Synthesis of Highly Functionalized Cyclobutene Derivatives

Summary. Protonation of the reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates with CH-acids, such as ethyl 2,4-dioxo-hexanoate and ethyl 2,4-dioxo-5-methylhexanoate, lead to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce cyclobutene derivatives in fairly high yields.Received November 8, 2002; accepted November 29, 2002 Published online July 3, 2003     

Regioselective Heteroannelation in 4-Cyanomethyl-3,5-pyridinedicarbonitriles. Synthesis of 6-Alkoxy-3-dialkylamino-1,8-diamino-2,7-naphthyridine-4-carbonitriles

Summary.  The title naphthyridines were found to be the sole products obtained after treatment of 2-amino-4-cyanomethyl-6-dialkylamino-3,5-pyridinedicarbonitriles with alkoxides. The starting pyridine derivatives were prepared by amination of the readily available 2-amino-6-chloro-4-cyanomethyl-3,5-pyridinedicarbonitrile in quantitative yields. Corresponding author. E-mail: atver@mail.univ.kiev.ua Received November 4, 2002; accepted November 22, 2002 Published online May 6, 2003     

Protoberberines from <Emphasis Type="Italic">Reissert</Emphasis>-Compounds VIII [1]. Oxazoloisoquinolines,New and Efficient Educts for the Synthesis of 8-Oxoprotoberberines

Summary.  Certain benzylated oxazoloisoquinolinones readily available from Reissert compounds provided an efficient access to 8-oxoprotoberberines in three steps. A series of these new precursors as well as several oxoprotoberberines were prepared and the scope and limitation of this procedure were investigated. Corresponding author. E-mail: ebrei@cup.uni-muenchen.dem Part of PhD thesis, LMU München, D Received October 31, 2002; accepted November 5, 2002 Published online May 6, 2003     

Ferromagnetism in Metallocene-Doped Fullerenes

 Ferromagnetism in fullerene-based systems doped with metallocenes is reviewed. These compounds form a ferromagnetic state by spin-coupling between π electrons on fullerene units, while the metallocene molecules do not contribute to the spin ordering. One of these compounds has the highest critical temperature (19 K) for this class of compound. The magnetic properties of these materials are very strongly dependent on the crystallization conditions. Corresponding author. E-mail: Dragan.Mihailovic@ijs.si Received September 4, 2002; accepted September 6, 2002     

In-House pH Reference Materials

 In-house pH reference materials (IHRMs) traceable to the corresponding NIST pH standards have been developed. Characterization of the IHRMs was based on a comparative approach implying transmission of measurement information from the corresponding standard to the IHRM by simultaneous pH measurements in solutions of both the IHRM and the standard under the same conditions. While the measurements were performed, a statistically detectable temporal drift of the measurement system took place. This did not hinder extraction of the necessary measurement information by way of the comparative approach applied. Correspondence: The National Physical Laboratory of Israel (INPL), Givat Ram, Jerusalem 91904, Israel. e-mail: ilya_kus@netvision.net.il Received August 20, 2002; accepted November 8, 2002     

A New Mechanism of Thermochromism for Silica Sol-gel Materials

Summary.  In this contribution we provide evidence for thermochromic colour changes unique to silica based materials formed at low temperature by the sol-gel process. The mechanism requires the matrix and the dopant to interact in order to produce the observed colour changes. The materials formed have potential application as temperature sensitive light filters, visual temperature indicators, self-diagnostic labels for electronic devices and infrared recording media. Corresponding author. E-mail: carole.perry@ntu.ac.uk Received June 28, 2002; accepted July 30, 2002     

Localized Orbitals vs. Pseudopotential-Plane Waves Basis Sets: Performances and Accuracy for Molecular Magnetic Systems

 Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbitals, has become the method of choice for calculating the exchange-couplings in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50–300 cm⁻¹). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm⁻¹ to −300 cm⁻¹. The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably employed to predict and rationalize the magnetic properties of molecular-based materials. Corresponding author. E-mail: Carlo.Massobrio@ipcms.u-strasbg.fr Received August 5, 2002; accepted August 9, 2002     

Solubility of Uric Acid in Lithium Chloride Solutions

Summary.  The solubility of anhydrous uric acid was measured in 0.30 mol dm⁻³ LiCl solutions as a function of hydrogen ion concentration at 25 and 37°C. No influence of the lithium ion on the solubility of uric acid was detected. The “litholytic” effect of lithium reported in literature can possibly be explained by the higher solubility of lithium hydrogenurate as compared to other alkali metal hydrogenurates. Corresponding author. E-mail: koenigsb@chem.murdoch.edu.au Received November 21, 2002; accepted December 10, 2002 Published online April 7, 2003 RID="a" ID="a" Dedicated to Professor Heinz Gamsj?ger on the occasion of his 70th birthday     

Metal-Containing Phthalocyanines Substituted with One Branched Bulky Moiety and Six Alkylthio Groups

Summary.  Unsymmetrically substituted metal-phthalocyanines composed of three hexylthio groups and one 1-chloro-3,4-dicyano-6-[2-(2-pyridylmethylamino)phenylthio]benzene moiety was prepared by cyclization of the reactants in the presence of the anhydrous metal salts Zn(CH₃COO)₂, NiCl₂, and CoCl₂. The new unsymmetric phthalocyanines are very soluble in common organic solvents. The compounds were characterised by their elemental analyses, IR, ¹H NMR, MS and UV/Vis spectra. Corresponding author. E-mail: bayir@itu.edu.tr Received November 27, 2002; accepted (revised) December 2, 2002 Published online May 2, 2003     

Pinacol Formation and Reduction of Aromatic Carbonyls with Magnesium–Methanol at Ambient Temperature

Summary. A simple and inexpensive procedure for the pinacol formation of aromatic aldehydes and reduction of aromatic ketones to the corresponding alcohols with magnesium in dry methanol at ambient temperature is reported. The pinacol formation and reduction are proposed to be proceeding by SET from magnesium.Received November 26, 2002; accepted (revised) March 7, 2003 Published online September 25, 2003     

Suppression of Formation of N,N′-Dicyclohexylurea Derivatives During DCC-Activation of Proline-Containing Dipeptides

Summary.  The syntheses of dipeptide esters containing a C-terminal L-proline moiety using carbodiimides as coupling reagents strongly depend on the choice of appropriate conditions. Thus, the use of DCC prefers the formation of the undesirable N,N′-dicyclohexylurea derivative 3 as a consequence of a CO → N-shift in the O-acyl isourea intermediate instead of the desired dipeptide ester 4. In our hands, only DIC was able to yield the desired product exclusively. E-mail: radau@pharmazie.uni-greifswald.de Received November 7, 2002; accepted December 4, 2002 Published online May 6, 2003     

Analysis of Carbohydrate Mixtures by Diffusion Difference NMR Spectroscopy

Summary.  Diffusion difference NMR spectroscopy can be used as a fast and powerful tool to separate carbohydrates in a mixture by their translational diffusion properties. This method is of general interest for analyzing natural and synthetic mixtures and for monitoring and optimizing synthetic reactions. The proposed subtraction procedure applied to two varying diffusion encoded spectra can be combined with homo- and heteronuclear as well as with one- and multi-dimensional NMR experiments. Received November 26, 2001. Accepted November 30, 2001     

Solubility Behavior in Ternary Water-Salt Systems under Sub- and Supercritical Conditions

Summary.  Two main types of binary systems with distinctive solubility behavior under sub- and supercritical conditions were used to subdivide ternary water-salt systems into three classes. Characteristic features of solubility behavior and phase equilibria in ternary water-salt systems of each class at temperatures above 200°C are discussed on the basis of available experimental data and some conclusions obtained as a result of theoretical derivation of fluid and complete phase diagrams. Corresponding author. E-mail: Valyashko@IGIC.RAS.RU Received September 25, 2002; accepted (revised) November 28, 2002 Published online April 24, 2003 RID="a" ID="a" Dedicated to Prof. Dr. H. Gamsjaeger on the occasion of his 70^th birthday anniversary     

Ground- and excited-state properties of inorganic solids from full-potential density-functional calculations

The development in theoretical condensed-matter science based on density-functional theory (DFT) has reached a level where it is possible, from “parameter-free” quantum mechanical calculations to obtain total energies, forces, vibrational frequencies, magnetic moments, mechanical and optical properties and so forth. The calculation of such properties are important in the analyses of experimental data and they can be predicted with a precision that is sufficient for comparison with experiments. It is almost impossible to do justice to all developments achieved by DFT because of its rapid growth. Hence, it has here been focused on a few advances, primarily from our laboratory. Unusual bonding behaviors in complex materials are conveniently explored using the combination of charge density, charge transfer, and electron-localization function along with crystal-orbital Hamilton-population analyses. It is indicated that the elastic properties of materials can reliably be predicted from DFT calculations if one takes into account the structural relaxations along with gradient corrections in the calculations. Experimental techniques have their limitations in studies of the structural stability and pressure-induced structural transitions in hydride materials whereas the present theoretical approach can be applied to reliably predict properties under extreme pressures. From the spin-polarized, relativistic full-potential calculations one can study novel materials such as ruthenates, quasi-one-dimensional oxides, and spin-, charge-, and orbital-ordering in magnetic perovskite-like oxides. The importance of orbital-polarization correction to the DFT to predict the magnetic anisotropy in transition-metal compounds and magnetic moments in lanthanides and actinides are emphasized. Apart from the full-potential treatment, proper magnetic ordering as well as structural distortions have to be taken into account to predict correctly the insulating behavior of transition-metal oxides. The computational variants LDA and GGA fail to predict insulating behavior of Mott insulators whereas electronic structures can be described correctly when correlation effects are taken into account through LDA+U or similar approaches to explain their electronic structures correctly. Excited-state properties such as linear optical properties, magneto-optical properties, XANES, XPS, UPS, BIS, and Raman spectra can be obtained from accurate DFT calculations.     

Spintronics and spintronics materials

The review concerns the fundamentals of spintronics (spin-transport electronics). The material covers spin-spin interactions and spin relaxation in semiconductors as well as spin and spin injection related effects in the condensed matter. Examples of promising spintronic devices are given, requirements for spintronic materials are formulated, methods of synthesis of spintronic materials are described, and the physicochemical properties of some materials are characterized. Organic spintronic materials are briefly outlined and the state-of-the art in the field of research on inhomogeneous magnetic semiconducting materials possessing high-temperature ferromagnetism is described. The emphasis is placed on the chemical bonding and electronic structure of magnetic impurities in semiconductors, consideration of the nature of ferromagnetism, and on the character of exchange interactions between localized spins in novel spintronic materials.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2255–2303, November, 2004.     

An overview of developments in poly(urethane‐isocyanurates) elastomers

The growth of the science and technology of plastics leads to the development of new materials with more desirable properties. Such kinds of materials include polyurethanes with isocyanurate structural units combining the properties of great strength and high temperature stability. Most of them are produced as rigid foams designed as insulation materials for industrial applications. However, great progress has been made with the introduction of isocyanurate rings in the non‐cellular areas, especially in elastomers. The aim of this work is to present an overview of the major developments on the field of poly(urethane‐isocyanurate) elastomers. Copyright © 2002 John Wiley & Sons, Ltd.     

Solubility of Lanthanide Chlorides ( Ln Cl3) in Alkali Metal Chlorides ( M Cl): Thermodynamics and Electrical Conductivity of the M 3 Ln Cl6 Compounds

Summary.  Several compounds may exist in LnCl₃–MCl mixtures. Those corresponding to the M ₂ LnCl₅ and MLn ₂Cl₇ stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide and alkali metal. On the other hand, M ₃ LnCl₆ that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport properties were correlated to structural features and related to the mechanism of compound formation. Corresponding author. E-mail: Marcelle.Gaune-Escard@polytech.univ-mrs.fr Received October 2, 2002; accepted November 6, 2002 Published online April 24, 2003 RID="a" ID="a" This paper is dedicated to Professor H. Gamsj?ger on the occasion of his birthday     

Synthesis and Comparative Analysis of Molecular and Supramolecular Structures of 4,8-Disubstituted 1,5-Dichloro-2,6-dioxotricyclo[5.1.0.0 3,5]octanes

Summary. A series of 4,8-disubstituted 1,5-dichloro-2,6-dioxotricyclo-[5.1.0.0^3,5]octanes, synthesized by various methods, were studied by X-ray single crystal diffraction. The conformation (syn/anti) of the molecules does not depend on the method of preparation and nature of substituents. All the compounds crystallize in centrosymmetric space groups with half of the molecules in the asymmetric part of the unit cell. The main influence which the substituents render is on the packing of molecules in crystals and on the types of intermolecular interactions and supramolecular structures.Received November 7, 2002; accepted (revised) December 16, 2002 Published online June 23, 2003     

The Prebiotic Synthesis of Acrolein

Summary.  Acrolein is a central intermediate in the prebiotic synthesis of several amino acids, pentaerythritol, as well as various postulated alternative genetic materials. Acrolein is highly reactive so that its steady-state concentration could not have been very high. The ease of synthesis of acrolein from the aqueous aldol condensation of acetaldehyde and formaldehyde was therefore of interest. It is shown here that acrolein is produced in a low, but significant, steady-state concentration from very dilute solutions of formaldehyde and acetaldehyde under neutral to basic conditions. Acrolein is produced under conditions that are too dilute for the oligomerization of formaldehyde to produce carbohydrates. The implications of these findings for prebiotic chemical evolution are discussed. Corresponding author. E-mail: hcleaves@ucsd.edu Received June 18, 2002; accepted July 9, 2002     

4-Aminobicyclo[2.2.2]octanone Derivatives with Antiprotozoal Activities

Summary.  4-Aminobicyclo[2.2.2]octanones which were prepared in one-pot-reactions from benzylidene acetone and dialkylammonium rhodanides were reduced stereoselectively to their corresponding alcohols. The activities of the bicyclic compounds against causative organisms of tropical deseases were examined. The 4-aminobicyclo[2.2.2]octan-2-ols were in general more active against Trypanosoma b. rhodesiense and Plasmodium falciparum than the corresponding keto compounds. Corresponding author. E-mail: robert.weis@uni-graz.at Received November 27, 2002; accepted December 2, 2002 Published online May 2, 2003