Crystal and molecular structure of two polymorphic modifications of <Emphasis Type="Italic">bis</Emphasis>(2,3-pentamethylene-3,4-dihydroquinazolinium) tetrachlorozincate

An X-ray diffraction investigation of two polymorphic modifications of the zinc chloride complex of 2,3-pentamethylene-3,4-dihydroquinazoline hydrochloride, grown under different temperature conditions, has been carried out. The geometry of the molecular complex is analyzed.     

Crystal Structure of a New Modification of <Emphasis Type="Italic">cis</Emphasis>-Bis(pivalyltrifluoroacetonato)copper(II)

Powder and single-crystal X-ray diffraction study of cis-bis(pivalyltrifluoro-acetonato)copper(II) has been performed (Bruker AXS P4 automatic diffractometer, MoK _β radiation, t = −25°C). Crystal data for C₁₆H₂₀CuF₆O₄: a= 9.980(7) Å, b = 19.236(13) Å, c = 20. 771(14) Å, space group Pbca, V = 3987(5) ų, Z = 8, d _calc = 1.512 g/cm³. The square-planar environment of the Cu atom (Cu-O_av 1.904 Å, =O-Cu-O_av 92.4°) is completed to bipyramidal by the atoms of the neighboring molecules, Cu...F 2.78 Å and Cu...C_γ 3.30 Å. The complex forms centrosymmetric pseudo dimers with Cu...Cu distances of 4.59 Å.Original Russian Text Copyright © 2004 by S. A. Gromilov, I. A. Baidina, P. A. Stabnikov, and G. V. Romanenko__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 893–898, September–October, 2004.     

Physico-chemical characterization of anhydrous <Emphasis Type="Italic">D</Emphasis>-mannitol

In this work the solid-state characterization of anhydrous D-mannitol has been performed: α and β modifications can be distinguished only by XRPD and FTIR as they show melting temperature and enthalpy that are the same within the standard deviation. The understanding of the thermal behaviour of the δ form (obtained by re-crystallization in acetone) has required XRPD experiments performed at variable temperature. This form during heating undergoes a solid phase transition to α modification. By cooling a melted sample, under a wide range of experimental conditions, a very fast crystallization occurs. Independently of the starting crystal form (β or δ form), the re-crystallization of D-mannitol from melt always leads to α form.     

Transformations of <Emphasis Type="Italic">ortho</Emphasis>-methoxyaryl(hetaryl)carboxamides into quinazolin-4-one and pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4-one derivatives

ortho-Chloroaryl(hetaryl)carboxamides containing one or two nitro groups at positions 3 and/or 5 of the ring undergo condensation accompanied by the pyrimidine ring closure on refluxing in an excess of sodium methoxide to form bicyclic products, viz., quinazolin-4-one, pyrido[2,3-d]pyrimidin-4-one, and pyrido[4,3-d]pyrimidin-4-one derivatives. The scheme of cyclization processes was proposed. The structures of the reaction products were confirmed by a number of physicochemical data, including X-ray diffraction analysis. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1851–1858, August, 2005.     

A new method for modification of <Emphasis Type="Italic">CN</Emphasis>-palladacycles

The reaction of benzylaminate CN-palladacycle with chlorine dioxide was found to produce the 3-chlorine-substituted analog through the formal insertion of chlorine into the Pd-C bond followed by repeated ortho-palladation of the modified ligand. The structure of the resulting dimeric complex was confirmed by X-ray diffraction study of its triphenylphosphine derivative. A comparison of the ¹H NMR spectra of the phosphine adducts of the starting and chlorinated complexes shows high conformational stability of the new palladacycle. Advantages of the new route to conformational stabilization of labile palladacycles are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2010–2019, September, 2005. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2010–2019, September, 2005.     

Crystal and Molecular Structure of 2,4-Dimethylthieno[3,4-<Emphasis Type="Italic">b</Emphasis>]-1,5-diazepinium Chloride

2,4-Dimethylthieno[3,4-b]-1,5-diazepinium chloride was obtained from 3,4-diaminothiophene hexachlorostannate and acetylacetone. Its molecular structure was established by X-ray crystallography.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.2, 273–277, February, 2005.     

Structural analysis of <Emphasis Type="Italic">w</Emphasis>/<Emphasis Type="Italic">o</Emphasis>/<Emphasis Type="Italic">w</Emphasis> multiple emulsions by means of DSC

Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems. Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are beneficial during manufacturing as in process controls, or to ensure product quality.     

UV/Vis Spectroscopic Properties of <Emphasis Type="Italic">N</Emphasis>-(2′-Hydroxy-4′-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-aminobenzylidene)-4-nitroaniline in Various Solvents and Solid Environments

Summary.  N-(2′-Hydroxy-4′-N,N-dimethylaminobenzylidene)-4-nitroaniline [HDBN] has been used as a model for investigating intra- and intermolecular D–A (donor–acceptor) interactions in various environments by means of UV/Vis spectroscopy. UV/Vis spectra of HDBN have been measured in various solvents, ethanolic solutions of different pH, adsorbed on silica, and in the solid state. A bathochromic shift of ν_max is observed with increasing the dipolarity/polarizability and HBD (hydrogen bond donor) capacity of the solvent, which is described by means of a multiple LSE (linear solvation energy) relationship in terms of the empirical Kamlet-Taft solvent polarity parameters. The adsorption of HDBN on Aerosil^? 300-silica particles in non-HBA (hydrogen bond acceptor) solvents is explained in the same sense. Mobile protons and sol–gel entrapping cause a hypsochromic shift due to protonation of the lone electron pair of the 4′-N,N-dimethylamino group. Hydroxide ions attack the 2′-hydroxy group which causes a bathochromic shift. A strong intramolecular hydrogen bond between the 2′-hydroxyl hydrogen and the imine nitrogen atom is present in the solid-state structure causing an unprecedented bathochromic shift. Corresponding author. E-mail: stefan.spange@chemie.tu-chemnitz.de Received July 8, 2002; accepted (revised) September 30, 2002     

Structure and photochromism of 2-(<Emphasis Type="Italic">N</Emphasis>-acyl-<Emphasis Type="Italic">N</Emphasis>-arylaminomethylene)benzo[<Emphasis Type="Italic">b</Emphasis>]thiophen-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004.     

Crystal structure of hinokiol isolated from <Emphasis Type="Italic">Isodon henryi</Emphasis>

Hinokiol was isolated for the first time from Isodon henryi and the structure was elucidated on the basis of IR and NMR spectra analysis. Its molecular configuration, conformation, and crystal structure were also characterized by X-ray structure analysis. The infrequent H-π stacking and hydrogen bonding assemble the molecules of hinokiol into a three-dimensional network structure. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 229–230, May–June, 2007.     

Crystal structure of <Emphasis Type="Italic">tris</Emphasis>(1,10-phenanthroline) iron(II) dinitrate dihydrate

The structure of tris(1,10-phenanthroline)iron(II) dinitrate dihydrate [Fe(phen)₃](NO₃)₂·2H₂O was established by X-ray diffraction analysis. The role of hydrogen bonds in crystal packing is discussed.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Synthesis,structure, and properties of sodium <Emphasis Type="Italic">cis</Emphasis>-tetraethylcyclotetrasiloxanolate and new mesomorphic <Emphasis Type="Italic">cis</Emphasis>-tetra[ethyl(trimethylsiloxy)]cyclotetrasiloxane

Hydrolytic condensation of ethyltriethoxysilane in the presence of NaOH (Si: NaOH = 1) gave crystal solvate of sodium cis-tetraethyltetrasiloxanolate {(Na⁺)₄[EtSi(O)O⁻]₄}·nL (1, L = EtOH, H₂O) in high yield. The molecular structure of compound 1 at L = EtOH, n = 8 was determined by X-ray diffraction analysis. The reaction of compound 1 with trimethylchlorosilane affords cis-tetra[ethyl(trimethylsiloxy)]cyclotetrasiloxane cis-[EtSi(O)OSiMe₃]₄, which is the first representative of the group of mesomorphic cyclotetrasiloxanes containing alkyl groups. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 74–79, January, 2007.     

New carborane-containing amino acids and their derivatives. Crystal structures of <Emphasis Type="Italic">n</Emphasis>-protected carboranylalaninates

New alanine derivatives containing both the carboranyl and trifluoromethyl groups were synthesized by the reaction of organometallic derivatives of o-carborane with methyl trifluoropyruvate imines. When using the 1R-(−)-menthoxycarbonyl protecting group at the nitrogen atom, one of diastereomers was isolated and characterized. Trifluoromethyl-carboranylalanine methyl esters containing different protecting groups at the nitrogen atom were studied by X-ray diffraction. Both complete and partial deprotection of the amino and carboxy groups was performed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 761–767, April, 2007.     

The self-organization properties of <Emphasis Type="Italic">n</Emphasis>-dodecylammonium α-glutamate/<Emphasis Type="Italic">n</Emphasis>-C<Subscript>5</Subscript>H<Subscript>11</Subscript>OH/water system

A biocompatible surfactant-n-dodecylammonium α-glutamate (GDA) with biodegradable and biocompatible properties was synthesized, and the phase behavior and the structural properties of GDA/n-pentanol/water system was studied by small-angle X-ray diffraction, electron spin resonance, and freeze-fracture transmission electron microscopy (FF-TEM). In the ternary phase diagram of GDA/n-pentanol/water system, there exist three isotropic regions—O/W, bicontinuous, and W/O structures, and two anisotropic regions—hexagonal liquid crystal (HEX), and lamellar liquid crystal (LLC) regions. UV irradiation causes the decrease in the interlayer space, d, of lamellar liquid crystal and in the radius, r, of column aggregates of hexagonal liquid crystal, but it has little effect on the structure of O/W and W/O microemulsions.     

Structure of the oxidative dimerization product of 4,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)pyrogallol

The structure of the oxidation product of 4,6-di(tert-butyl)pyrogallol, viz., 6,10a-dihydroxy-3,4a, 7,9-tetra(tert-butyl)-1,2,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxine-1,2-dione, was established by X-ray diffraction. Dimerization of intermediate 3-hydroxy-4,6-di(tert-butyl)-1,2-benzoquinone occurs by the mechanism of Diels—Alder heterocyclization. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 267–271, February, 2007.     

Crystal structure of Bis(<Emphasis Type="Italic">N</Emphasis>-benzyl)salicylideneiminatocobalt(II)

Crystal structure of Co^IIL₂ complex (where L is (N-benzyl)salicylideneiminate ion) is determined by X-ray diffraction analysis. In this mononuclear molecular complex (with C₂ symmetry), the Co atom has a distorted tetrahedral coordination to two O atoms and two N atoms of two bidentate chelate ligands L (Co-O 1.919(2) Å and Co-N 2.009(2) Å; angles OCoO(A) 113.17(7)°, NCoN(A) 125.44(7)°, and OCoN 96.22(7)°).Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 28–31.Original Russian Text Copyright © 2005 by Aleksandrov, Shirokii, Sergienko.     

Ultrasound-accelerated one-pot synthesis of <Emphasis Type="Italic">N</Emphasis>-acetyl-2-aryl-1,2-dihydro-4<Emphasis Type="Italic">H</Emphasis>-3,1-benzoxazin-4-ones

The one-pot synthesis of N-acetyl-2-aryl-1,2-dihydro-4H-3,1-benzoxazin-4-one derivatives from the condensation reaction of anthranilic acids with heteroaromatic aldehydes in the presence of excess amount of acetic anhydride has been explored. The reactions proceed smoothly under ultrasound irradiation and without catalyst at 35 − 40 °C to afford the title products in high yields.