다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

Silver nanoparticles as a new generation of antimicrobials.

In the last few years the analysis of molecular crystal structures using tools based on Hirshfeld surfaces has rapidly gained in popularity. This approach represents an attempt to venture beyond the current paradigm—internuclear distances and angles, crystal packing diagrams with molecules represented via various models, and the identification of close contacts deemed to be important—and to view molecules as “organic wholes”, thereby fundamentally altering the discussion of intermolecular interactions through an unbiased identification of all close contacts.

Hirshfeld surface analysis

1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

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Chemical Redox Agents for Organometallic Chemistry

Green chemistry and the health implications of nanoparticles

MOLECULAR complexation of fullerenes in host–guest complexes has the potential to afford efficient large-scale purification of fullerenes1. This method would avoid the losses inherent in the chromatographic techniques currently in use, which arise from irreversible absorption on the stationary phase2. Several host-guest interactions have been reported for C60, including the formation of complexes with 1,4-hydroquinone3,4, azacrown compounds5, certain water-soluble macrocycles such as γ-cyclodextrin6–8, and complexation between C60 and an iridium phosphine in which pendant groups attached to a phosphorus atom form a cradle for an adjacent C60 molecule9. Other relevant studies are the inclusion of C60 into a microporous aluminophosphate10 and the formation of a charge-transfer complex between C60 and a thiafulvalene11. Here we show that both C60 and C70 will form discrete complexes with calixarenes, bowl-shaped macrocycles with hydrophobic cavities. Complexation of p-Bu'-calix[8]arene with a mixture of the toluene extract of 'crude' fullerene soot, followed by a series of recrystallizations, affords >99.5% pure C6. Our approach could lead to a substantial reduction in the cost of purifying C60 and C70.

Purification of C60 and C70 by selective complexation with calixarenes

Recent advances in solventless organic reactions: towards benign synthesis with remarkable versatility

The concept of an organic reaction between two macroscopic solid particles is investigated. Thus, we study several reactions that have been recently reported to proceed “in the solid phase” and clearly show that, in most cases, grinding the two solid reactants together results in the formation of a liquid phase. This is true both for catalytic transformations (e.g., aldol condensations and oligomerization of benzylic compounds) and for noncatalytic reactions (Baeyer−Villiger oxidations, oxidative coupling of naphthols using iron chloride, condensation of amines and aldehydes to form azomethines, homo-etherification of benzylic alcohols using p-toluenesulfonic acid, and nuclear aromatic bromination with NBS). This liquefaction implies the existence of a eutectic mixture with Tfusion below ambient temperature (although both reagents have higher than ambient melting points). In cases where heating is required, it is again clear that a phase change (from solid to liquid) occurs, explaining the observed reacti...

Understanding Solid/Solid Organic Reactions

Organic chemistry is continually evolving to improve the syntheses of value added and bioactive compounds. Through this progression, a concomitant advancement in laboratory technology has occurred. Many researchers now choose to mediate transformations in continuous-flow systems given the many benefits over round bottom flasks. Furthermore, reaction scale up is often less problematic as this is addressed at the inception of the science. Although single-step transformations in continuous-flow systems are common, multi-step transformations are more valuable. In these systems, molecular complexity is accrued through sequential transformations to a mobile scaffold, much like an in vitro version of Nature's polyketide synthases. Utilizing this methodology, multi-step continuous-flow systems have improved the syntheses of active pharmaceutical ingredients (APIs), natural products, and commodity chemicals. This Review details these advancements while highlighting the rapid progress, benefits, and diversification of this expanding field.

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Colin L. Raston

Papers

Green chemistry and the health implications of nanoparticles

Purification of C60 and C70 by selective complexation with calixarenes

Recent advances in solventless organic reactions: towards benign synthesis with remarkable versatility

Understanding Solid/Solid Organic Reactions

Multi-step continuous-flow synthesis.