Angewandte Chemie International Edition

Michelle Livings3 October 2010

Covalent Layer-by-Layer Assembly and Solvent Memory of Multilayer Films from Homobifunctional Poly(dimethylsiloxane)

16 August 2010, Volume 49, Issue 35, pp 6116-6119

A simple procedure was used for the covalent layer-by-layer assembly of homobifunctional H2N-poly(dimethoxysilane)-NH2 on SiO2 surfaces that leads to robust layer-by-layer films of optical quality (see picture; photo on left) despite the use of non-purified commercial starting materials. The films show a solvent memory for swelling and de-swelling when immersed in the corresponding solvent for each polymer.

Bioinspired Self-Healing Superhydrophobic Coating

16 August 2010, Volume 49, Issue 35, pp 6129-6133

Self-healing superhydrophobic coatings are fabricated by preserving healing agents of reacted fluoroalkylsilane in layered polymeric coatings that are porous and rigidly flexible. When the top layer of fluoroalkyl chains decomposes or the coatings are scratched, the healing agents migrate to the surface to restore the superhydrophobicity of the coatings (see picture).

Reduction of a Metal-Organic Framework by an Organometallic Complex: Magnetic Properties and Structure of the Inclusion Compound [(η5-C5H5)2Co]0.5@MIL-47(V)

16 August 2010, Volume 49, Issue 35, pp 6212-6215

The stoichiometric reduction of the MIL-47(V) framework (see picture; green VO6 octahedra) was performed using cobaltocene as an organometallic reducing agent. The formation of a mixed-valence compound with a V3+/V4+ ratio of 1:1 was confirmed by magnetic susceptibility measurements. Incorporation of cobaltocene into the MIL-47(V) framework can be reversed upon treatment with water.

BioMOFs: Metal-Organic Frameworks for Biological and Medical Applications

23 August 2010, Volume 49, Issue 36, pp 6260-6266

A tremendous number of drugs have been developed but not applied further owing to poor bioavailability. To solve this problem, stable nontoxic metal–organic frameworks have been developed as drug-delivery vehicles and even as bioactive species in their own right.

High Performance Langmuir-Blodgett Monolayer Transistors with High Responsivity

23 August 2010, Volume 49, Issue 36, pp 6319-6323

Molecular field-effect transistors with bulk-like carrier mobility (as high as 0.04 cm2 V−1  s−1), high on/off current ratios (over 106), and high responsivity are formed by the integration of Langmuir–Blodgett techniques with sophisticated micro/nanofabrication. The transistors are formed from self-assembled uniform monolayers of copper phthalocyanine (CuPc) semiconductors and single-layer graphene as planar contacts.

Regulation of a Real-Time Self-Healing Process in Organogel Tissues by Molecular Adhesives

23 August 2010, Volume 49, Issue 36, pp 6338-6342

The thixotropic processes that occur in a naphthalenediimide-based organogel can be imaged in real time by TEM and AFM (see picture). The self-assembled 1D fibers disintegrate under mechanical stress and undergo a self-healing process during a resting time to reconstitute the 1D fibers.

Innovative Inorganic-Organic Nanohybrid Materials: Coupling Quantum Dots to Carbon Nanotubes

23 August 2010, Volume 49, Issue 36, pp 6425-6429

Covalent bonds (peptide condensation) and noncovalent interactions (π–π stacking) have been employed en route toward versatile donor–acceptor inorganic–organic nanohybrids, QD-pyrene/SWNT. A charge-transfer event within the hybrid transforms the excitonic state of the quantum dot into a charge-transfer state that has a lifetime of several nanoseconds.

Towards Understanding the Catalytic Reforming of Biomass in Supercritical Water

23 August 2010, Volume 49, Issue 36, pp 6434-6437

The function of a working ruthenium catalyst during the reforming of ethanol in supercritical water was studied in situ using X-ray absorption spectroscopy (see picture). The reforming of ethanol over a supported ruthenium catalyst in sub- and supercritical water is suggested to proceed by the same mechanism as steam reforming at low pressures.

Supramolecular Control of Stiffness and Strength in Lightweight High-Performance Nacre-Mimetic Paper with Fire-Shielding Properties23 August 2010, Volume 49, Issue 36, pp6448-6453

Hard/soft core/shell colloidal building blocks allow large-scale self-assembly to form nacre-mimetic paper. The strength and stiffness of this material can be tailored by supramolecular ionic bonds. These lightweight biomimetic materials show excellent and tunable mechanical properties and heat and fire-shielding capabilities.

A Graphene Oxide-Organic Dye Ionic Complex with DNA-Sensing and Optical-Limiting Properties3 September 2010, Volume 49, Issue 37, pp 6549-6553

A charge-transfer complex between graphene oxide (GO) and pyrene dye PNPB has been synthesized by a simple ion-exchange process. Its highly specific interactions with DNA compared to other biomolecules (see scheme) allows selective and rapid detection of DNA in biological mixtures. It also exhibits broadband optical limiting.

Water-Soluble Supramolecular Polymerization Driven by Multiple Host-Stabilized Charge-Transfer Interactions3 September 2010, Volume 49, Issue 37, pp 6576-6579

A supramolecular polymer with a high degree of polymerization has been constructed on the basis of multiple host-stabilized charge-transfer interactions (see picture; DADV is a dianthracenyl bis(bipyridinium bromide), CB[8]=cucurbit[8]uril). Through interactions between supramolecular polymer chains, a reversible gel can also be obtained.

One-Step Conversion of Aromatic Hydrocarbon Bay Regions into Unsubstituted Benzene Rings: A Reagent for the Low-Temperature, Metal-Free Growth of Single-Chirality Carbon Nanotubes3 September 2010, Volume 49, Issue 37, pp 6626-6628

The controlled chemical synthesis of uniform, single-walled carbon nanotubes from short hydrocarbon templates, such as aromatic belts and geodesic nanotube end-caps, by a Diels–Alder cycloaddition/rearomatization strategy requires a potent “masked acetylene” capable of transforming hydrocarbon bay regions into new unsubstituted benzene rings in a single operation. Nitroethylene has been found to effect such benzannulations (see scheme).

Ionic Liquids as Versatile Precursors for Functionalized Porous Carbon and Carbon-Oxide Composite Materials by Confined Carbonization

3 September 2010, Volume 49, Issue 37, pp 6664-6668

Thermolysis of an ionic liquid (IL) gives no char residue, whereas heating the same IL trapped within an oxide framework affords high carbonization yields (see picture). This confinement method allows incorporation of heteroatoms from the parent IL in the final products, for the development of functionalized porous carbon and carbon–oxide composite materials.