The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.

Nanomaterials in the environment: Behavior, fate, bioavailability, and effects

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Asymmetric 1,3-Dipolar Cycloaddition Reactions

One of the initial steps in the development of therapeutic agents is the identification of lead compounds that bind to the receptor or enzyme target of interest. Many analogs of these lead compounds are then synthesized to define the key recognition elements for maximal activity. In general, many compounds must be evaluated in both the lead identification and optimization steps. Increasing burdens have been placed on these efforts due to the large number of new therapeutic targets that continue to be identified thorough modern molecular biology methods.1 To address this demand, very powerful chemical and biological methods have been developed for the generation of large combinatorial libraries of peptides2 and oligonucleotides3 that are then screened against a receptor or enzyme to identify high-affinity ligands or potent inhibitors, respectively. While these studies have clearly demonstrated the power of library synthesis and screening strategies, peptides and oligonucleotides generally have poor oral activities and rapid in vivo clearance;4 therefore their utility as bioavailable therapeutic agents is often limited. Due to the favorable pharmacokinetic properties of many small organic molecules (<600-700 molecular weight),5 the design, synthesis, and evaluation of libraries of these compounds6 has rapidly become a major frontier in organic chemistry. Lorin A. Thompson was born in Lexington, KY, in 1970. He received the Bachelor of Science degree from the University of North Carolina, Chapel Hill, in 1992 where he worked under the guidance of Joseph Desimone. He is currently pursuing his doctorate in the laboratory of Jonathan Ellman at UC Berkeley where he is the 1994 Glaxo-Wellcome fellow. His research interests include the development of synthetic methodology for organic library construction.

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Synthesis and Applications of Small Molecule Libraries.

1,2-Amino Alcohols and Their Heterocyclic Derivatives as Chiral Auxiliaries in Asymmetric Synthesis

The benzylation of benzene and chlorobenzene with benzyl or p-chlorobenzyl chloride under the influence of various catalysts has been carried out in order to elucidate the relation between the cleavage reaction of the DPM and the Friedel-Crafts benzylation. In the aluminum chloride- or gallium chloride-catalyzed benzylation, the compositions of the equilibrium mixture are similar to those of the cleavage reaction. It has been suggested that, in the presence of such catalysts, the DPM formed at an initial stage is cleft with the catalyst, and that the same equilibrium relationship as has been postulated in the cleavage reaction is established. On the other hand, in the aluminum chloride-, gallium chloride-nitro compound complex or in indium chloride, which does not exhibit the ability to cleave the DPM, both the products and the isomer distributions are different. It has been estiablished that the isomer distributions in the benzylation are affected by the reactivity of the reactive species as well as by t...

Studies of Diarylalkanes. V. The Benzylation of Benzene and Chlorobenzene with Benzyl or p-Chlorobenzyl Chloride under the Influence of Various Catalysts

Fullerene derivative 2 carrying pyridinium cation bound to sonicated calf thymus DNA in water. The binding ratio was 1 fullerene unit to 1 phosphate residue, giving the complex where DNA strand is seemingly coated with electron-conducting fullerenes. Cyclic voltammetry shows three-step redox couples in the complex, and the current peaks were broadened and shifted to positive side as compared to uncomplexed 2. Binding of 2 onto grooves of DNA double helix was suggested.

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DNA coated with cationic fullerene derivative. A possible micro- wire in water

べンズアルデヒドアジン型芳香族アルダジン類およびアセトフェノンアジン型芳香族ケタジン類の質量スペクトルを測定し,フラグメントイオンおよび準安定ピークをもとにしてそれぞれのフラグメンテーションを考察した。そして電子衝撃によってアルダジン類の場合にはアリール基が1,4-,水素が1,3-転位,ケタジン類の場合にはアリール基,メチル基および水素が興味ある数種の転位方式をとって開裂することを明らかにした。また,ベンゾフェノン・ベンジリデンヒドラゾンおよびベンゾフェノンアジンのフラグメンテーションについても考察した。

Mass Spectra of Aromatic Aldazines and Ketazines

Synthesis of Heterocycles Using Silylmethyl Heterocumulenes

Enamines derived from cyclohexanone, propionaldehyde, and n-butyraidehyde and secondary amines react with pyrrole and pyrazole, affording new Michael type adducts respectively.

Otohiko Tsuge

Papers

Studies of Diarylalkanes. V. The Benzylation of Benzene and Chlorobenzene with Benzyl or p-Chlorobenzyl Chloride under the Influence of Various Catalysts

DNA coated with cationic fullerene derivative. A possible micro- wire in water

Mass Spectra of Aromatic Aldazines and Ketazines

Synthesis of Heterocycles Using Silylmethyl Heterocumulenes

Studies of enamines. vi. the additions of pyrrole and pyrazole to enamines