Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

[*] Dr. S. Narayan, Dr. J. Muldoon, Prof. M. G. Finn, Prof. V. V. Fokin, Prof. H. C. Kolb, Prof. K. B. Sharpless Department of Chemistry and the Skaggs Institute of Chemical Biology The Scripps Research Institute 10550 North Torrey Pines Road La Jolla, CA 92037 (USA) Fax: (+ 1)619-554-6738 E-mail: sharples@scripps.edu [**] We thank Dr. Vladislav Litosh for carrying out preliminary work. Support from the National Institutes of Health, National Institute of General Medical Sciences (GM 28384), the National Science Foundation (CHE9985553), the Skaggs Institute for Chemical Biology, and the W. M. Keck Foundation is gratefully acknowledged. S.N. thanks the Skaggs Institute for a postdoctoral fellowship. We also thank Dr. Suresh Suri, Edwards Air Force Base, California, for a generous gift of quadricyclane. We urge our fellow chemists to float their problematic reactions on water and to send observations of success or failure to us at onwater@scripps.edu for public dissemination with attribution. Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. Angewandte Chemie

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200462883

“On Water”: Unique Reactivity of Organic Compounds in Aqueous Suspension

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Molecular Clusters of π-Systems: Theoretical Studies of Structures, Spectra, and Origin of Interaction Energies

Low dosage hydrate inhibitors (LDHIs) are a recent and alternative technology to thermodynamic inhibitors for preventing gas hydrates from plugging oil and gas production wells and pipelines. LDHIs are divided into two main categories, kinetic inhibitors (KHIs) and anti-agglomerants (AAs), both of which are successfully being used in field applications. This paper reviews the research and development of LDHIs with emphasis on the chemical structures that have been designed and tested. The mechanisms of both KHIs and AAs are also discussed.

History of the Development of Low Dosage Hydrate Inhibitors

Size-selected synthesis of metal nanoparticles by using electrospray in a liquid medium

Molecular clustering inherent in the liquid state: Effect of relativity in intermolecular interaction energy

The exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) formed by cerium(III) or samarium(III) ion and an organophosphorous ligand has been studied. The CPs exhibit distinctive Ln(3+) affinity that varies with a small change in its framework, depending on the central Ln(3+).

Tunable Selectivity of Lanthanide Ion Exchange within a Coordination Polymer

Against a backdrop of increasing demand, the recovery of neodymium (Nd) and especially dysprosium (Dy) from manufacturing scraps and used magnets has necessitated the development of Nd/Dy separation technologies. To this end, we suggest a simple and environmentally friendly separation method by fractional precipitation of coordination polymers (CPs)—extended complexes of metal ions and organic ligands. With the di(2-ethylhexyl) phosphoric acid ligand functioning as a precipitant, Dy was exclusively precipitated as a CP due to its precipitation equilibrium that is considerably different from that of Nd.

Environmentally friendly separation of dysprosium and neodymium by fractional precipitation of coordination polymers

Electrospraying is an electrochemical technique in which fine droplets are generated in the balance of electrostatic repulsion and surface tension. In this paper, we applied electrospray in the liquid phase in a new reactor system in which positively and negatively charged fine droplets collided with each other between two electrospray nozzles submerged in a solvent. When the hydrolysis of alkylchlorosilanes was carried out using this reactor, not only did the reaction rates increase, but also, the product distribution changed: the kinetically favored cyclotrimer was predominantly formed over the thermodynamically favored cyclotetramer. The yield of cyclotrimer increased with an increase in the voltage between the needles. Since the droplet size decreases with an increase in the applied voltage, the result suggests that the formed cyclotrimer could diffuse into the solvent before it was converted to the thermodynamically favored cyclotetramer.

Akihiro Wakisaka

Papers

Size-selected synthesis of metal nanoparticles by using electrospray in a liquid medium

Molecular clustering inherent in the liquid state: Effect of relativity in intermolecular interaction energy

Tunable Selectivity of Lanthanide Ion Exchange within a Coordination Polymer

Environmentally friendly separation of dysprosium and neodymium by fractional precipitation of coordination polymers

A Reactor System Using Electrospray in the Liquid Phase and Its Application in Selective Cyclosiloxane Synthesis