Graphitic carbon nitride, g-C3N4, can be made by polymerization of cyanamide, dicyandiamide or melamine. Depending on reaction conditions, different materials with different degrees of condensation, properties and reactivities are obtained. The firstly formed polymeric C3N4 structure, melon, with pendant amino groups, is a highly ordered polymer. Further reaction leads to more condensed and less defective C3N4 species, based on tri-s-triazine (C6N7) units as elementary building blocks. High resolution transmission electron microscopy proves the extended two-dimensional character of the condensation motif. Due to the polymerization-type synthesis from a liquid precursor, a variety of material nanostructures such as nanoparticles or mesoporous powders can be accessed. Those nanostructures also allow fine tuning of properties, the ability for intercalation, as well as the possibility to give surface-rich materials for heterogeneous reactions. Due to the special semiconductor properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene, trimerization reactions, and also the activation of carbon dioxide. Model calculations are presented to explain this unusual case of heterogeneous, metal-free catalysis. Carbon nitride can also act as a heterogeneous reactant, and a new family of metal nitride nanostructures can be accessed from the corresponding oxides.

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Graphitic carbon nitride materials: variation of structure and morphology and their use as metal-free catalysts

Methods and compositions are described for immobilizing anti-ligands, such as antibodies or antigens, hormones or hormone receptors, oligonucleotides, and polysaccharides on surfaces of solid substrates for various uses. The methods provide surfaces covered with caged binding members which comprise protecting groups capable of being removed upon application of a suitable energy source. Spatially addressed irradiation of predefined regions on the surface permits immobilization of anti-ligands at the activated regions on the surface. Cycles of irradiation on different regions of the surface and immobilization of different anti-ligands allows formation of an immobilized matrix of anti-ligands at defined sites on the surface. The immobilized matrix of anti-ligands permits simultaneous screenings of a liquid sample for ligands having high affinities for certain anti-ligands of the matrix. A preferred embodiment of the invention involves attaching photoactivatable biotin derivatives to a surface. Photolytic activation of the biotin derivatives forms biotin analogs having strong binding affinity for avidin. Biotinylated anti-ligands can be immobilized on activated regions of the surface previously treated with avidin.

Spatially-addressable immobilization of anti-ligands on surfaces

Insofar as one of the fundamental objectives of organic synthesis is the construction of complex molecules from simpler ones, the importance of synthetic efficiency becomes immediately apparent and has been well-recognized.1 The increase in molecular complexity2 that necessarily accompanies the course of a synthesis provides a guide (and a measure) of synthetic efficiency. As a goal, one would like to optimally match the change in molecular complexity at each step with reactions of comparable synthetic complexity. Thus, the creation of many bonds, rings, and stereocenters in a single transformation is a necessary (though not sufficient) condition for high synthetic efficiency. The ultimate, perfect match would constitute single-step syntheses. More realistically, especially in view of the desire for general synthetic methods, the combination of mulScott E. Denmark was born in New York in 1953. He obtained an S.B. degree from MIT in 1975 and carried out research with Daniel Kemp and Richard Holm. His graduate studies at the ETH-Zurich with Albert Eschenmoser culminated with the D. Sc. Tech. degree in 1980. That same year he joined the faculty of the University of Illinois at UrbanasChampaign and was promoted to full professor in 1987. In 1991 he was named the Reynold C. Fuson Professor of Chemistry. His research interests are primarily in the invention of new synthetic reactions, structure and reactivity of organoelement reagents, and the origin of stereocontrol in fundamental carbon−carbon bond forming reactions.

Tandem [4+2]/[3+2] Cycloadditions of Nitroalkenes.

Iniferters are initiators that induce radical polymerization that proceeds via initiation, propagation, primary radical termination, and transfer to initiator. Because bimolecular termination and other transfer reactions are negligible, these polymerizations are performed by the insertion of the monomer molecules into the iniferter bond, leading to polymers with two iniferter fragments at the chain ends. The use of well-designed iniferters would give polymers or oligomers bearing controlled end groups. If the end groups of the polymers obtained by a suitable iniferter serve further as a polymeric iniferter, these polymerizations proceed by a living radical polymerization mechanism in a homogeneous system. In these cases, the iniferters (CS bond) are considered a dormant species of the initiating and propagating radicals. In this article, I describe the history, ideas, and some characteristics of iniferters and living radical polymerization with some iniferters that contain dithiocarbamate groups as photoiniferters and several compounds as thermal iniferters. From the viewpoint of controlled polymer synthesis, iniferters can be classified into several types: thermal or photoiniferters; monomeric, polymeric, or gel iniferters; monofunctional, difunctional, trifunctional, or polyfunctional iniferters; monomer or macromonomer iniferters; and so forth. These lead to the synthesis of various monofunctional, telechelic, block, graft, star, and crosslinked polymers. The relations between this work and other recent studies are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2121–2136, 2000

https://onlinelibrary.wiley.com/doi/epdf/10.1002/%28SICI%291099-0518%2820000615%2938%3A12%3C2121%3A%3AAID-POLA10%3E3.0.CO%3B2-X

Iniferter concept and living radical polymerization

Publisher Summary This chapter focuses on the electron transfer reactions in organic chemistry. The simplest elementary act in homogeneous solution chemistry is the exchange of an electron between two chemical entities. No bonds need to be formed or broken in the process, and if the two species are identical, except for a difference in oxidation state, no net chemical change takes place. Such self-exchange reactions constitute the basis of theoretical treatments of electron transfer. A more complex and chemically interesting situation is the electron-transfer reaction between two species of different chemical composition. In electron-transfer theory, it is an important postulate that electrons are transferred one by one, which does not mix well with the two-electron centered electronic theory of organic molecules. Organic electron transfers rarely occur as isolated steps because of the high chemical reactivity of odd-electron species. Processes involving one or several electron-transfer steps are not likely to preserve the stereochemical integrity of the reactants. With the present upsurge of research studies frequently invoking organic electron-transfer steps in mechanistic discussions, there is a great need of a theoretical background applicable to organic species and compatible with the language of physical organic chemistry.

Electron transfer reactions in organic chemistry

Various active methylene compounds were carboxylated by employing the reagent system, 1,8-diazabicyclo(5.4.0)-7-undecene and carbon dioxide, in organic solvents or without solvent at room temperature.

Carboxylation of active methylene compounds using the reagent of 1,8-diazabicyclo(5.4.0)-7-undecene and carbon dioxide

Novel Reactions of Iodosobenzene with Various Organic Compounds

Copper-iron-polyphthalocyanine shows catalytic activity on the oxidation of acetaldehyde ethylene acetal with oxygen at 30°C; this catalytic activity is remarkably dependent on the atomic ratio of copper to iron ions involved and on the activation energy of the electrical conductivity of copper-iron-polyphthalocyanine. The catalytic oxidation of acetaldehyde ethylene acetal with oxygen in the presence of copper-iron-polyphthalocyanine gives, selectively, ethylene glycol monoacetate as the main reaction product, together with small amounts of ethylene glycol diacetate, ethylene glycol, acetaldehyde, and acetic acid. This catalyst is also effective in the selective oxidation of cumene and benzaldehyde ethylene acetal.

Organic Catalysts. III. The Catalytic Action of Copper-Iron-Polyphthalocyanine on the Oxidation of Acetaldehyde Ethylene Acetal

The 1,3-dipolar cycloadditions of phenylglyoxylonitrile oxide, benzonitrile-N-phenylimine, or N-phenyl-C-p-nitrophenylnitrone to norbornadiene, 2,3-dicyanonorbornadiene, and 2,3-bis(methoxycarbonyl...

1,3-Dipolar Cycloadditions to Bicyclic Olefins. I. 1,3-Dipolar Cycloadditions to Norbornadienes

The nitrosation of dimethylphenacylsulfonium bromide (I) with sodium nitrite and hydrochloric acid in water gave 3,4-dibenzoyl-1,2,5-oxadiazole 2-oxide (II) in a 76% yield. The nitrosation of I in a similar manner in 1 : 1 dioxane-water afforded ω-chloro-ω-isonitrosoacetophenone (III) in an 80% yield. The treatment of III with triethylamine produced II through benzoylnitrile oxide (IX). 1,3-Dipolar cycloadditions of IX generated from III were conducted, using methyl methacrylate, styrene, acrylonitrile, and ethyl chloroformate as dipolarophiles, to yield the expected cycloadducts. The mechanisms of these reactions are discussed.

Eiji Imoto

Papers

Carboxylation of active methylene compounds using the reagent of 1,8-diazabicyclo(5.4.0)-7-undecene and carbon dioxide

Novel Reactions of Iodosobenzene with Various Organic Compounds

Organic Catalysts. III. The Catalytic Action of Copper-Iron-Polyphthalocyanine on the Oxidation of Acetaldehyde Ethylene Acetal

1,3-Dipolar Cycloadditions to Bicyclic Olefins. I. 1,3-Dipolar Cycloadditions to Norbornadienes

The Preparation and Reactions of Benzoylnitrile Oxide from Dimethylphenacylsulfonium Bromide