bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Gene Fragments in Genetic Engineering—The Renaissance of Chemistry in Molecular Biology
Authors: Davies Julian E. , Gassen Hans Günter 
Published: December 2003

AbstractChemistry and biology paved the way for a new scientific discipline, molecular genetics. The breathtaking progress in deciphering the genetic machinery of a living being within the last 20 years may be attributed mainly to the experimental skill and ingenuity of molecular biologists. Chemists lost interest in the investigation of biological problems. The advances in genetic engineering exemplify the new demands chemists are confronted with in contemporary science. Following a short introduction on the genetics of bacteria, the articles deals with the molecular basis of gene cloning, which is subdivided into in vitro recombination of nucleic acids and in vivo transformation of cells. Next, the criteria for the selection of passenger DNA, vectors, and host cells are discussed. Recombination and transformation are easy‐to‐learn experimental techniques, whereas the search for the positive clone requires detailed knowledge of microbiology and the ability to handle of a battery of modern biochemical techniques. Finally, the automated chemical synthesis of gene fragments serves to demonstrate that chemistry is starting to make its comeback into molecular biology.
NMR Studies of Yeasts Grown on Substrates at “Zero” Level Radioactivity
Authors: Basosi Ricardo , Rossi Clausio , Tiezzi Enzo , Valensin Gianni 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 57. DOI:10.1002/anie.198300570
Tellurium as Six‐Electron Donor‐Synthesis and Structure of μ3‐Te[Mn(CO)2(η5‐C5H5)]3
Authors: Herberhold Max , Reiner Dietmar , Neugebauer Dietmar 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 10. DOI:10.1002/anie.198300100
On the Description of Complex Inorganic Crystal Structures
Authors: Andersson Sten 
Published: December 2003

AbstractTo describe a structure is to describe chemistry. A description of structure should be simple yet also open up ways for an understanding of complex structures and their properties. Such interrelationships are gained on inspection and discussion of structures in models of interpenetrating partial structures and on application of symmetry operations to whole structures. Transition regions between interpenetrating partial structures can be approximated to periodic minimal surfaces. Chemical reactions, e.g. in ion‐exchange, in heterogeneous catalysis, or in molecular separations in complicated zeolites will take place on these minimal surfaces.
Oxidative Coupling of the Selenolate Functions in (C6H5)3PC(Se)P(C6H5)3: Crystal Structure of {[(C6H5)3P]2CSe}Fe2OCl·4CH2Cl2 Containing a Linear FeOFe Axis
Authors: Schmidbaur Hubert , Zybill Christian E. , Neugebauer Dietmar 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 169. DOI:10.1002/anie.198301690
Successive Electron Transfers in Molecules with Two Electrophoric Groups: Novel Singlet, Doublet, and Triplet States
Authors: Huber Walter , Unterberg Heinz , Müllen Klaus 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 288. DOI:10.1002/anie.198302880
Reactions of N‐Methylenecarboxamides with Electrophiles: 1‐Alkoxy‐2‐azaallenium Salts and N‐Acyl(methylene)ammonium Salts
Authors: Würthwein Ernst‐Ulrich , Kupfer Rainer , Kaliba Claus 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 264. DOI:10.1002/anie.198302640
Straightforward Preparation and Stabilization of 2‐trans‐4,7: 10,13‐Diepoxy[15]annulenone
Authors: Ogawa Haru , Inoue Tadashi , Imoto Taiji , Miyamoto Izumi , Kato Hidefumi , Taniguchi Yōichi 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 243. DOI:10.1002/anie.198302430
Can Radicals Participate in Pericyclic Reactions? Model Reactions for Electron‐Transfer Induced Valence Isomerization of 1‐Arylindenes
Authors: Kiesele Herbert 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 210. DOI:10.1002/anie.198302100
Tetraethoxyallene: Equivalent of the Fictive Malonic Ester Dianion—A Versatile Synthetic Building Block
Authors: Saalfrank Rolf W. , Rost Walter 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 451. DOI:10.1002/anie.198304510
Modern Pulse Methods in High‐Resolution NMR Spectroscopy
Authors: Benn Reinhard , Günther Harald 
Published: December 2003

AbstractThe introduction of Fourier transform methods has not only remarkably enhanced the sensitivity of high‐resolution NMR spectroscopy, thus allowing measurements to be made on less sensitive nuclei of the Periodic Table, but also has paved the way for the development of a large number of new experimental techniques. On the one hand, procedures already known have been improved and can now be performed more rapidly, and, on the other, completely new experimental approaches have become available. This situation resulted mainly from the introduction of programmable pulse transmitters and the separation of the experiment into preparation, evolution, and detection. In particular, the concept of two‐dimensional spectroscopy has opened up new possibilities important for the analysis of complicated spectra and is able to provide information previously not accessible. As elsewhere, optimum application of the techniques and correct interpretation of the results require sound understanding of the underlying physical principles. Since a rigorous mathematical treatment is complicated and does not necessarily improve the comprehensibility, this article attempts to give an illustrative presentation of the new pulse techniques within the framework of the Bloch vector model. After a short introduction covering the basic principles, one‐dimensional pulse techniques that can be applied using standard experimental equipment are dealt with. The main areas of application are signal assignment, sensitivity enhancement for measurements on less abundant nuclei, and selective excitation of individual resonances. Subsequently, the various techniques of two‐dimensional NMR spectroscopy are treated: these enable shift correlations for different types of nuclei to be made, the presentation of spin multiplets without overlap, and the analysis of geometrical relations as well as of chemical exchange phenomena.
syn‐Benzene Dioxide/1,4‐Dioxocin Systems via a Diels‐Alder Route
Authors: Altenbach Hans‐Josef , Voss Burkhard , Vogel Emanuel 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 571. DOI:10.1002/anie.198305710
Synthesis of an [18]Annulene Dioxide: An Oxygen‐Bridged [18]Annulene Possessing Equivalent Kekulé Structures
Authors: Ogawa Haru , Sadakari Naomi , Imoto Taiji , Miyamoto Izumi , Kato Hidefumi , Taniguchi Yōichi 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 471. DOI:10.1002/anie.198304710
Synthesis of Hetero[17]annulene Dioxides and a [16]Annulene Dioxide Using Furan Building Blocks
Authors: Ogawa Haru , Fukuda Chiyuki , Imoto Taiji , Miyamoto Izumi , Kato Hidefumi , Taniguchi Yōichi 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 480. DOI:10.1002/anie.198304800
Electron Diffraction with the Transmission Electron Microscope as a Phase‐Determining Diffractometer—From Spatial Frequency Filtering to the Three‐Dimensional Structure Analysis of Ribosomes
Authors: Hoppe Walter 
Published: December 2003

AbstractChemists recognize X‐ray crystal structure analysis and electron microscopy as powerful methods of analysis. In the last 20 years the basic ideas of X‐ray diffraction analysis have been extended to the field of electron microscopy, whereby an image‐forming apparatus is converted into an electron diffractometer, and through which an old dream of crystallographers can be realized—the measurement of the phase shift of scattered waves, a prerequisite for the direct calculation of structures. Its most important area of application, like that of the X‐ray diffractometer, is in three‐dimensional structure analysis—in all fields of science. However, beyond crystallography, aperiodic structures (comparable to crystals with a single unit cell) can also be analyzed three‐dimensionally. In this progress report, the development of the first idea (spatial frequency filtering) to the analysis of ribosomal particles is outlined. Attention will be focused primarily on quantitative methods for the measurement of scattered rays, which are also usable beyond the conventional limit of resolution, down to atomic resolution. In the course of this work in 1968, the principle of the three‐dimensional analysis of native biological crystal structures using the electron microscope, as worked with today in many laboratories, was developed. In Munich, however, further research focused on the three‐dimensional analysis of aperiodic and individual (especially biological) objects. The analysis of 50S‐subunits of the procaryotic ribosome ofE. colishowed surprisingly good reproducibility of the results (although only within the same orientation), allowing the deduction of almost ideal average model structures from a limited number of particles.
Novel Nickel‐Oligomerization Catalysts with Arsenic‐Oxygen Chelate Ligands
Authors: Keim Wilhelm , Behr Arno , Limbäcker Brigitte , Krüger Carl 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 655. DOI:10.1002/anie.198306550
1‐(1,3‐Butadienyl)triazoles from 1‐Vinyltriazoles and Electron‐Rich Alkynes‐Cleavage to “Push‐Pull” 1,3‐Butadienes
Authors: Schubert Hans , Regitz Manfred 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 726. DOI:10.1002/anie.198307260
Olefins from β‐Hydroxycarboxylic Acids—Synthesis of Isomerically Pure α‐ and β‐Asarone
Authors: Mulzer Johann , Lammer Ortrud 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 887. DOI:10.1002/anie.198308870
Ligand‐Free Metal Clusters
Authors: Ozin Geoffrey A. , Mitchell Steven A. 
Published: December 2003

AbstractRecent advances in the synthesis and spectroscopic characterization of ligand‐free metal clusters immobilized in cryogenic rare gas matrices have contributed greatly to the understanding of electronic, geometric, dynamic, and chemical bonding properties of a wide range of uni‐ and bimetallic clusters as a function of nuclearity and metal type. The knowledge accumulated on molecular metal aggregates devoid of ligands and isolated on various supports will form an important data base for gauging the reliability of quantum chemical calculations on metal clusters, as well as for comprehending certain aspects of chemisorption on, and catalysis by, supported metal clusters. It can be envisaged that information on ligand‐free metal clusters entrapped in a wide range of matrix environments in conjunction with the data for these same metal clusters in the gas phase and in molecular beams will probably contribute towards understanding metal‐support interactions and to the designed synthesis of a new breed of high‐technology heterogeneous catalysts in the not too distant future.
29Si‐E(lectron)N(uclear)DO(uble)R(esonance)
Authors: Bock Hans , Hierholzer Bernhard , Kurreck Harry , Lubitz Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1088. DOI:10.1002/anie.198310880
Secologanin, a Biogenetic Key Compound—Synthesis and Biogenesis of the Iridoid and Secoiridoid Glycosides
Authors: Tietze Lutz‐F. 
Published: December 2003

AbstractThe monoterpene glycoside secologanin is a key intermediate in the biosynthesis of most indole, cinchona, ipecacuanha, and pyrroloquinoline alkaloids, as well as of simple monoterpene alkaloids. More than a thousand alkaloids are formed from secologanin in vivo; this represents almost a quarter of this large group of natural products. It is also the parent compound of the secoiridoids. Many of the compounds derived from secologanin display a high degree of biological activity and are employed as pharmaceuticals, e.g., the dimeric indole alkaloid leurocristine (vincristine) which is used very successfully in the treatment of acute leukemia. A knowledge of the biosynthesis and biological reactions of secologanin provides a sound basis for the biosynthesis‐orientated classification of numerous natural products and the taxonomy of many plants. Secologanin and structurally related substances can be synthesized in a few steps by stereocontrolled photochemical and thermal cycloadditions. Its biomimetic reaction with amines and amino acids yields other natural products and compounds of pharmacological interest.
Tricyclo[4.1.0.01,3] hept‐4‐enes as Intermediates
Authors: Brinker Udo H. , Gomann Klaus , Zorn Ruth 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1241. DOI:10.1002/anie.198312410
Resolution, Circular Dichroism, and Absolute Configuration of 1,1′‐Biazulenes
Authors: Tajiri Akio , Fukuda Masahiko , Hatano Masahiro , Morita Tadayoshi , Takase Kahei 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1283. DOI:10.1002/anie.198312830
Reaction Control by Catalysts with Variable Specificity: Stable Palladium‐Phthalocyanine as Hydrogenation Catalyst with Three Catalytic Patterns
Authors: Eckert Heiner , Fabry Gudrun , Kiesel Yvonne , Raudaschl Gabriele , Seidel Christoph 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1291. DOI:10.1002/anie.198312910
Synthesis and Structure of (Z)‐3‐Amino‐4‐oxo‐2‐azetidinesulfonic Acids
Authors: Hoppe Dieter , Sheldrick George M. , Egert Ernst , Kaars Petra 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1333. DOI:10.1002/anie.198313330
Electron‐Rich Half‐Sandwich Complexes—Metal Bases par excellence
Authors: Werner Helmut 
Published: December 2003

AbstractElectron‐rich, half‐sandwich complexes of the type CnRnML2 or CnRnMLL′ are built up of an aromatic five‐ or six‐membered ring, a d8‐metal, and either a pair of two‐electron donors or an equivalent chelating ligand. Such complexes behave like Lewis bases and react with a wide variety of electrophiles, El or ElX, to form products with a new metal‐element bond. According to their reactivity they are comparable to the Vaska‐type compounds. Certain of the products obtained after addition of the electrophile undergo interesting subsequent reactions in which, for example, metal complexes containing molecules that are unstable in the free state, such as CS, CSe, CH2S, CH2Se, CH2Te, CH3CHS, CH3CHSe, CH2CS, CH2CSe, and CH2CTe are formed. Moreover, cycloadditions as well as reactions with coordinatively unsaturated transition‐metal compounds which result in formation of heterometal binuclear complexes demonstrate that the metal bases CnRnML2 and CnRnMLL′ are valuable synthetic building blocks. Furthermore, very recent investigations have indicated links between metal basicity and the problem of CH activation.
Synthesis and Structure of a Diarsenechromium Complex with an Unsupported Arsenic‐Arsenic Double Bond
Authors: Cowley Alan H. , Lasch Jon G. , Norman Nicholas C. , Pakulski Marek 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1493. DOI:10.1002/anie.198314930
Synthesis and Structure of [Na(tmeda)2]⊕[HNi2(C2H)4]⊕
Authors: Pörschke Klaus Richard , Kleimann Wolfgang , Wilke Günther , Claus Karl Heinz , Krüger Carl 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1527. DOI:10.1002/anie.198315270
Disulfur and Diselenium as Strong Acceptor Ligands in (η5‐C5H5)Re(CO)2S2 and [η5‐C5(CH3)5]Mn(CO)2Se2
Authors: Herberhold Max , Reiner Dietmar , Thewalt Ulf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1343. DOI:10.1002/anie.198313430
Photochemical Hole Burning: A Spectroscopic Study of Relaxation Processes in Polymers and Glasses
Authors: Friedrich Josef , Haarer Dietrich 
Published: December 2003

AbstractPhotochemical hole burning is a special type of saturation spectroscopy in the optical domain having many analogies with NMR methods. The holes, which are burnt with laser irradiation, appear as small indentations in the absorption spectra of dye molecules which are doped into a polymer or glass in minute concentrations. Based on their narrow line width, photochemical holes can be regarded as highly sensitive spectroscopic probes. They can be used to detect small perturbations of the system by external parameters, giving rise to line‐shifts and broadenings. Besides the many well documented, spectroscopic applications of hole burning, it may offer interesting future developments for the spectroscopy of biomolecules and for high‐density data storage.
ENDOR Spectroscopy — A Promising Technique for Investigating the Structure of Organic Radicals
Authors: Kurreck Harry , Kirste Burkhard , Lubitz Wolfgang 
Published: December 2003

AbstractThe name “ENDOR” has been known since biblical times and denotes a small town close to the Sea of Galilee (ca. 1000 B.C., 1 Sam. 28 : 7 ff). The acronym “ENDOR” (Electron Nuclear DOuble Resonance) characterizes the extension of electron spin resonance to electron‐nuclear double resonance spectroscopy, a method that has opened up new dimensions for the investigation of complicated paramagnetic molecules. Only ENDOR spectoscopy, which has achieved technical perfection in the last decade, overcomes the resolution limitations of EPR spectroscopy, thus allowing interesting applications in the field of biochemistry. ENDOR investigations of the primary process of photosynthesis, of the mode of action of derivatives of vitamin E and K, and of the mechanism of the enzymatic catalysis of flavoenzymes in biological redox‐chains have opened up new vistas. ENDOR and its extension to the triple resonance experiment TRIPLE offer, for example, the potential for a precise determination of hyperfine coupling constants, including their signs, which are frequently especially interesting. In addition to protons, a multiple of magnetic nuclei can be studied by ENDOR, such as e.g. 2H, 13C, and 14N. The ENDOR techniques is not restricted to monoradicals, but can also be applied to polyradicals in spin states of higher multiplicities (triplet, quartet, or quintet state). The experimental data accessible from ENDOR yield information about spin and charge density distributions, and about the geometrics of radicals and their internal dynamics; they also provide an excellent test for the accuracy of quantum mechanical calculations.
Liquid Crystals: A Tool for Studies on Chirality
Authors: Solladié Guy , Zimmermann Richard G. 
Published: December 2003

AbstractNematic liquid crystals are extremely sensitive to optically active molecules, which, at very low concentration, convert them into cholesteric liquid crystals. The purpose of this report is to review recent applications of liquid crystals to chirality studies. A brief discussion of the structure and properties of liquid crystals is followed by a survey of the methods currently being employed for the determination of the pitch and handedness of cholesteric liquid crystals. Of special interest in the formation of induced‐cholestric phases are the twisting powers of optically active compounds and the structural relationships between dopants and nematics. Liquid crystals can be used, inter alia, for the detection of small optical activities and for the determination of thermal racemization barriers and absolute configurations.
Modelling the Chemistry of Zeolites by Computer Graphics
Authors: Ramdas Subramaniam , Thomas John M. , Betteridge Paul W. , Cheetham Anthony K. , Davies E. Keith 
Published: December 2003

AbstractThe unique structural, adsorptive, and catalytic properties of zeolites are particularly amenable to illustration by computer (especially color) graphics. The siting of cations, the accommodation of guest reactant or product species, as well as the occurrence of various kinds of intergrowths (e.g. twin planes and coincidence boundaries) within these microporous solids can all be effectively portrayed by graphical means in such a manner as to emphasize the shape‐selective character of the host zeolite. The dynamics of translational and angular motion of guest species (for example benzene) in a channel of molecular dimensions within a typical zeolitic solid (for example silicalite) can also be probed interactively using appropriate potential functions.
Cyclic Voltammetry—“Electrochemical Spectroscopy”. New Analytical Methods (25)
Authors: Heinze Jürgen 
Published: December 2003

AbstractPolarography is still the best known classical measuring method in electroanalytical chemistry. However, in recent years its position has been challenged by cyclic voltammetry (CV). Simple diagnostic criteria and relatively easily acquired measuring techniques have hastened this development. Cyclic voltammetry has the further attraction of providing information not only on the thermodynamics of redox processes but also on the kinetics of heterogeneous electron‐transfer reactions and coupled chemical reactions. The characteristic shapes of the voltammetric waves and their unequivocal position on the potential scale virtually fingerprint the individual electrochemical properties of redox systems. For this reason the method has been labeled “electrochemical spectroscopy”.
Chemical Basis of the Action of Glyoxalase I, an Anticancer Target Enzyme
Authors: Douglas Kenneth T. , Shinkai Seiji 
Published: December 2003

AbstractAlthough glyoxalase I was discovered in 1913 the physiological role of this ubiquitous enzyme is still far from clear. It catalyzes the reaction of α‐ketoaldehydes and glutathione to produce S‐D‐lactoylglutathione, from which D‐lactate and glutathione are produced by glyoxalase II. Argument raged for many decades about the nature of the natural substrate. Was it methylglyoxal? Was methylglyoxal ever formed metabolically or was it purely artifactual? Some of these questions have been resolved in that a number of metabolic processes which produce α‐ketoaldehydes have now been recognized. Equally unsuccessful have been attempts to ascribe a physiological role to glyoxalase. This is clearly an important question since glyoxalase I occurs in cells at all levels of evolution. Time and time again glyoxalase I has been claimed to be linked to cancer, and a number of research groups worldwide are using it as a model for designing potential anticancer drugs. In this review article the mechanism of action of the enzyme is discussed, knowledge of which enables stronger inhibitors to be synthesized. Until roughly ten years ago when powerful NMR techniques were used to study it for the first time, it was assumed that the key step in the mechanism was a hydride ion transfer. Today, the mechanism is envisaged as a proton transfer.
High‐Resolution X‐ray Crystallography—An Experimental Method for the Description of Chemical Bonds
Authors: Angermund Klaus , Claus Karl Heinz , Goddard Richard , Krüger Carl 
Published: December 2003

AbstractBy increasing the accuracy of an X‐ray analysis, results are obtained which allow one to beyond the location of hydrogen atoms and say something about the distribution of electrons in molecules. Using several examples from organic and organometallic chemistry, the methods, problems, and results of this approach are described.