A scheme that reduces the calculations of ground-state properties of systems of interacting particles exactly to the solution of single-particle Hartree-type equations has obvious advantages. It is not surprising, then, that the density functional formalism, which provides a way of doing this, has received much attention in the past two decades. The quality of the energy surfaces calculated using a simple local-density approximation for exchange and correlation exceeds by far the original expectations. In this work, the authors survey the formalism and some of its applications (in particular to atoms and small molecules) and discuss the reasons for the successes and failures of the local-density approximation and some of its modifications.

The density functional formalism, its applications and prospects

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

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

The review covers the knowledge on photoremovable protecting
groups and includes all relevant chromophores studied in the
time period of 2000–2012; the most relevant earlier works are
also discussed.

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Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

The 1:1 molecular complexes between SO/sub 3/ and a series of oxygen-containing bases have been isolated and characterized in nitrogen matrices. The spectra of the complexes all showed a red shift and splitting of the antisymmetric stretching mode of the SO/sub 3/ subunit in the complex, typified by product bands at 1362 and 1378 cm/sup -1/ in the complex with dimethyl ether. A number of perturbed vibrational modes of the base subunit were observed as well, and generally arose from vibrations involving motion of the oxygen atom of the base. A comparison of the shift of the perturbed base modes in these complexes with previously studied complexes indicated that SO/sub 3/ is a very strong Lewis acid, although only small shifts were observed for the SO/sub 3/ subunit, and the symmetric stretching mode was not activated to a detectable degree.

Bruce S. Ault

Papers

Matrix isolation infrared spectra of the 1:1 molecular complexes of sulfur trioxide with selected oxygen-containing bases

Matrix isolation studies of the interaction of cyclopropane with strong lewis acids

Matrix isolation and theoretical study of the reaction of HSiCl3 and CH3OH: infrared spectroscopic characterization of Cl2HSiOCH3

Infrared, Raman, and ultraviolet spectra of M+ClF- species in solid argon

Matrix isolation study of the products and reactions pathways in the corona excited discharge of C6F6