bluuebunny/crossref_metadata_2025_split huggingface dataset:
Main Group Carbenes
Authors: Carmalt Claire J. 
Published: December 2011

AbstractThis article describes the chemistry of main group carbene complexes. Although not limited to, the article particularly summarizes the coordination of N‐heterocyclic carbenes to main group species. Usually, carbene ligands cannot be stabilized by electron‐poor coordination fragments because traditional carbenes show a pronounced tendency toward metal‐to‐ligand π back‐donation. However, N‐heterocyclic carbenes do not rely on back‐donation for stabilization because of the delocalization of the nitrogen lone pair in these carbenes. Thus, they are able to form stable complexes with metals that normally show no tendency for π back‐donation. In general, the carbene acts as a two‐electron donor ligand in a similar fashion to phosphines.Carbene complexes of the alkali and alkaline earth metals, which show a preference for σ‐bonding, are described. The high nucleophilicity of the N‐heterocyclic carbenes is shown by alane, gallane, and indane complexes that have much greater stability than normally observed for Lewis base adducts of group 13. Nucleophilic carbenes also react with Lewis acidic group 14 complexes with the formation of neutral or ionic compounds via simple adduct formation or displacement of a halide ion. Furthermore, N‐heterocyclic carbenes are sufficiently nucleophilic to enable depolymerization of cyclopolyphosphines and cyclopolyarsines to occur with the isolation of carbene–pnictinidene adducts. These carbenes can also form stable adducts with strong electron acceptors, such as pnictogen pentafluorides, if the reactivity is moderated. In addition, stable chalcogen–carbene and halide–carbene complexes are also discussed.
Copper Proteins with Type 2 Sites
Authors: McGuirl Michele A. , Dooley David M. 
Published: December 2011

AbstractThe copper enzymes covered in this article span a wide range in terms of both their structural and reactivity properties. Yet the copper centers in each share similar coordination geometries and have been designated ‘Type 2 (or II)’ copper proteins. Type 2 copper proteins lack the unique spectroscopic or magnetic signatures that typify the so‐called Type 1 and Type 3 copper proteins, and the unique tetranuclear cluster found in nitrous oxide reductase. Indeed, the basis for classifying proteins as Type 2 was that the EPR (Electron Paramagnetic Resonance) spectra of the oxidized (resting) forms of these proteins closely resembled the spectra of ‘normal’ tetragonal CuIIcomplexes, withg∥ > g⊥ > 2.00, andA∥ ≥ 120 G at X‐band. It was generally surmised that the coordination environments of the copper sites in such enzymes were unexceptional, with five‐ or six‐coordinate structures composed of N, O ligands. As is often the case in science, many fascinating and totally unexpected structural and chemical phenomena turned out to be concealed behind this deceptively ‘normal’ facade. Each of the Type 2 enzymes covered here (superoxide dismutase, amine oxidase, lysyl oxidase, galactose oxidase, dopamine‐β‐monooxygenase, peptidylglycine α‐hydroxylating monooxygenase, and quercetinase) displays unique active‐site properties. Elucidating and elaborating structure/function relationships for these enzymes has been greatly aided by the availability of high‐resolution crystal structures for one or more enzymes from each group. These have generally corroborated the fairly detailed structural models that were developed from extensive spectroscopic studies. At the same time, the 3D structures have revealed many surprising details of the active sites. Indeed, the roles of copper in these ‘normal’ Type 2 copper centers are more diverse than ever imagined.
Copper Enzymes in Denitrification
Authors: Dooley David M. , Chan Jeannine M. 
Published: December 2011

AbstractDenitrification is an intrinsic part of the global nitrogen cycle, balancing the cycle by returning fixed nitrogen to the atmosphere. During denitrification, a bacterial respiratory process, nitrate or nitrite is reduced to nitrogenous oxides. All of the redox reactions of denitrification are catalyzed by metalloenzymes, two of which contain copper. This chapter reviews the structures, mechanisms, and assembly of these copper‐containing enzymes, copper nitrite reductase and nitrous oxide reductase.
Beryllium: Inorganic Chemistry
Authors: Keizer Timothy S. , McCleskey T. Mark 
Published: December 2011

Abstract
The speciation and molecular interactions of beryllium have remained relatively unexplored compared to most metals, despite its high toxicity and extensive use in industry. One reason for this fact is the difficulty in characterizing beryllium species in solution. Herein, the chemistry of beryllium, and its interaction with hydroxo, inorganic and organic ligands are discussed. The structure and formation of beryllium species are communicated with emphasis on the stability of species in solution.
Sol–Gel Encapsulation of Metal and Semiconductor Nanocrystals
Authors: Petruska Melissa A. , Klimov Victor I. 
Published: December 2011

Abstract
The ability to encapsulate nanocrystals in glass matrices affords the opportunity to fabricate a variety of robust materials exhibiting properties tunable with the size, shape, or composition of the dopant. Among the various methods to these composites, sol–gel processing has the distinction of being a ‘wet chemistry’ approach, as it relies on high purity chemical reagents and mild reaction conditions to generate three‐dimensional metal‐oxide polymeric networks. Two general routes to noble metal and semiconductor nanocrystal‐sol–gel composites are explored. In one strategy, the synthesis of the nanocrystal occurs during the fabrication of the host matrix. This direct growth method has been investigated as an express route to nanocrystal‐doped glasses that typically involves the addition of metal salts to sol–gel precursors. Subsequent reduction or precipitation of the embedded metal salts, either with gases or other chemical reagents, leads to the formation of the desired nanocrystals. The second approach exploits the synthetic procedures already available for making high quality, crystalline nanoscale materials and focuses on a decoupled process in which the synthesis of the colloidal nanocrystals is independent of the fabrication of the composite network. In this way, the size, shape, and composition of the nanocrystals can be tailored for specific applications, promising a precise control over the dopant that is unavailable in the direct growth method. Improvements in these procedures have led to the preparation of uniformly dispersed nanocrystal‐sol–gel composites with high nanocrystal volume loadings and narrow nanocrystal size dispersities that have aroused considerable interest for their unique optical, catalytic, and electronic behaviors.
Inorganic Ring Systems
Authors: Haiduc Ionel 
Published: December 2011

AbstractInorganic rings of various types can be formed as a result of the broad range of bond types available. Cyclic structures formed by self‐assembly of molecular building units (tectons) are discussed in terms of supramolecular chemistry concepts. The formation of covalent rings can be understood in terms of combining various fragments (synthons) in which the central atoms can display various oxidation states, coordination numbers, and geometries, leading to a broad structural diversity of cyclic structures for a given composition of the ring skeleton (as illustrated for P2N2and Si2N2rings).
Perturbed Angular Correlations of γ‐rays (PAC) Spectroscopy
Authors: Hemmingsen Lars , Butz Tilman 
Published: December 2011

AbstractIn this article, we give an elementary introduction to the theory and applications of perturbed angular correlation of γ‐rays (PAC) spectroscopy. In most applications in bioinorganic and inorganic chemistry the nuclear quadrupole interaction (NQI) is measured, providing a spectroscopic fingerprint of the local electronic and molecular structure and dynamics at the PAC probe site. The focus is on selected illustrative applications of PAC spectroscopy in bioinorganic chemistry: (i) local structure at metal ion binding sites in the bacterial mercury sensor MerR; de novo designed proteins; alcohol dehydrogenase–pH dependence; carboxypeptidase A—crystalline state versus solution; and carboxypeptidase A–during the hydrolysis of substrate; (ii) trapping intermediates in reactions using rapid freeze quenching; (iii) in vivo experiments on Cd(II) binding to biomolecules in cyanobacteria; (iv) cooperativity of metal ion binding in multinuclear sites; (v) dynamics of protein folding; (vi) rotational diffusion of biomolecules as a tool to monitor protein–protein interactions; (vii) exchange dynamics; and (viii) internal dynamics in proteins.Examples from inorganic chemistry and solid state physics are included for cases where the information derived is different from that already presented in the examples from bioinorganic chemistry: (i) magnetic properties of metals; (ii) defects trapped by the impurity PAC probe atom; (iii) temperature and pressure dependence of the EFG in metals; (iv) amorphous metals, alloys and internal oxidation; (v) metal surfaces and interfaces; (vi) semiconductors; (vii) phase transitions; (viii) charge density waves in transition metal dichalcogenides; (ix) intercalation reactions in 2H‐TaS2; (x) structure and bonding; (xi) single crystal experiments.
Vibrational Spectroscopy
Authors: Dyer R. Brian , Woodruff William H. 
Published: December 2011

Abstract
The application of vibrational spectroscopy to the study of inorganic and bioinorganic structures and dynamics has a rich history. Recent advances in vibrational spectroscopic techniques have increased the utility of these methods. Time‐resolved methods in particular have benefited from advances in lasers and other enabling technologies. In this chapter we describe the application of both Raman and infrared methods to problems in inorganic chemistry, with a focus on bioinorganic systems. We also describe difference vibrational spectroscopy methods for the analysis of metal active sites within complex protein structures. We develop quantitative rules for the relationships between force constants and bond distances. Such relationships are useful for predicting bond distances for cases where it is difficult to measure them otherwise, such as for excited states of molecules. Finally, we review time‐resolved Raman and IR methods and their application to the study of the structures and dynamics of excited states and chemical reactions of inorganic systems.
Electronic Spectroscopy
Authors: Hughes Joseph L. , Krausz Elmars 
Published: December 2011

AbstractDevelopments in the ability of electronic spectroscopy to provide insights into the fundamental electronic structure, photophysical and/or photochemical processes in inorganic and bioinorganic systems are outlined. These are highlighted by a number of examples across a range of chemical and biochemical systems. Some fundamental constraints regarding the application of electronic spectroscopy to a wider range of chemical questions are identified, as well as both practical and intrinsic limitations associated with the processes of measurement. The ubiquitous phenomenon of spectral broadening in optical and UV spectroscopy is given particular attention and the important concept of homogeneous versus inhomogeneous broadening is highlighted. The overall focus is on absorption‐based spectroscopies of chromophores at variable and low temperatures in either glassy, crystalline, or protein environments. The utilization of some of the powerful emerging technologies such as tuneable laser sources or synchrotron sources, along with the very high efficiency charge coupled device (CCD) and semiconductor diode detectors that are now available, allows the rapid accumulation of high quality spectra of small samples as well as measurements in minimal actinic fluences.
Biomineralization: Peptide‐Mediated Synthesis of Materials
Authors: Rutledge Ryan D. , Wright David W. 
Published: December 2011

AbstractBiomineralization provides many examples of the ambient synthesis of materials. Often associated with these systems are peptide templates. Synthetically, these templates offer tunable entities that can be altered in ways that affect the resulting composition, size, and morphology of the desired material. The development of peptide‐display methods has aided in the expansion of this approach to include many types of abiological substances. Accordingly, this review focuses on the identification and use of peptides involved in the syntheses of a number of different types of materials (metal oxides, calcium carbonate, metallic nanostructures). Covering only the most recent of advances (2004–2007), we examine the control exhibited by peptides free in solution and the ability of researchers to address and alter that control. The effects demonstrated as a result of immobilizing the peptide on a nanostructured or biological surface are discussed. Finally, the future of biomimetic synthesis of nanomaterials is considered in an attempt to gauge where biomineralization is headed and what possibilities it might offer down the road.
Carbon Nanotubes and Nanocomposites for Electrical and Thermal Applications
Authors: Wang Wei , Lu Fushen , Veca Lucia Monica , Meziani Mohammed J. , Wang Xin , Cao Li , Gu Lingrong , Sun Ya‐Ping 
Published: December 2011

Abstract
The extraordinary electrical and thermal properties of individual carbon nanotubes have prompted predictions on their potentials for ultimately forming polymeric nanocomposites. A significant barrier for the predicted nanocomposites is the severe bundling and insolubility of carbon nanotubes. Chemical modification and functionalization have been demonstrated as being effective in the debundling and solubilization of carbon nanotubes for their homogeneous dispersion into polymer matrices for desired high‐quality nanocomposites. More elegant is the approach to use polymers that are structurally identical or maximally similar to the matrix polymers in the nanotube functionalization to ensure full compatibility of the functionalized nanotubes with the corresponding polymer matrix. Several representative examples are presented, along with discussion on the benefits and issues concerning the polymeric nanocomposites thus obtained. For superior electrical properties, there is experimental evidence suggesting that the nanotube dispersion in the polymer matrix plays an important role. More promising is the use of separated metallic carbon nanotubes for a much enhanced performance in conductive nanocomposites and in related applications, such as transparent conductive films. For highly thermal conductive polymeric nanocomposites, on the other hand, the feasibility of using carbon nanotubes to achieve the desired performance has yet to be convincingly demonstrated experimentally. Nevertheless, the available results do suggest significant effects of the nanotube dispersion and alignment on thermal conductivities of the nanocomposites.
Carbon Nanotubes, Single‐Walled: Functionalization by Intercalation
Authors: Shiozawa Hidetsugu , Pichler Thomas , Pfeiffer Rudolf , Kuzmany Hans 
Published: December 2011

Abstract
The article reviews recent progresses in functionalization of single‐walled carbon nanotubes (SWCNT). Detailed studies of electronic, chemical, and structural properties of intercalated and filled carbon nanotubes using state‐of‐the‐art spectroscopic and microscopic techniques are described. Intercalation with alkali metal allows one to fine tuned the electron‐doping level of SWCNT. A photoemission study of potassium intercalation compounds of SWCNT bundles unveils a transition of the metallic ground state of a SWCNT bundle from Tomonaga–Luttinger liquid state to Fermi liquid state. In turn, the filling of single‐walled carbon nanotubes with fullerenes and organic molecules facilitates a reality of nanochemistry using carbon nanotubes as a nanoreactor. A combined spectroscopic and microscopic investigation of the interconversion of encapsulated fullerenes and organic molecules unveils either a catalytic or a noncatalytic process for the inner‐tube growth from different filler precursors. Such encapsulated reactions vary the chemical status of filling material which eventually leads to a modulation of the doping level of the carbon nanotube host.
Carbon Nanotubes: Fluorinated Derivatives
Authors: Khabashesku Valery N. , Kuznetsov Oleksandr V. , Pulikkathara Merlyn X. 
Published: December 2011

AbstractOngoing extensive research on carbon nanotubes (CNTs) has been facilitated by unique physicochemical properties and wide opportunities the CNTs offer for the new field of nanotechnology. Recent studies have shown that for efficient use of the remarkable properties of CNTs, particularly in the design of multifunctional materials for engineering and biomedical applications, they need to be surface modified by attachment of functional groups for improving solubility, processing, and compatability with host materials. It has been shown that fluorination is an efficient way to modify and control the surface properties of CNTs. For instance, fluorine functional groups on the sidewalls of CNTs effectively assist in unroping the nanotube bundles and in dispersion in alcohols and other polar solvents. Weakness of the CF bond and solubility of fluorinated nanotubes (fluoronanotubes) provide an opportunity for the synthesis of a variety of nanotube derivatives by substitution of fluorine through wet chemistry methods. This approach has been applied to preparation of a series of amino, amide, hydroxyl, thiol, and carboxyl group‐terminated derivatives. The activated sidewall CC π bonds in fluoronanotubes also permit a solution‐phase chemistry leading to addition reactions of free radicals, carbenes, dienes, and other reactive molecules. Functional groups chemically attached to the CNTs effectively assist in the dispersion of CNTs in polymer matrices, crucial for nanocomposites fabrication. “Tailored” chemical modifications are particularly useful for creating multiple sites for covalent bonding of nanotubes to polymer matrices for the enhancement of mechanical properties of epoxy, polyethylene, polypropylene, and nylon. Fluorinated CNTs represent a new family of nanoscale fluorocarbon materials. They enable various applications of functionalized CNTs, derived from fluoronanotubes, particularly in nanocomposites, sensors, nanoelectronic devices, nanoengineered drug delivery systems, and nanolubricants.
Inorganic Nanotubes
Authors: Remškar Maja 
Published: December 2011

AbstractThe first synthetic inorganic nanotubes were reported in 1992, but owing to the simultaneous discovery of carbon nanotubes they attracted wide international attention only recently. They are distinguished by important peculiarities, from growth mechanisms to the various physical and chemical properties and possible applications. Further analogies to carbon nanotubes, fullerenes, nanobuds, and peapods are presented as the first hybrid inorganic nanotube structures, i.e., nanobuds and “mama” tubes. Their structural and morphological properties determining chemical stability and activity, transport properties, mechanics and interaction with other building blocks in composites are discussed in this article.
Nanocomposite Materials: Polyhedral Silsesquioxanes
Authors: Seifalian Alexander M. , Kannan Ruben Y. , Ghanbari Hossein , Bakhshi Raheleh 
Published: December 2011

AbstractThe unique properties of nanocomposites have revolutionized the field of materials science. Polyhedral oligomeric silsesquioxane (POSS) is one of the widely used nanostructured materials for the synthesis of hybrid nanocomposites. POSS nanocrystals have been incorporated as building blocks of controllable shapes into polymers to form hybrid materials exhibiting improved properties. A variety of polymerization techniques have been used in the preparation of POSS‐containing hybrids. Incorporation of POSS into polymers can result in substantial improvement in physical properties of the polymers, such as low dielectric constants, increased glass‐transition temperatures, low coefficient of thermal expansion, enhanced thermal stability, mechanical strength, as well as improved oxidation resistance and reduction in flammability, oxygen permeability, heat evolution, and viscosity during processing. The most interesting POSS‐polymer has been the development of POSS–poly(carbonate‐urea)urethane that is used in medical applications owing to its enhanced biocompatibility and antithrombogenesity. These composites are materials of choice in the fabrication of various cardiovascular devices, such as artificial heart valves, stent‐grafts, bypass grafts, microvascular beds, and other biomedical devices including breast implants, and as scaffolds for tissue engineering.
Supramolecular Materials: Assemblies Based on Square‐Complexation
Authors: James Stuart L. 
Published: December 2011

Abstract
Square complexation of metal ions has become a remarkably useful construction motif for the self‐assembly of discrete nanoscopic structures and infinite frameworks. This article covers developments in the area since 2004. Interesting new aspects of self‐assembly methodology include solvent and anion dependence, use of three‐coordinate centers, photolabilization, kinetically controlled assembly, heteroligand structures, and the first very large mesoscopic structures (>20 nm). Also, known types of large self‐assembled cages, mainly based on palladium(II) and platinum(II) have been developed as protective reaction nanovessels in which to observe unusual, even unprecedented, chemistry. Internal and external functionalization of known structure types is leading to rich internal and external supramolecular chemistry. For infinite frameworks, square complexation, not only at single metal ions but also dimetallic units, typified by the dimetal‐tetracarboxylate paddle‐wheel motif, has led to a family of structurally versatile and functionalizable microporous pillared‐layer frameworks. In common with all coordination framework types, those based on square complexation are being increasingly studied with regard to their dynamics, sorption behavior, and catalysis.
Nano/Microporous Materials: Metal‐Ion Sorption Materials
Authors: Hobbs David T. 
Published: December 2011

Abstract
This paper provides a literature review from 2004 to the present, summarizing studies evaluating the use of nanomaterials and microporous materials as sorbents for the separation of metal ions from aqueous solutions. Materials such as microporous titanosilicates, mesoporous silicas, metal oxide nanoparticles, and carbon nanotubes exhibit increased loading and removal kinetics for a variety of metal ions compared to conventional sorbent materials. Also, incorporation of functional groups into these materials has shown promise to provide enhanced selectivity for a variety of metal ions.
Gold Nanoparticles as Chemical Catalysts
Authors: Ma Zhen , Overbury Steven H. , Dai Sheng 
Published: December 2011

Abstract

Gold, often known as being
chemically inert
, has rich inorganic and organic chemistry. In particular, gold nanoparticles, either protected by organic ligands or supported on solid surfaces, have attracted wide attention for their applications in catalysis, electronics, nonlinear optics, and biology. In this article, we summarize some recent advances in the synthesis of supported gold catalysts from the perspective of inorganic materials chemistry. These advances include new methods used to load gold, to prepare functionalized supports, and to postdecorate supported gold catalysts. More recent advances in the use of nanoparticle supports and other ordered nanostructures in making supported gold catalysts are also highlighted, and a critical analysis of the status of the field is presented. From this review, it is hoped that the reader will get an impression that inorganic materials chemistry can contribute to the synthesis of novel gold catalysts with good catalytic performance.