Cover Picture: Angew. Chem. Int. Ed. 15/2002

The cover picture shows the interior of a red‐figure kylix (440–430 BC, British Museum London) which shows the brilliant exploits of Theseus, the Greek mythology hero. In the center, Theseus is shown defeating the infamous Minataur within the labyrinth. On the right, the hero raises his hand against Sciron, below whom the turtle is visible. Next clockwise, are shown the bull of Marathon, the punishment of Sinis, the slaying of the sow Phaea, the battle of Cercyon, and finally the punishment of Procrustes. The labors of Theseus are no different from the accomplishments of today's synthetic chemists working in total synthesis. One such endeavor, the total synthesis of the CP molecules with its challenges, twists and turns, and dead‐ends, but also its rewards, is compared to the conquest of the Minotaur by Theseus in the Review by K. C. Nicolaou and P. S. Baran on p. 2678 ff.     

Cover Picture: Angew. Chem. Int. Ed. 16/2002

The cover picture shows the molecular modeling of a star‐shaped metallo‐supramolecular polymer and the schematic drawing of a linear analogue. These molecules are of great interest because of their unique properties. Metallo‐supramolecular polymers emerge by the well‐directed combination of polymers, the properties of which have dominated the development of materials in recent years, with supramolecular ligands, which have the ability to organize spontaneously and form unique structures on a molecular level, and transition‐metal ions, which, through their physical properties bring characteristic functionalities. The well‐known properties of the individual components allow the use of established methods, such as UV/Vis spectroscopy, NMR spectroscopy, and gel permeation chromatography for characterization. However, the combination also requires the application of new methods, such as analytical ultracentrifugation or MALDI‐TOF mass spectrometry. More about metallo‐supramolecular polymers based on bipyridine and terpyridine complexes can be found in the review by U. S. Schubert and C. Eschbaumer on p. 2892 ff.     

Cover Picture: Angew. Chem. Int. Ed. 6/2002

The cover picture shows the electric eel, Electrophorus electricus, a source for commercially available acetylcholinesterase. In an experiment described by K. B. Sharpless and M. G. Finn and co‐workers on pp. 1053–1057, a femtomolar inhibitor was assembled by the enzyme from a collection of building blocks containing azide and alkyne functional groups, shown floating in solution. The templated 1,3‐dipolar cycloaddition reaction, producing the inhibitor, is represented by the flare of light at the center of the image.     

Cover Picture: Angew. Chem. Int. Ed. 7/2002

The cover picture shows Cu₂(μ‐O)₂ and Fe₂(μ‐O)₂ complexes with the M₂(μ‐O)₂ diamond core motif (the core is shown bottom right, M=green and oxygen=red spheres) and a representative example of a non‐heme multimetal enzyme (hydroxylase component of methane monooxygenase, in the background). Although quite a familiar feature in high‐valent manganese chemistry, the M₂(μ‐O)₂ diamond core motif has only recently been found in synthetic complexes for M=Cu or Fe. Despite differences in electronic structures that have been revealed through experimental and theoretical studies, Cu₂(μ‐O)₂ and Fe₂(μ‐O)₂ cores exhibit analogously covalent metal–oxo bonding, and similar tendencies to abstract hydrogen atoms from substrates. Our understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu₂(μ‐O)₂ and Fe₂(μ‐O)₂ complexes. In particular, it has led to the development of new mechanistic notions about how non‐heme multimetal enzymes, such as, methane monooxygenase, fatty acid desaturase, and tyrosinase, may function in the activation of dioxygen to catalyze a diverse array of organic transformations. To find out more see the review by L. Que, Jr. and W. B. Tolman on p.1114 ff.     

Cover Picture: Angew. Chem. Int. Ed. 13/2002

The cover picture shows benzoborirene, the product of the crossed‐molecular‐beam reaction between benzene molecules and boron atoms, displayed above the three‐dimensional plot of the angular‐ and translational‐energy‐dependent flux of the benzoborirene molecules in the center‐of‐mass system. As the reaction conditions preclude secondary collisions, the intermediate initially formed from the reactive collision decays by ejection of a hydrogen atom. The structure of the benzoborirene depicted is based on a DFT computation, which, combined with results of highly accurate coupled‐cluster calculations has been used to assign the reaction product by comparing experimental and theoretical reaction energies. Details are described by R. I. Kaiser and H. F. Bettinger on p. 2350 ff.     

Cover Picture: Angew. Chem. Int. Ed. 9/2002

The cover picture shows adamantane‐2,6‐dione encapsulated within a hydrogen‐bonded capsule made up of four identical subunits. The ketone functionality of the guest molecule (CPK model, red) participates in the structural seam at each end of the capsule through bifurcated hydrogen bonds. Find out more about encapsulating complexes in the review by Rebek, Jr., et al. on p. 1488 ff.     

Cover Picture: Angew. Chem. Int. Ed. 20/2002

The cover picture shows a series of ¹⁹F NMR spectra taken every hour during the monitoring of a time‐course experiment after addition of 5′‐fluoro‐5′‐deoxyadenosine (5′‐FDA) to a cell‐free extract of Streptomyces cattleya. This bacterium has the unusual capacity to biosynthesise organofluorine compounds from inorganic fluoride. The ¹⁹F NMR spectra illustrate that 5′‐FDA is a true intermediate in the biosynthesis of fluoroacetate and 4‐fluorothreonine. Other intermediates such as fluoroacetaldehyde are also observed for the first time. In a separate experiment, inorganic fluoride was converted into fluoroacetate, thus indicating that all of the enzymes involved in the fluoroacetate biosynthesis pathway are active in the cell‐free extract. These experiments report the first cell‐free biotransformations of inorganic fluoride into fluoroacetate, the most ubiquitous organic fluorine natural product, and pave the way for a biotechnological approach to organofluorine synthesis. Full details are described by O'Hagan and co‐workers on p. 3913 ff.     

Cover Picture: Angew. Chem. Int. Ed. 12/2002

The cover picture shows the thermally induced shape‐memory effect for a covalently cross‐linked polymer network. The polymer in its temporary shape (cube, picture on top) is heated from room temperature up to 70°C. Within 60 seconds the sample recovers its memorized, permanent shape of a nearly planar foil (picture on top left). The visual change of the material from opaque to transparent is caused by the melting of crystallites of the switching segments. The scheme in the center of the picture illustrates the molecular mechanism of the shape‐memory effect. The shown polymer network, which is synthesized from poly(ε‐caprolactone)dimethacrylate as macromonomer, is one of the first polymer systems that have specifically been developed for applications in the biomedical field. The net points (black) determine the permanent shape while the crystallites (blue) stabilize the temporary shape. More on the current state and the potential of this technology can be found in the review by A. Lendlein and S. Kelch on p. 2034 ff.