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

Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1–3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the s...

Atomically Precise Colloidal Metal Nanoclusters and Nanoparticles: Fundamentals and Opportunities

Superoxide ion (O2•–) is of great significance as a radical species implicated in diverse chemical and biological systems. However, the chemistry knowledge of O2•– is rather scarce. In addition, numerous studies on O2•– were conducted within the latter half of the 20th century. Therefore, the current advancement in technology and instrumentation will certainly provide better insights into mechanisms and products of O2•– reactions and thus will result in new findings. This review emphasizes the state-of-the-art research on O2•– so as to enable researchers to venture into future research. It comprises the main characteristics of O2•– followed by generation methods. The reaction types of O2•– are reviewed, and its potential applications including the destruction of hazardous chemicals, synthesis of organic compounds, and many other applications are highlighted. The O2•– environmental chemistry is also discussed. The detection methods of O2•– are categorized and elaborated. Special attention is given to the f...

Superoxide Ion: Generation and Chemical Implications

The use of zero-valent iron for groundwater remediation and wastewater treatment: a review.

Engineered nanomaterials (ENMs) are now becoming a significant fraction of the material flows in the global economy. We are already reaping the benefits of improved energy efficiency, material use reduction, and better performance in many existing and new applications that have been enabled by these technological advances. As ENMs pervade the global economy, however, it becomes important to understand their environmental implications. As a first step, we combined ENM market information and material flow modeling to produce the first global assessment of the likely ENM emissions to the environment and landfills. The top ten most produced ENMs by mass were analyzed in a dozen major applications. Emissions during the manufacturing, use, and disposal stages were estimated, including intermediate steps through wastewater treatment plants and waste incineration plants. In 2010, silica, titania, alumina, and iron and zinc oxides dominate the ENM market in terms of mass flow through the global economy, used mostly in coatings/paints/pigments, electronics and optics, cosmetics, energy and environmental applications, and as catalysts. We estimate that 63–91 % of over 260,000–309,000 metric tons of global ENM production in 2010 ended up in landfills, with the balance released into soils (8–28 %), water bodies (0.4–7 %), and atmosphere (0.1–1.5 %). While there are considerable uncertainties in the estimates, the framework for estimating emissions can be easily improved as better data become available. The material flow estimates can be used to quantify emissions at the local level, as inputs for fate and transport models to estimate concentrations in different environmental compartments.

Global life cycle releases of engineered nanomaterials

Applications of ultrasound in the synthesis of nanomaterials, nanocomposites, and nanoforms of chemical compounds are reviewed here. Ultrasonic treatment is widely used to produce nanostructures/nanocomposites containing elemental metals, alloys, carbon nanoforms, metal oxides, salts, and coordination compounds, macrocycles, and polymers, as well as for obtaining nanoemulsions and nanogels. Nanocatalysts can be prepared or function more actively in conditions of ultrasonic irradiation, in particular, in the degradation of organic pollutants. Ultrasonically prepared nanomaterials are also applied for tumor treatments and drug delivery purposes.

Ultrasound in Nanochemistry: Recent Advances

The synthesis and characterization of supramolecular assemblies {C60[M3]4}∞ consisting of C60 and coinage metal pyrazolates [M3] (i.e., [(3,5-(CF3)2Pz)M]3, where Pz = pyrazolate and M = Au, Ag, and Cu) are reported. {C60[Cu3]4}∞, {C60[Ag3]4}∞ and {C60[Au3]4}∞ form isomorphous crystals. The [M3] moieties adopt a concave conformation to complement the convex C60 surface. They exist as dimers of trimers (i.e., hexanuclear [M3]2 units) that are held together by three close M···M metallophilic interactions at 3.1580(17), 3.2046(7), and 3.2631(7) A for copper, silver, and gold systems, respectively. The [M3]2 moieties surround each C60 in a tetrahedral fashion, while each [M3]2 is sandwiched by two C60 molecules to form a supramolecular 3D assembly.

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Coinage Metal Pyrazolates [(3,5-(CF3)2Pz)M]3 (M = Au, Ag, Cu) as Buckycatchers

The coordinative properties of synthetically modified carbohydrates to metal cations are reviewed. Such metal complexes are distinct, owing to the structural diversity of the ligands and coordination modes. The influences of complex-formation conditions on chemical properties of modified carbohydrates, as well as on organic reactions (especially diastereoselective ones), are examined. In addition, this manuscript demonstrates the practical importance of the coordination interactions.

Review: synthetically modified carbohydrates as ligands

Several methods for the synthesis of metal-free phthalocyanine (Pc or PcH2) and copper phthalocyanine (PcCu) from urea and phthalic anhydride, phthalimide, 1,3-diiminoisoindoline (1,3-D), and phthalonitrile have been studied. The results show that the nature of the solvent is the most important factor in the conventional chemical and direct electrochemical synthesis of the final products. Different routes for phthalocyanine preparation are discussed.

Boris I. Kharisov

Papers

Ultrasound in Nanochemistry: Recent Advances

Coinage Metal Pyrazolates [(3,5-(CF3)2Pz)M]3 (M = Au, Ag, Cu) as Buckycatchers

Review: synthetically modified carbohydrates as ligands

Electrosynthesis of Phthalocyanines: Influence of Solvent

Advanced Environmental Analysis: Applications of Nanomaterials