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The aza-Cope-Mannich reaction and ring-closing metathesis are key steps in the assembly of intermediates containing rings A−D of Daphniphyllumalkaloids of the daphnicyclidin type such as daphnipaxinin and oldhamine A. [ABSTRACT FROM AUTHOR]

Conversion cathodes represent a viable route to improve rechargeable Li + battery energy densities, but their poor electrochemical stability and power density have impeded their practical implementation. Here, we explore the impact cell fabrication, electrolyte interaction, and current density have on the electrochemical performance of FeS 2 /Li cells by deconvoluting the contributions of the various conversion and intercalation reactions to the overall capacity. By varying the slurry composition and applied pressure, we determine that the capacity loss is primarily due to the large volume changes during (de)lithiation, leading to a degradation of the conductive matrix. Through the application of an external pressure, the loss is minimized by maintaining the conductive matrix. We further determine that polysulfide loss can be minimized by increasing the current density (>C/10), thus reducing the sulfur formation period. Analysis of the kinetics determines that the conversion reactions are rate-limiting, specifically the formation of metallic iron at rates above C/8. While focused on FeS 2 , our findings on the influence of pressure, electrolyte interaction, and kinetics are broadly applicable to other conversion cathode systems.

Transition metal phosphorus trisulfide materials have received considerable research interest since the 1980-1990s as they exhibit promising energy conversion and storage properties. However, the mechanistic insights into Li-ion storage in these materials are poorly understood to date. Here, we explore the lithiation of NiPS 3 material by employing in situ pair-distribution function analysis, Monte Carlo molecular dynamics calculations, and a series of ex situ characterizations. Our findings elucidate complex ion insertion and storage dynamics around a layered polyanionic compound, which undergoes intercalation and conversion reactions in a sequential manner. This study of NiPS 3 material exemplifies the Li-ion storage mechanism in transition metal phosphorus sulfide materials and provides insights into the challenges associated with achieving reliable, high-energy phosphorus trisulfide systems.

Atomic layer deposition (ALD) was used to control the stoichiometry of thin lithium aluminosilicate films, thereby enabling crystallization into the ion-conducting β-eucryptite LiAlSiO 4 phase. The rapid thermal annealed ALD film developed a well-defined epitaxial relationship to the silicon substrate: β-LiAlSiO 4 (12̅10)||Si (100) and β-LiAlSiO 4 (101̅0)||Si (001). The extrapolated room temperature ionic conductivity was found to be 1.2 × 10 -7 S/cm in the [12̅10] direction. Because of the unique 1-D channel along the c axis of β-LiAlSiO 4 , the epitaxial thin film has the potential to facilitate ionic transport if oriented with the c axis normal to the electrode surface, making it a promising electrolyte material for three-dimensional lithium-ion microbatteries.

Ionogels, pseudo-solid-state electrolytes consisting of an ionic liquid electrolyte confined in a mesoporous inorganic matrix, have attracted interest recently due to their high ionic conductivity and physicochemical stability. These traits, coupled with their inherent solution processability, make them a viable solid electrolyte for solid-state battery systems. Despite the promising properties of ionogels, there have been very few investigations of the electrode-ionogel interface. In the present study, X-ray photoelectron spectroscopy, Raman spectroscopy, and electrochemical measurements were utilized to probe the surface reactions occurring at the electrode-ionogel interface for several electrode materials. Our results indicate that the sol acidity initiates breakdown of the organic constituents of the sol and reduction of the transition metals present in the electrode materials. This chemical attack forms an organic surface layer and affects the electrode composition, both of which can impede Li + access. By modifying the silica sol-gel reaction via a two-step acid-base catalysis, these interfacial reactions can be avoided. Results are shown for a LiCoO 2 electrode in which a high Li-ion capacity and stable cycling were achieved.

Ongoing technological advances in diverse fields including portable electronics, transportation, and green energy are often hindered by the insufficient capability of energy-storage devices. By taking advantage of two different electrode materials, asymmetric supercapacitors can extend their operating voltage window beyond the thermodynamic decomposition voltage of electrolytes while enabling a solution to the energy storage limitations of symmetric supercapacitors. This review provides comprehensive knowledge to this field. We first look at the essential energy-storage mechanisms and performance evaluation criteria for asymmetric supercapacitors to understand the wide-ranging research conducted in this area. Then we move to the recent progress made for the design and fabrication of electrode materials and the overall structure of asymmetric supercapacitors in different categories. We also highlight several key scientific challenges and present our perspectives on enhancing the electrochemical performance of future asymmetric supercapacitors.

The Lewis acid-base adduct approach has been widely used to form uniform perovskite films, which has provided a methodological base for the development of high-performance perovskite solar cells. However, its incompatibility with formamidinium (FA)-based perovskites has impeded further enhancement of photovoltaic performance and stability. Here, we report an efficient and reproducible method to fabricate highly uniform FAPbI 3 films via the adduct approach. Replacement of the typical Lewis base dimethyl sulfoxide (DMSO) with N-methyl-2-pyrrolidone (NMP) enabled the formation of a stable intermediate adduct phase, which can be converted into a uniform and pinhole-free FAPbI 3 film. Infrared and computational analyses revealed a stronger interaction between NMP with the FA cation than DMSO, which facilitates the formation of a stable FAI·PbI 2 ·NMP adduct. On the basis of the molecular interactions with different Lewis bases, we proposed criteria for selecting the Lewis bases. Owed to the high film quality, perovskite solar cells with the highest PCE over 20% (stabilized PCE of 19.34%) and average PCE of 18.83 ± 0.73% were demonstrated.

Composite structures for electrochemical energy storage are prepared on the basis of using the high-rate lithium ion insertion properties of Nb 2 O 5 . The Nb 2 O 5 is anchored on reduced graphene oxide (rGO) by hydrothermal synthesis to improve the charge-transfer properties, and by controlling the surface charge, the resulting Nb 2 O 5 -rGO particles are attached to a high-surface-area carbide-derived carbon scaffold without blocking its exfoliated layers. The electrochemical results are analyzed using a recently published multiscale physics model that provides significant insights regarding charge storage kinetics. In particular, the composite electrode exhibits surface-confined charge storage at potentials of <1.7 V (vs Li/Li + ), where faradaic processes dominate, and electrical double layer charge storage at potentials of >2.2 V. A hybrid device composed of the composite electrode with activated carbon as the positive electrode demonstrates increased energy density at power densities comparable to an activated carbon device, provided the hybrid device operates in the faradaic potential range.

Research on lithium (Li) metal chemistry has been rapidly gaining momentum nowadays not only because of the appealing high theoretical capacity, but also its indispensable role in the next-generation Li-S and Li-air batteries. However, two root problems of Li metal, namely high reactivity and infinite relative volume change during cycling, bring about numerous other challenges that impede its practical applications. In the past, extensive studies have targeted these two root causes by either improving interfacial stability or constructing a stable host. However, efficient surface passivation on three-dimensional (3D) Li is still absent. Here, we develop a conformal LiF coating technique on Li surface with commercial Freon R134a as the reagent. In contrast to solid/liquid reagents, gaseous Freon exhibits not only nontoxicity and well-controlled reactivity, but also much better permeability that enables a uniform LiF coating even on 3D Li. By applying a LiF coating onto 3D layered Li-reduced graphene oxide (Li-rGO) electrodes, highly reduced side reactions and enhanced cycling stability without overpotential augment for over 200 cycles were proven in symmetric cells. Furthermore, Li-S cells with LiF protected Li-rGO exhibit significantly improved cyclability and Coulombic efficiency, while excellent rate capability (∼800 mAh g -1 at 2 C) can still be retained.

Next generation Li-ion batteries will require negative electrode materials with energy densities many-fold higher than that found in the graphitic carbon currently used in commercial Li-ion batteries. While various nanostructured alloying-type anode materials may satisfy that requirement, such materials do not always exhibit long cycle lifetimes and/or their processing routes are not always suitable for large-scale synthesis. Here, we report on a high-performance anode material for next generation Li-ion batteries made of nanoporous Sn powders with hierarchical ligament morphology. This material system combines both long cycle lifetimes (more than 72% capacity retention after 350 cycles), high capacity (693 mAh/g, nearly twice that of commercial graphitic carbon), good charging/discharging capabilities (545 mAh/g at 1 A/g, 1.5C), and a scalable processing route that involves selective alloy corrosion. The good cycling performance of this system is attributed to its nanoporous architecture and its unique hierarchical ligament morphology, which accommodates the large volume changes taking place during lithiation, as confirmed by synchrotron-based ex-situ X-ray 3D tomography analysis. Our findings are an important step for the development of high-performance Li-ion batteries.

Demonstration of three-dimensional all-solid-state Li-ion batteries (3D SSLIBs) has been a long-standing goal for numerous researchers in the battery community interested in developing high power and high areal energy density storage solutions for a variety of applications. Ideally, the 3D geometry maximizes the volume of active material per unit area, while keeping its thickness small to allow for fast Li diffusion. In this paper, we describe experimental testing and simulation of 3D SSLIBs fabricated using materials and thin-film deposition methods compatible with semiconductor device processing. These 3D SSLIBs consist of Si microcolumns onto which the battery layers are sequentially deposited using physical vapor deposition. The power performance of the 3D SSLIBs lags significantly behind that of similarly prepared planar SSLIBs. Analysis of the experimental results using finite element modeling indicates that the origin of the poor power performance is the structural inhomogeneity of the 3D SSLIB, coupled with low electrolyte ionic conductivity and diffusion rate in the cathode, which lead to highly nonuniform internal current density distribution and poor cathode utilization.

Charge storage devices with high energy density and enhanced rate capabilities are highly sought after in today's mobile world. Although several high-rate pseudocapacitive anode materials have been reported, cathode materials operating in a high potential range versus lithium metal are much less common. Here, we present a nanostructured version of the well-known cathode material, LiMn2O4. The reduction in lithium-ion diffusion lengths and improvement in rate capabilities is realized through a combination of nanocrystallinity and the formation of a 3-D porous framework. Materials were fabricated from nanoporous Mn3O4 films made by block copolymer templating of preformed nanocrystals. The nanoporous Mn3O4 was then converted via solid-state reaction with LiOH to nanoporous LixMn2O4 (1 < x < 2). The resulting films had a wall thickness of ∼15 nm, which is small enough to be impacted by inactive surface sites. As a consequence, capacity was reduced by about half compared to bulk LiMn2O4, but both charge and discharge kinetics as well as cycling stability were improved significantly. Kinetic analysis of the redox reactions was used to verify the pseudocapacitive mechanisms of charge storage and establish the feasibility of using nanoporous LixMn2O4 as a cathode in lithium-ion devices based on pseudocapacitive charge storage.

Glucose oxidase-based biofuel cells are a promising source of alternative energy for small device applications, but still face the challenge of achieving robust electrical contact between the redox enzymes and the current collector. This paper reports on the design of an electrode consisting of glucose oxidase covalently attached to gold nanoparticles that are assembled onto a genetically engineered M13 bacteriophage using EDC-NHS chemistry. The engineered phage is modified at the pIII protein to attach onto a gold substrate and serves as a high-surface-area template. The resulting "nanomesh" architecture exhibits direct electron transfer (DET) and achieves a higher peak current per unit area of 1.2 mA/cm(2) compared to most other DET attachment schemes. The final enzyme surface coverage on the electrode was calculated to be approximately 4.74 × 10(-8) mol/cm(2), which is a significant improvement over most current glucose oxidase (GOx) DET attachment methods.

Single-layer and few-layer transition metal dichalcogenides have been extensively studied for their electronic properties, but their energy-storage potential has not been well explored. This paper describes the structural and electrochemical properties of few-layer TiS2 nanocrystals. The two-dimensional morphology leads to very different behavior, compared to corresponding bulk materials. Only small structural changes occur during lithiation/delithiation and charge storage characteristics are consistent with intercalation pseudocapacitance, leading to materials that exhibit both high energy and power density.

This Letter examines the physical and chemical changes that occur at the interface of methyl-terminated alkanethiol self-assembled monolayers (SAMs) after exposure to cell culture media used to derive embryoid bodies (EBs) from pluripotent stem cells. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy analysis of the SAMs indicates that protein components within the EB cell culture medium preferentially adsorb at the hydrophobic interface. In addition, we examined the adsorption process using surface plasmon resonance and atomic force microscopy. These studies identify the formation of a porous, mat-like adsorbed protein film with an approximate thickness of 2.5 nm. Captive bubble contact angle analysis reveals a shift toward superhydrophilic wetting behavior at the cell culture interface due to adsorption of these proteins. These results show how EBs are able to remain in suspension when derived on hydrophobic materials, which carries implications for the rational design of suspension culture interfaces for lineage specific stem-cell differentiation.

We have devised a moderate temperature hot-pressing route for preparing metal-matrix composites which possess tunable thermal expansion coefficients in combination with high electrical and thermal conductivities. The composites are based on incorporating ZrW2O8, a material with a negative coefficient of thermal expansion (CTE), within a continuous copper matrix. The ZrW2O8 enables us to tune the CTE in a predictable manner, while the copper phase is responsible for the electrical and thermal conductivity properties. An important consideration in the processing of these materials is to avoid the decomposition of the ZrW2O8 phase. This is accomplished by using relatively mild hot-pressing conditions of 500 °C for 1 h at 40 MPa. To ensure that these conditions enable sintering of the copper, we developed a synthesis route for the preparation of Cu nanoparticles (NPs) based on the reduction of a common copper salt in aqueous solution in the presence of a size control agent. Upon hot pressing these nanoparticles at 500 °C, we are able to achieve 92-93% of the theoretical density of copper. The resulting materials exhibit a CTE which can be tuned between the value of pure copper (16.5 ppm/°C) and less than 1 ppm/°C. Thus, by adjusting the relative amount of the two components, the properties of the composite can be designed so that a material with high electrical conductivity and a CTE that matches the relatively low CTE values of semiconductor or thermoelectric materials can be achieved. This unique combination of electrical and thermal properties enables these Cu-based metal-matrix composites to be used as electrical contacts to a variety of semiconductor and thermoelectric devices which offer stable operation under thermal cycling conditions.

Growing global energy demands coupled with environmental concerns have increased the need for renewable energy sources. For intermittent renewable sources like solar and wind to become available on demand will require the use of energy storage devices. Batteries and supercapacitors, also known as electrochemical capacitors (ECs), represent the most widely used energy storage devices. Supercapacitors are frequently overlooked as an energy storage technology, however, despite the fact that these devices provide greater power, much faster response times, and longer cycle life than batteries. Their limitation is that the energy density of ECs is significantly lower than that of batteries, and this has limited their potential applications. This Account reviews our recent work on improving pseudocapacitive energy storage performance by tailoring the electrode architecture. We report our studies of mesoporous transition metal oxide architectures that store charge through surface or near-surface redox reactions, a phenomenon termed pseudocapacitance. The faradaic nature of pseudocapacitance leads to significant increases in energy density and thus represents an exciting future direction for ECs. We show that both the choice of material and electrode architecture is important for producing the ideal pseudocapacitor device. Here we first briefly review the current state of electrode architectures for pseudocapacitors, from slurry electrodes to carbon/metal oxide composites. We then describe the synthesis of mesoporous films made with amphiphilic diblock copolymer templating agents, specifically those optimized for pseudocapacitive charge storage. These include films synthesized from nanoparticle building blocks and films made from traditional battery materials. In the case of more traditional battery materials, we focus on using flexible architectures to minimize the strain associated with lithium intercalation, that is, the accumulation of lithium ions or atoms between the layers of cathode or anode materials that occurs as batteries charge and discharge. Electrochemical analysis of these mesoporous films allows for a detailed understanding of the origin of charge storage by separating capacitive contributions from traditional diffusion-controlled intercalation processes. We also discuss methods to separate the two contributions to capacitance: double-layer capacitance and pseudocapacitance. Understanding these contributions should allow the selection of materials with an optimized architecture that maximize the contribution from pseudocapacitance. From our studies, we show that nanocrystal-based nanoporous materials offer an architecture optimized for high levels of redox or surface pseudocapacitance. Interestingly, in some cases, materials engineered to minimize the strain associated with lithium insertion can also show intercalation pseudocapacitance, which is a process where insertion processes become so kinetically facile that they appear capacitive. Finally, we conclude with a summary of simple design rules that should result in high-power, high-energy-density electrode architectures. These design rules include assembling small, nanosized building blocks to maximize electrode surface area; maintaining an interconnected, open mesoporosity to facilitate solvent diffusion; seeking flexibility in electrode structure to facilitate volume expansion during lithium insertion; optimizing crystalline domain size and orientation; and creating effective electron transport pathways.

Block copolymer templating of inorganic materials is a robust method for the production of nanoporous materials. The method is limited, however, by the fact that the molecular inorganic precursors commonly used generally form amorphous porous materials that often cannot be crystallized with retention of porosity. To overcome this issue, here we present a general method for the production of templated mesoporous materials from preformed nanocrystal building blocks. The work takes advantage of recent synthetic advances that allow organic ligands to be stripped off of the surface of nanocrystals to produce soluble, charge-stabilized colloids. Nanocrystals then undergo evaporation-induced co-assembly with amphiphilic diblock copolymers to form a nanostructured inorganic/organic composite. Thermal degradation of the polymer template results in nanocrystal-based mesoporous materials. Here, we show that this method can be applied to nanocrystals with a broad range of compositions and sizes, and that assembly of nanocrystals can be carried out using a broad family of polymer templates. The resultant materials show disordered but homogeneous mesoporosity that can be tuned through the choice of template. The materials also show significant microporosity, formed by the agglomerated nanocrystals, and this porosity can be tuned by the nanocrystal size. We demonstrate through careful selection of the synthetic components that specifically designed nanostructured materials can be constructed. Because of the combination of open and interconnected porosity, high surface area, and compositional tunability, these materials are likely to find uses in a broad range of applications. For example, enhanced charge storage kinetics in nanoporous Mn(3)O(4) is demonstrated here.

An ideal technique for observing nanoscale assembly would provide atomic-resolution images of both the products and the reactants in real time. Using a transmission electron microscope we image in situ the electrochemical deposition of lead from an aqueous solution of lead(II) nitrate. Both the lead deposits and the local Pb(2+) concentration can be visualized. Depending on the rate of potential change and the potential history, lead deposits on the cathode in a structurally compact layer or in dendrites. In both cases the deposits can be removed and the process repeated. Asperities that persist through many plating and stripping cycles consistently nucleate larger dendrites. Quantitative digital image analysis reveals excellent correlation between changes in the Pb(2+) concentration, the rate of lead deposition, and the current passed by the electrochemical cell. Real-time electron microscopy of dendritic growth dynamics and the associated local ionic concentrations can provide new insight into the functional electrochemistry of batteries and related energy storage technologies.

Electrical energy storage plays an increasingly important role in modern society. Current energy storage methods are highly dependent on lithium-ion energy storage devices, and the expanded use of these technologies is likely to affect existing lithium reserves. The abundance of sodium makes Na-ion-based devices very attractive as an alternative, sustainable energy storage system. However, electrodes based on transition-metal oxides often show slow kinetics and poor cycling stability, limiting their use as Na-ion-based energy storage devices. The present paper details a new direction for electrode architectures for Na-ion storage. Using a simple hydrothermal process, we synthesized interpenetrating porous networks consisting of layer-structured V(2)O(5) nanowires and carbon nanotubes (CNTs). This type of architecture provides facile sodium insertion/extraction and fast electron transfer, enabling the fabrication of high-performance Na-ion pseudocapacitors with an organic electrolyte. Hybrid asymmetric capacitors incorporating the V(2)O(5)/CNT nanowire composites as the anode operated at a maximum voltage of 2.8 V and delivered a maximum energy of ∼40 Wh kg(-1), which is comparable to Li-ion-based asymmetric capacitors. The availability of capacitive storage based on Na-ion systems is an attractive, cost-effective alternative to Li-ion systems.

Amphiphilic block copolymers are very attractive as templates to produce inorganic architectures with nanoscale periodicity because of their ability to form soft superstructures and to interact with inorganic materials. In this paper, we report the synthesis and electrochemical properties of highly ordered mesoporous T-Nb(2)O(5), L-Ta(2)O(5), and TaNbO(5) solid solution thin films with iso-oriented layered nanocrystalline domains. These oxide materials were fabricated by coassembly of inorganic sol-gel reagents with a poly(ethylene-co-butylene)-b-poly(ethylene oxide) diblock copolymer, referred to as KLE. We establish that all materials employed here are highly crystalline and have an ordered cubic pore-solid architecture after thermal treatment. We also demonstrate that these group V transition metal oxides can be readily produced with a high degree of crystallographic alignment on virtually any substrate in contrast to classical solution-phase epitaxy which requires the use of a single-crystalline substrate to achieve oriented crystal growth. Moreover, we show the benefits of producing a material with both a mesoporous morphology and crystallographically oriented domains. Mesoporous T-Nb(2)O(5) films exhibit high levels of pseudocapacitive charge storage and much higher capacities than mesoporous amorphous films of the same initial Nb(2)O(5) composition. Part of this high capacity stems from very facile intercalation pseudocapacitance. This process occurs at rates comparable to traditional redox pseudocapacitance in high surface area Nb(2)O(5) because of the periodic nanoscale porosity, the iso-orientation of the layered nanocrystalline pore walls, and the mechanical flexibility of periodic porous materials.

In this work, we report the synthesis and characterization of highly ordered mesoporous CeO(2) thin films with crystalline walls. While this article focuses on electrochemical studies of CeO(2) with periodic nanoscale porosity, we also examine the mechanical properties of these films and show how pore flexing can be used to facilitate intercalation of lithium ions. Mesoporous samples were prepared by dip-coating using the large diblock copolymer KLE as the organic template. We establish that the films have a mesoporous network with a biaxially distorted cubic pore structure and are highly crystalline at the atomic scale when heated to temperatures above 500 degrees C. Following a previously reported approach, we were able to use the voltammetric sweep rate dependence to determine quantitatively the capacitive contribution to electrochemical charge storage. The net result is that mesoporous CeO(2) films exhibit reasonable levels of pseudocapacitive charge storage and much higher capacities than samples prepared without any polymer template. Part of this increased capacity stems from the fact that these films are able to expand normal to the substrate upon intercalation of lithium ions by flexing of the nanoscale pores. This flexing relieves stress from volume expansion that normally inhibits charge storage. Overall, the results described in this work provide fundamental insight into how nanoscale structure and mechanical flexibility can be used to increase charge storage capacity in metal oxides.

A large electrochemical isotopic effect is observed upon the electrodeposition of lithium from solutions of propylene carbonate producing isotopically light metal deposits. The magnitude of fractionation is controlled by the applied overpotential and is largest close to equilibrium. Calculated partition function ratios for tetrahedrally coordinated lithium complexes and metallic lithium predict an equilibrium fractionation close to that measured experimentally.

The advantages in using nanoscale materials for electrochemical energy storage are generally attributed to short diffusion path lengths for both electronic and lithium ion transport. Here, we consider another contribution, namely the charge storage from faradaic processes occurring at the surface, referred to as pseudocapacitive effect. This paper describes the synthesis and pseudocapacitive characteristics of block copolymer templated anatase TiO(2) thin films synthesized using either sol-gel reagents or preformed nanocrystals as building blocks. Both materials are highly crystalline and have large surface areas; however, the structure of the porosity is not identical. The different titania systems are characterized by a combination of small- and wide-angle X-ray diffraction/scattering, combined with SEM imaging and physisorption measurements. Following our previously reported approach, we are able to use the voltammetric sweep rate dependence to determine quantitatively the capacitive contribution to the current response. Considerable enhancement of the electrochemical properties results when the films are both made from nanocrystals and mesoporous. Such materials show high levels of capacitive charge storage and high insertion capacities. By contrast, when mesoscale porosity is created in a material with dense walls (rather than porous walls derived from the aggregation of nanocrystals), insertion capacities comparable to templated nanocrystal films can be achieved, but the capacitance is much lower. The results presented here illustrate the importance of pseudocapacitive behavior that develops in high surface area mesoporous oxide films. Such systems provide a new class of pseudocapacitive materials, which offer increased charge storage without compromising charge storage kinetics.

We report an effective method to fabricate two-dimensional (2D) periodic oxide nanopatterns using S-layer proteins as a template. Specifically, S-layer proteins with a unit cell dimension of 20 nm were reassembled on silicon substrate to form 2D arrays with ordered pores of nearly identical sizes (9 nm). Octadecyltrichlorosilane (ODTS) was utilized to selectively react with the S-layer proteins, but not the Si surface exposed through the pores defined by the proteins. Because of the different surface functional groups on the ODTS-modified S-layer proteins and Si surface, area-selective atomic layer deposition of metal oxide-based high-k materials, such as hafnium oxide, in the pores was achieved. The periodic metal oxide nanopatterns were generated on Si substrate after selective removal of the ODTS-modified S-layer proteins. These nanopatterns of high-k materials are expected to facilitate further downscaling of logic and memory nanoelectronic devices.

In this paper, we present a new approach for protecting metallic lithium surfaces based on a reaction between the thin native layer of lithium hydroxide present on the surface and various chlorosilane derivatives. The chemical composition of the resulting layer and the chemistry involved in layer formation were analyzed by polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDX). Spectroscopy shows the disappearance of surface hydroxide groups and the appearance of silicon and chloride on the lithium surface. Differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS) show that this surface treatment protects the lithium from certain gas-phase reactions and is ionically conductive.

Research on the properties and applications of molecules doped into sol-gel-derived silica matrices has expanded rapidly. This Account begins with a brief review of the use of the dopant molecules as probes of the changes that occur as the system evolves from the initial sol to the final xerogel during the formation of monoliths, thin films, and mesostructured films. Methods of deliberately placing desired molecules in specific regions of the mesostructure are discussed, and an application, energy transfer, is presented. Finally, encapsulation of biological molecules is examined, and two important aspects, stabilization of the biomolecules and applications as biosensors, are described.

Plasmepsin IV (Plm IV) is one of the aspartic proteases present in the food vacuole of the malaria parasite Plasmodium falciparum involved in host hemoglobin degradation by the parasite. Using a series of previously synthesized plasmepsin inhibitors [Ersmark, K., et al. (2005) J. Med. Chem. 48, 6090-106], we report here experimental data and theoretical analysis of their inhibitory activity toward Plm IV. All compounds share a 1,2-dihydroxyethylene unit as the transition state mimic. They possess symmetric P1 and P1' side chains and either a diacylhydrazine, a five-membered oxadiazole ring, or a retroamide at the P2 and P2' positions. Experimental binding affinities are compared to those predicted by the linear interaction energy (LIE) method and an empirical scoring function, using both a crystal structure and a homology model for the enzyme. Molecular dynamics (MD) simulations of the modeled complexes allow a rational interpretation of the structural determinants for inhibitor binding. A ligand bearing a P2 and P2' symmetric oxadiazole which is devoid of amide bonds is identified both experimentally and theoretically as the most potent inhibitor of Plm IV. For the P2 and P2' asymmetric compounds, the results are consistent with earlier predictions regarding the mode of binding of this class of inhibitors to Plm II. Theoretical estimation of selectivity for some compounds is also reported. Significant features of the Plm IV binding pocket are discussed in comparison to related enzymes, and the results obtained here should be helpful for further optimization of inhibitors.

Methods of making mesostructured sol-gel silicate thin films containing two different molecules deliberately placed in two different spatially separated regions in a one-step, one-pot preparation are developed and demonstrated. When the structure-directing agent is the surfactant cetyltrimethylammonium bromide, the structure is 2-D hexagonal with lattice spacings between 31.6 and 42.1 angstroms depending on the dopant molecules and their concentrations. The three general strategies that are used to place the molecules are philicity (like dissolves like), bonding, and bifunctionality. These strategies take advantage of the different chemical and physical properties of the regions of the films. These regions are the inorganic silicate framework, the hydrophobic organic interior of the micelles, and the ionic interface between them. Luminescent molecules that possess the physical and chemical properties appropriate for the desired strategies are chosen. Lanthanide and ruthenium complexes with condensable trialkoxysilane groups are incorporated into the silicate framework. 1,4-Naphthoquinone, pyrene, rhodamine 6G and coumarin 540A, and lanthanides with no condensable trialkoxysilanes occupy the hydrophobic core of micelles by virtue of their hydrophobicity. The locations of the molecules are determined by luminescence spectroscopy and by luminescence lifetime measurements. In all cases, the long-range order templated into the thin film is verified by X-ray diffraction. The simultaneous placement of two molecules in the structured film and the maintenance of long-range order require a delicate balance among film preparation methodology, design of the molecules to be incorporated in specific regions, and concentrations of all of the species.

The antigenic determinants of nonhistone high mobility group chromosomal proteins 1 (HMG-1) and 2 (HMG-2) were studied with rabbit antisera elicited against HMG-1 and against HMG-2 and monoclonal antibodies elicited by HMG-1. The monoclonal antibodies did not distinguish between the two proteins, suggesting that they have specificity toward a shared determinant. Whereas anti-HMG-1 did not, anti-HMG-2 did distinguish between the proteins, suggesting that the anti-HMG-2 serum contains antibodies against peptides which differ between the proteins. Peptides were generated from HMG-1 and HMG-2 by controlled digestion with trypsin and pepsin. Analysis of the digests by ELISA and by sodium dodecyl sulfate electrophoresis followed by diazobenzyloxymethyl transfer, antibody binding and autoradiography revealed that most of the antibodies are against sequential determinants some of which are smaller than 3000 in molecular weight.