Regioselective alkylation of the lower rim of p-tert-butylthiacalix[4]arene with N-(p-nitrophenyl)-α-bromoacetamide

The preparation of partially substituted thiacalix[4]arenes 2–6 has been accomplished by conducting the reaction of the thiacalixarene 1 with N-(p-nitrophenyl)-α-bromoacetamide in acetone or acetonitrile in the presence of M₂CO₃ (M = Na, K and Cs). The influence of the reaction conditions (temperature, time, solvent, ratio of the reagents and the nature of the alkali metal carbonate) on regio- and stereoselectivity of this reaction is described.     

Synthesis, structure, and properties of nitronyl nitroxyl tetraradical with calix[4]arene framework

A reaction of calix[4]arene tetraaldehyde with 2,3-bis(hydroxyamino)-2,3-dimethylbutane in DMF resulted in the corresponding 1,3-dihydroxyimidazolidine tetraadduct, whose oxidation gave a calix[4]arene (1,3-alternate) bearing four nitronyl nitroxyl-containing substituents at the upper rim.     

The Novel Phosphadiazacalixcrown Compounds

Abstract

A new series of calixcrown compounds (11) containing some VA group elements (N, P) was synthesized. 1.3-bis-(aminoethoxy) calix[4]arene (I) was used as starting platform for the preparation of calixcrown compounds. Reaction of (I) with bis(a-hydroxyalky1)phenylphosphines in toluene lead to phosphadiazacalixcrown compounds (11). All obtained receptors are hydrolytic stable and are not oxidized by air. A more convenient synthesis of (II) involves treatment of (I) with 2.5-diphenyl-1.3.2.5-dioxaboraphosphorinanes (III) which are stable on air unlike bis-(a-hydroxyalkyl) phenylphosphines. Structure of obtained macrocycles was established by ¹H and ³¹P NMR spectroscopy.     

Hydrates and ammonium salts of 4-nitrobenzenesulfonic acid: supramolecular organization and its relation to proton conductivity

Structural features, the crystal packing, and the proton conductivity of a series of hydrates and ammonium salts of 4-nitrobenzenesulfonic acid were studied. It was shown that infinite cation associates containing the onium moiety are responsible for a substantial increase in the proton conductivity. The nature of the disorder in a series of crystals was investigated by performing X-ray diffraction studies at different temperatures. A new type of structural synthons, viz., anion-anion dimers stabilized by the SO₃ ⁻…NO₂ interaction, was found and characterized and the role of solvent water molecules was elucidated based on high-resolution X-ray diffraction data. The water molecules serve mainly as channels for charge transfer from the cation to the anion with retention of the electroneutrality.     

Mechanically induced chemiluminescence in the dispiro(adamantane-1,2-dioxetane)—Eu(fod)3 system

Luminescence accompanying an impact mechanical treatment of solid particles of the complex of Eu(fod)₃ (fod is 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,6-dione) with dispiro(adamantane-1,2-dioxetane) (1) was discovered and studied. The luminescence has a complex structure, and its spectrum belongs to the excited Eu^III ions. The emission of light is observed only in a mechanical mixture of the Eu(fod)₃ with dioxetane1 and in their cocrystallized form, but not in the case of the components taken separately. The mechanism by which the impacts cause the luminescence is considered. It was shown that the luminescence is not triboluminescence, but is chemiluminescence induced by the decomposition of compound1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1159–1162, May, 1996.     

The role of free radicals in the reaction of dimethyldioxirane with adamantane

The products and the kinetics of the reaction of dimethyldioxirane with adamantane in CCl₄ were studied. It was found that the reaction simultaneously occurred via molecular and radical paths. The contribution of the radical process was 65% at 30.6°C. The activation parameters of the reaction of dimethyldioxirane with adamantane in the presence of an inhibitor were determined: logk = (7.33 ± 0.14)-(58.5 ± 0.8)/, = 2.3RT(kJ/mol) (10.3–69.3°C).Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 859–862.Original Russian Text Copyright © 2004 by Grabovskiy, Antipin, Kabalnova.     

Pentakis(carbamide)dioxoneptunium(V) Nitrate [NpO2{OC(NH2)2}5](NO3): Synthesis,Crystal Structure,and Some Properties

X-ray diffraction and spectroscopic data for a new Np(V) compound, namely, [NpO₂{OC(NH₂)₂}₅](NO₃) (I) are presented. Crystals are monoclinic, space group P2₁, a = 11.142(2) Å, b = 7.6379(9) Å, c = 11.143(2) Å, = 108.9(1)°, Z = 2, V = 897.1(2) ų. The neptunium atom has a typical pentagonal-bipyramidal environment with five oxygen atoms of the carbamide molecules in the equatorial plane. The nitrate ion is in the outer sphere. Carbamide is a strong molecular ligand with respect to Np(V) and hence, cation–cation bonds of the NpO₂ ⁺ ions are not realized in structure I. The wave length of the f–f transition in the electronic absorption spectra of crystalline complex I and Np(V) in a saturated carbamide solution is virtually the same and is equal to 991 nm.