There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Chitin and chitosan: Properties and applications

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

Today cross-cutting approaches, where molecular engineering and clever processing are synergistically coupled, allow the chemist to tailor complex hybrid systems of various shapes with perfect mastery at different size scales, composition, functionality, and morphology. Hybrid materials with organic–inorganic or bio–inorganic character represent not only a new field of basic research but also, via their remarkable new properties and multifunctional nature, hybrids offer prospects for many new applications in extremely diverse fields. The description and discussion of the major applications of hybrid inorganic–organic (or biologic) materials are the major topic of this critical review. Indeed, today the very large set of accessible hybrid materials span a wide spectrum of properties which yield the emergence of innovative industrial applications in various domains such as optics, micro-electronics, transportation, health, energy, housing, and the environment among others (526 references).

Applications of advanced hybrid organic–inorganic nanomaterials: from laboratory to market

5.4. Miscellaneous Examples 2295 5.4.1. Couplings with Other Catalysts 2295 5.4.2. The Use of Other Boron Reagents 2295 5.4.3. Related Coupling Reactions 2296 5.5. Summary 2297 6. Sonogashira Coupling 2297 6.1. Couplings with Pd Particles 2297 6.2. Studies with Immobilized Palladium Complexes 2299 6.3. Miscellaneous Examples 2301 6.4. Carbonylative Sonogashira Couplings 2302 6.5. Summary 2302 7. Stille Couplings 2302 7.1. Stille Coupling 2302 7.2. Carbonylative Stille Coupling 2304 7.3. Summary 2304 8. Miscellaneous Cross-Coupling Reactions 2304 9. Allylations 2305 9.1. Tsuji-Trost Allylation 2305 9.2. Allylation of Boron Reagents 2306 10. Homocouplings 2307 10.1. Summary 2308 11. C-C Couplings in Continuous Systems 2308 12. Conclusions and Outlook 2311 Author Information 2314 Biography 2314 References 2314

Efficient, selective, and recyclable palladium catalysts in carbon-carbon coupling reactions.

Heterogeneous oligomerization of ethylene over highly active and stable Ni-AlSBA-15 mesoporous catalysts

Interaction of chitosan with natural or synthetic anionic polyelectrolytes. 1. The chitosan–carboxymethylcellulose complex

Role of the pH on hyaluronan behavior in aqueous solution.

Magnetic chitosan composite particles: Evaluation of thorium and uranyl ion adsorption from aqueous solutions

Recent studies focus on the chemical modification of polysaccharides for biomedical applications. Guar gum is a natural polymer composed of linear chains of (1-4)-β-D mannopyranosyl units with α-Dgalactopyranosyl units attached by (1-6) linkages, in a ratio of about 1.5-2, possessing hydroxyl groups available for the attachment of biologically active compounds. The modifications here discussed include the introduction of carboxymethyl groups into the molecule, for extending the applications of partially carboxymethylated guar gum. The carboxymethylation conditions with respect to the volume and concentration of sodium hydroxide, weight of chloro-acetic acid and reaction temperature were optimized. The resulting products were characterized by NMR and FTIR spectroscopy and by thermal gravimetric analysis (TGA). The carboxymethylated guar gum may provide an efficient alternative approach for the oral delivery of hydrophilic macromolecules.

Marcel Popa

Papers

Heterogeneous oligomerization of ethylene over highly active and stable Ni-AlSBA-15 mesoporous catalysts

Interaction of chitosan with natural or synthetic anionic polyelectrolytes. 1. The chitosan–carboxymethylcellulose complex

Role of the pH on hyaluronan behavior in aqueous solution.

Magnetic chitosan composite particles: Evaluation of thorium and uranyl ion adsorption from aqueous solutions

Carboxymethylation of guar gum: synthesis and characterization