Transition-metal-templated synthesis of rotaxanes and catenanes: From small molecules to polymers

This article provides an overview of the fundamental principles of the synthesis of metallocatenanes and metallorotaxanes. It also describes the synthesis and properties of electronic conducting polymers—polypyrrole and polythiophene—built around metallocatenanes and metallorotaxanes. The particular properties of this new class of polymers, including the possibility of transmetallation reactions being performed with them and the observation of electronic coupling between the metal centers and the conducting matrix, are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3470–3477, 2003     

Chiral coordination polymer as a luminescence sensor for small organic molecules

1. Download high-res image (178KB)
2. Download full-size image

     

Biotechnology and polymer chemistry: a growing relationship

DuPont is using biotechnology to make chemical compounds and materials, especially polymers and polymer intermediates ‐ demonstrating that biotechnology can lead to more effective and productive manufacturing processes for traditional chemical businesses as well as pharmaceuticals, agricultural products, and new products for improved nutrition and health.     

Stereocontrol in solid-phase radical reactions: radical addition to oxime ether anchored to polymer support

A high degree of stereocontrol in solid-phase radical reactions was achieved by using triethylborane and diethylzinc as a radical initiator at low reaction temperature. Alkyl radical addition to Oppolzer's camphorsultam derivatives of oxime ether anchored to polymer support proceeded smoothly to give the alpha-amino acid derivatives with excellent diastereoselectivities.     

Click chemistry as a macrocyclization tool in the solid-phase synthesis of small cyclic peptides

Despite the vast number of techniques developed for the cyclization of small peptides, cyclization efficiency remains problematic in peptides that lack turn-promoting structures. Here we demonstrate the utility of click chemistry as a macrocyclization tool in the solid-phase synthesis of cyclic tetra-, penta-, hexa-, and heptapeptides. On-resin cyclization is completed at room temperature within 6 h, resulting in predominantly monomer with small amounts of cyclomultimer byproducts.     

From synthetic organic chemistry to electrochemistry

The paper describes the change of the author??s research from synthetic organic chemistry to electrochemistry and the advantages and disadvantages of having been trained in organic synthesis rather than in electrochemistry. The described research in electrochemistry includes, among other projects, oxidations in non-aqueous solvents, reduction of azomethine derivatives and heterocyclic compounds, synthesis of heterocyclic compounds, reduction of graphite, electrocatalytic reductions, electron transfer in nucleophilic substitutions and additions, determination of redox potentials of short-lived radicals, and electrochemical formation of Grignard compounds having reducible groups. At the end, some considerations after 60?years of research are included.     

Redox-active ligands and organic radical chemistry

Knowledge about bonding in diiminepyridine (L) halide, alkyl, and dinitrogen complexes of the metals iron, cobalt, and nickel is summarized, and two new examples are added to the set: L(1)Ni(Me) and L(1)Ni(N(2)). Reactivity of these types of complexes is discussed in terms of organic radical chemistry. New C-C couplings with L(2)CoAr complexes are described and proposed to involve halide abstraction and radical coupling. Calculations support the high tendency of the diiminepyridine ligand to accept an electron coming from a metal-carbon bond and so facilitate loss of a radical.     

Diastereoselective solid-phase radical addition to oxime ether anchored to polymer support

Stereocontrol in radical reactions of oxime ether anchored to polymer support was studied. Highly diastereoselective solid-phase radical reaction was achieved by using triethylborane and diethylzinc as a radical initiator at low reaction temperature, providing a novel method for the synthesis of the alpha-amino acid derivatives with excellent diastereoselectivities.     

Electrochemically controlled transport of small charged organic molecules across conducting polymer membranes

The transport of a range of functionalised sulfonated aromatics across conducting polypyrrole membranes has been considered. In the course of these studies several unique aspects of the chemical selectivity of these conducting materials have been identified. Using electrochemical quartz crystal microbalance (EQCM) the ion-exchange behaviour of these membranes was investigated to further elucidate the transport mechanism.     

From smart polymer molecules to responsive nanostructured surfaces

A heteroarm star block copolymer made from seven polystyrene and seven poly(2-vinylpyridine) arms was grafted onto a solid substrate to fabricate a responsive polymer surface consisting of a densely packed monolayer of copolymer molecules. The grafted layer demonstrates a two-level hierarchical response upon external stimuli combining core-shell transitions of single stars with cooperative transitions of the interacting arms between "dimple" and "ripple" morphologies of the monolayer. The response allows for the switching of the surface properties upon changing solvent selectivity or pH of the aqueous environment.     

From cyclopentadiene to isoxazoline-carbocyclic nucleosides: a rapid access to biological molecules through nitrosocarbonyl chemistry

A rapid access to carbocyclic nucleosides containing a fused isoxazoline ring is proposed starting from cyclopentadiene. The route involves an hetero Diels-Alder cycloaddition reaction of nitrosocarbonylbenzene followed by a 1,3-dipolar cycloaddition of nitrile oxides, cleavage of the N-O tether and elaboration of the heterocyclic aminols into nucleosides via linear construction of purine and pyrimidine heterocycles.     

From high-spin organic molecules to organic polymers with magnetic ordering

This concept paper outlines the design of the first pi-conjugated organic polymer with magnetic ordering. This rational, "bottom-up" macromolecular design is based on synthesis and study of polyarylmethyl polyradicals with increasing number of exchange-coupled unpaired electron spins. The prospects for attaining organic polymer magnets with stability at ambient temperature and/or higher magnetic ordering temperatures will be discussed.     

The coordination chemistry of small sulfur-containing molecules: a personal perspective

The sulfur oxides SO, SO? and SO?, and thioformaldehyde H?C=S and its oxides H?C=SO and H?C=SO? form stable coordination compounds with a range of transition metals. The complexes have a rich chemistry which differs markedly from that of the free ligands. Typical reactions involve electrophilic additions, nucleophilic additions and cycloadditions. The complexes can be used as synthons to incorporate these small molecules as building blocks into larger structures.     

Early contributions to the chemistry of organic radical ions

The correct chemical composition and the true nature of organic radical ions were not recognized until well into the 20th century. Yet, the earliest observation of such a species as a colored transient dates back at least 150 years. Some pioneering reactions involving radical ions are discussed, and contributions to their understanding are reviewed.     

Characterizing the surface chemistry of nanoparticles: an analogy to solid-phase synthesis samples

Chemical modifications of nanoparticle's (NP's) surfaces can be used to regulate their activities, remove their toxic effects, and enable them to perform desired functions. Similar to SPS samples, modified NPs also have small-molecules on the surface of a solid support. The need to monitor synthesis, optimize reaction conditions, and characterize the products is quite similar in both situations. FTIR, NMR, MS and other analytical methods have been used as effective methods to analyze surface bound molecules and monitor organic reactions directly, or indirectly, on a solid phase of a resin or a NPs.     

Nitroxides: applications in synthesis and in polymer chemistry

This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.     

Adsorption of organic molecules on a melamine-modified porous polymer

Inverse gas chromatography in the infinite dilution regime was used to study the adsorp-tion of organic molecules on a micromesoporous styrene-divinylbenzene copolymer modified with melamine deposited onto its surface in amounts of 10^–6, 10^–5, 10^–4, 10^–3, 10^–2, and 5?10^–2 weight parts. Contributions of different intermolecular interactions and polarity of the samples to adsorption energy values were calculated using LFER and by Dong method. Contributions of methyl group to Helmholtz adsorption energy and to its dispersion compo-nent were determined. The polarity of the modified samples showed a non-linear dependence on the amount of the deposited modifier (pC): at 4 < pC < 6, it increases as the modifier concentration grows, abruptly falls at pC = 3, and does not change with the further decrease in pC. This is probably caused by the formation of melamine intermolecular associates at higher modifier concentrations.