constructed in a self-similar way and that it can act as a three-dimensional bearing in which spheres can rotate without slip and with negligible torsion friction.     

Os(VIII)-catalysed oxidation of sulfides by sodium salt of N-chlorobenzenesulfonamide

Catalytic activity of Os(VIII) in the oxidation of some twenty organic sulfides with sodium salt of N-chlorobenzenesulfonamide (CAB) has been investigated in alkaline (pH8.7) t-butanol–water (1:1 v/v) medium. Significant retarding influence of [OH⁻] on the reactivity is exhibited. The catalysed reaction is strongly accelerated in the presence of Hg(II). Imperfections are observed in the linear Hammett relationship in the case of –NO₂ substituents.