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This review provides a brief background on the extraction of uranium from seawater as well as recent work by the United States Department of Energy on this project. The world's oceans contain uranium at 3 parts per billion, and despite this low concentration, there has been historical interest in harvesting it, mainly in Japan in the 1980s and the United States in this decade. Improvements in materials, chemistry, and deployment methods have all been made, with the ultimate goal of lower cost. This has been partially realized, dropping from approximately $2000 per kg U3O8 extracted in 1984 to $500 per kg today, although this is not yet competitive with terrestrial uranium. This technology may become cost-competitive if the cost of land-based uranium rises, especially if seawater extraction technology is improved further. The coordination chemistry aspects of the project are described in more detail, exploring the functional groups that are present on typical polymer sorbents as well as small-molecule analogues of these ligands. Selectivity for uranium over other metals, particularly vanadium, remains problematic, and techniques to both quantify binding strength and selectivity in order to overcome this issue are essential for future cost improvements. [ABSTRACT FROM AUTHOR]

We report on a straightforward strategy to fabricate bioactive glycosylated gold nanoparticles via a combination of RAFT polymerization, carbohydrate ligation through reductive amination and thiol–gold self-assembly. This approach is used for the design of gold nanoparticles decorated with the complex sialylated glycan Neu5Ac-α-2-6-Gal, and we demonstrate multivalent and specific recognition between the nanoparticles, lectins and hemagglutinin on the surface of the influenza virus. [ABSTRACT FROM AUTHOR]

Recently, cobalt oxides/hydroxides have attracted increasing attention in the electrocatalytic oxidation reaction of 5-hydroxymethylfurfural (HMFOR) under ambient conditions for 2,5-furandicarboxylic acid (FDCA) production, but understanding of the interplay of defective sites (i.e., oxygen vacancies and porosity) remains lacking. Herein, a series of defective cobalt oxide hydrate (CoOxHy) nanosheets were fabricated via room-temperature reductive treatments with methylamine (MA) and/or NaBH4 (BH). These defective CoOxHy nanosheets possessed abundant oxygen vacancies in relation to high Co2+/Co3+ ratios and high porosity, with a largely maintained ultrathin lamellar framework, and thus exhibited markedly improved catalytic activity and selectivity for HMFOR. DFT calculations also verified the beneficial role of oxygen vacancies towards HMF adsorption and activation, preferentially via the aldehyde group of HMF. In the optimal CoOxHy-MA, 98% FDCA yield and a faradaic efficiency of 83% were achieved within 200 min at a constant potential of 1.52 V vs. RHE. The mesoporosity mainly induced by MA improved the mass transportation of reactants and products, leading to a higher rate of HMFOR. Meanwhile, with the additional in-sheet micropores mainly induced by BH, the selectivity towards the oxidation intermediate 5-formyl-2-furancarboxylic acid (FFCA) significantly increased, probably due to the accelerated penetration of FFCA instead of further oxidation to FDCA. This work highlights the simultaneous regulation of the oxygen vacancies and porosity of metal oxide/hydroxide catalysts by facile reductive treatments for efficient electrochemical biomass conversion. [ABSTRACT FROM AUTHOR]

Hydrolysis of Th(iv) was studied in tetraethylammonium perchlorate (0.10 mol kg−1) at variable temperatures (283–358 K) by potentiometry and microcalorimetry. Three hydrolysis reactions, mTh4+ + nH2O = Thm(OH)n(4m−n)+ + nH+, in which (n,m) = (2,2), (8,4), and (15,6), were invoked to describe the potentiometric and calorimetric data for solutions with the [hydroxide]/[Th(iv)] ratio ≤ 2. At higher ratios, the formation of (16,5) cannot be excluded. The hydrolysis constants, *β2,2, *β8,4, and *β15,6, increased by 3, 7, and 11 orders of magnitude, respectively, as the temperature was increased from 283 to 358 K. The enhancement is mainly due to the significant increase of the degree of ionization of water as the temperature rises. All three hydrolysis reactions are endothermic at 298 K, with enthalpies of (118 ± 4) kJ mol−1, (236 ± 7) kJ mol−1, and (554 ± 4) kJ mol−1 for ΔH2,2, ΔH8,4, and ΔH15,6 respectively. The hydrolysis constants at infinite dilution have been obtained with the specific ion interaction approach. The applicability of three approaches for estimating the equilibrium constants at different temperatures, including the constant enthalpy approach, the constant heat capacity approach and the DQUANT equation was evaluated with the data from this work. [ABSTRACT FROM AUTHOR]

We report a facile strategy for synthesizing uniform heterometallic bi/tri-atom clusters starting from mono-metallic atoms in the liquid phase. Specifically, Pt1,2Cu bi/tri-atoms are prepared by reducing CuCl2 at preformed Pt1 atoms with ethanol inside a PDMS-PEG protective layer. The metal atoms in the Pt1,2Cu clusters are in reduced chemical states. [ABSTRACT FROM AUTHOR]

A novel organic--inorganic hybrid monocapped/bicapped Keggin structure [CoII(bpy)3]6(H2bpy)[(CoIIbpy)2(PMo8VIMo4O40)]3 [(CoIIbpy)-(PMo8VIMo4V O40)]·16H2O (bpy = 2,2'-bipyridine) was synthesized and shown to be an efficient visible light-driven catalyst for water oxidation. [ABSTRACT FROM AUTHOR]

The solid electrolyte interphase (SEI) layer on a silicon anode is investigated by SERS. Gold electrodeposition on a silicon electrode is confirmed by SEM, and Raman enhancement is proved, allowing determination of the partial composition of its SEI. For the first time, organophosphate-derivatives seem to be detected by Raman. [ABSTRACT FROM AUTHOR]

Selectively producing chemicals from cellulosic carbohydrate pyrolysis in large quantities is challenging, especially anhydro-monosaccharides with double-ring, triple-ring, and furan/pyran structures. Formation of these sugar derivatives greatly improves when the pyranose ring opening is inhibited during pyrolysis, which is accomplished by chemically replacing the hydroxyl group at the anomeric carbon with an alkoxy group. A simpler ring-locking approach is required for scalable chemical production, however. In this work, we demonstrate that introducing Na2SO4 and H2SO4 to glucose pyrolysis significantly increases levoglucosan (LGA) formation, from a 6% yield to as high as 40% at 350 °C. With H2SO4 as the acid catalyst, Na+ acts to inhibit the ring opening. Glucose pyrolysis with different alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) gives different reaction products, which can be explained largely by an ionic electronegativity effect. Weaker electronegativity promotes the formation of a ring-opened product such as 5-hydroxymethylfurfural (HMF), and stronger electronegativity increases the formation of sequential dehydration products like levoglucosenone (LGO). Sodium has the optimum ionic electronegativity for preferential association with the ring oxygen. The Na2SO4/H2SO4 combination improved LGA yields for all carbohydrate substrates tested (up to 70%), including lignocellulose. These findings highlight the potential of using alkali metal salts to produce anhydrosugars in high yields from cellulosic carbohydrate pyrolysis. [ABSTRACT FROM AUTHOR]

The use of amidoxime-functionalized polymer fibers as a sorbent for uranium has attracted recent interest for the extraction of uranium from seawater. Vanadium is one of the main competing ions for uranium sorption as V(v) species, however, vanadium is also present as V(iv) in seawater. In the present study, the interactions of V(iv) with amidoxime and similar ligands were explored. Attempts were made to synthesize V(iv) complexes of glutaroimide-dioxime, a molecular analogue of polymer sorbents. However, V(iv) was found to react irreversibly with glutaroimide-dioxime and other oxime groups, oxidizing to the V(v) oxidation state. We have explored the reactions and propose mechanisms, as well as characterized the redox behavior of the vanadium–glutaroimide-dioxime complex. [ABSTRACT FROM AUTHOR]

Producing bio-intermediates from lignocellulosic biomass with minimal process steps has a far-reaching impact on the biofuel industry. We studied the metal chloride catalyzed aldol condensation of furfural with acetone under conditions compatible with the upstream polysaccharide conversions to furfurals. In situ far infrared spectroscopy (FIR) was applied to guide the screening of aldol condensation catalysts based on the distinguishing characteristics of metal chlorides in their coordination chemistries with carbonyl-containing compounds. NiCl2, CoCl2, CrCl3, VCl3, FeCl3, and CuCl2 were selected as the potential catalysts in this study. The FIR results further helped to rationalize the excellent catalytic performance of VCl3 in furfural condensation with acetone, with 94.7% yield of biofuel intermediates (C8, C13) in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) solvent. Remarkably, addition of ethanol facilitated the acetal pathway of the condensation reaction, which dramatically increased the desired product selectivity over the furfural pathway. Most significantly, we demonstrate for the first time that VCl3 catalyzed aldol condensation in acidic medium is fully compatible with upstream polysaccharide hydrolysis to monosaccharide and the subsequent monosaccharide isomerization and dehydration to furfurals. Our preliminary results showed that a 44% yield of biofuel intermediates (C8, C13) can be obtained in one-pot conversion of xylose catalyzed by paired metal chlorides, CrCl2 and VCl3. A number of prior works have shown that the biofuel intermediates derived from the one-pot reaction of this work can be readily hydrogenated to biofuels. [ABSTRACT FROM AUTHOR]

The selective production of platform chemicals from thermal conversion of biomass-derived carbohydrates is challenging. As precursors to natural products and drug molecules, anhydrosugars are difficult to synthesize from simple carbohydrates in large quantities without side products, due to various competing pathways during pyrolysis. Here we demonstrate that the nonselective chemistry of carbohydrate pyrolysis is substantially improved by alkoxy or phenoxy substitution at the anomeric carbon of glucose prior to thermal treatment. Through this ring-locking step, we found that the selectivity to 1,6-anhydro-β-d-glucopyranose (levoglucosan, LGA) increased from 2% to greater than 90% after fast pyrolysis of the resulting sugar at 600 °C. DFT analysis indicated that LGA formation becomes the dominant reaction pathway when the substituent group inhibits the pyranose ring from opening and fragmenting into non-anhydrosugar products. LGA forms selectively when the activation barrier for ring-opening is significantly increased over that for 1,6-elimination, with both barriers affected by the substituent type and anomeric position. These findings introduce the ring-locking concept to sugar pyrolysis chemistry and suggest a chemical-thermal treatment approach for upgrading simple and complex carbohydrates. [ABSTRACT FROM AUTHOR]

The diaza crown ether dicarboxylate ligand, 4,4′-((1,7-dioxa-4,10-diazacyclododecane-4,10-diyl)bis(methylene)dibenzoate), L, forms a monomeric coordination complex of Co(ii) ions, CoL(H2O)2·2H2O, 1, and a coordination polymer (MnL·H2O)n, 2, with Mn(ii) ions under hydrothermal conditions. The monomeric coordination complex (structure 1) is polar with mirror symmetry and crystallizes in the non-centrosymmetric space group Cm. The mirror plane bisects the complex at the six-coordinate Co(ii) ion, the two oxygen atoms of the crown moiety and the two oxygen atoms from coordinated water molecules. The coordinated water molecules take part in strong, linear hydrogen bonds with carboxylate oxygens provided by neighboring Co(ii)–crown complexes resulting in a three-dimensional (1 : 1)n polar network in which the topology of the underlying 8-coordinated net is sqc3. The structure of 2 crystallizes in the orthorhombic Fdd2 space group as an infinite, polar triply interpenetrating three-dimensional network. The eight-coordinate Mn(ii) ion coordinates two oxygen and two nitrogen atoms of the crown moiety, as well as single carboxylate O atom from each of two neighboring ligands. In both structures, the ligand assumes a flexed-wing bird shape, with the two benzoate sidearms of the crown moiety locked in a syn orientation. The metal ion elevated above the plane of the diaza-crown oxygen and nitrogen atoms. The diaza-crown moiety with its two benzoate sidearms has the peculiar property of forming an oriented crystal structure where the metal-crown vectors are oriented parallel to each other in the crystal. However, the structures are achiral, but the rigid crystal lattice prevents re-orientation of the structure through inversion. The coordination polymer (MnL·H2O)n, 2, is a 3-center uninodal net with ths (ThSi2) topology. Computational results using the density functional theory (DFT) calculations explain why the flexed-wing bird shape is the preferred and most stable ligand conformation for metal ion binding. Both structures demonstrate magnetic properties that are characteristics of the respective non-interacting isolated paramagnetic transition metal ions that are present. [ABSTRACT FROM AUTHOR]

A series of amine-sulfonate functionalized ionic liquids (ASF-ILs) were synthesized, characterized, and evaluated for the dissolution of model biopolymers (cellulose, xylan, kraft lignin and lignosulfonate). The ASF-ILs were prepared in high atomic efficiency. Most of the ASF-ILs dissolve kraft lignin and lignosulfonate efficiently at 373 K, with solubilities of 0.220–0.385 g for kraft lignin and of 0.150–0.290 g for lignosulfonate per gram of ASF-ILs. In contrast, xylan and cellulose are scarcely soluble (＜5 mg g−1) in the ASF-ILs. Based on the results of the model lignin dissolution, four most promising ASF-ILs were selected and applied for the pretreatment of eucalyptus bark. The lignin was selectively fractionated by the ASF-ILs (393 K for 10 h, lignin removal was more than 40%). The fractionated lignin and the eucalyptus bark residues were then characterized by infrared spectroscopy and thermogravimetric analysis. Importantly, we demonstrate that enzymatic hydrolysis of the polysaccharide components of the eucalyptus bark to sugars was substantially enhanced after the pretreatment, most pronouncedly with the ASF-IL[Et4N][Me2NC4SO3]. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks {[Ln4(pztc)3(H2O)11]·10(H2O)}n (Ln = Gd(1), Tb(2); pztc = pyrazine-2,3,5,6-tetracarboxylate) containing variable coordination spheres and with a complex and unusual three dimensional structure, were synthesized by the reaction of H4pztc with the respective Ln(iii) salt in water under hydrothermal conditions. The compounds were characterized by single crystal X-ray crystallography, elemental and thermal analysis, and FTIR spectroscopy. The asymmetric units in these compounds have four symmetry-independent Ln(iii) ions and these are octa- and nona-coordinate centers, with irregular coordination polyhedra from [Ln(pztc)2(H2O)6], [Ln(pztc)2(H2O)4], [Ln(pztc)3(H2O)3], [Ln(pztc)3(H2O)], and [Ln(pztc)4] cluster units. The fully deprotonated ligand, pztc, coordinates to the Ln3+ ions through seven or through ten of its atoms (i.e., the maximum coordination number for this ligand). The three-dimensional open framework contains irregular channels along the [001] crystallographic direction. The channels are approximately 12 Å wide at their largest dimension and contain strongly hydrogen bonded water molecules of crystallization which further stabilize the structure. The solvent accessible volume is 20% of the total volume. The structures exhibit magnetic behavior that is characteristic of the respective isolated paramagnetic lanthanide ions. [ABSTRACT FROM AUTHOR]

Increasing the glucose loading in the 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid containing a dissolved CrCl3 catalyst system led to excessive formation of humins and a serious decrease in the 5-hydroxymethylfurfural (5-HMF) yield. A biphasic system containing glycol dimethyl ether (GDE) as the extraction phase, and [BMIM]Cl/CrCl3/glucose in combination with a partitioned amount of GDE and an appropriate amount of water as the reaction phase was found to be highly efficient for the reaction; CrCl3 catalyzed the formation of 5-HMF in 64.5 mol% yield from a very high glucose concentration (80 wt% with respect to the ionic liquid) at 108 °C. This 5-HMF yield in the [BMIM]Cl–GDE–H2O ternary biphasic system nearly doubled that obtained in the single [BMIM]Cl/CrCl3/glucose reaction phase. Importantly, the GDE phase contained about 56% of the generated 5-HMF without detectable contamination by the ionic liquid or carbohydrates. GDE served multiple functions: as a hydrogen-bond acceptor, it exhibited excellent extraction performance for 5-HMF; due to its low boiling point and suitable solubility saturation point in the ionic liquid, a sustained GDE bubbling phenomenon in the ionic liquid phase was observed that promoted the rate of inter-phase mass-transfer of 5-HMF in reactions; and GDE mediated the [BMIM]Cl phase to a reduced viscosity. In addition, an appropriate amount of water in the ternary system promoted the extraction efficiency of 5-HMF and also lowered the viscosity of [BMIM]Cl/glucose. The ionic liquid–organics–water ternary biphasic system has been demonstrated for high 5-HMF productivity and separation efficiency. [ABSTRACT FROM AUTHOR]

B3LYP/DZP level calculations are used to predict B2O2 cage oligomers, which are constructed from polyhedra by locating their B–B bonds at edge midpoints and three oxygen atoms at each degree 3 vertex. The stability of such cage oligomers depends highly on the B2nOn (n = 3, 4, 5) cavities corresponding to the polyhedral faces. All such polyhedral oligomers are found to have larger cohesive energies (Ec's) than corresponding planar structures, except for the smallest (B2O2)6 tetrahedron with extremely high strain arising from the four B6O3 cavities forming the tetrahedron faces. Promising (B2O2)n cages with the highest cohesive energies include pentagonal dodecahedral (B2O2)30 (c-B30) with B10O5 cavities, truncated octahedral (B2O2)36 (t-B36-2) with B8O4 cavities, and truncated icosahedral (B2O2)90 (t-B90) with B10O5 cavities. However, smaller (B2O2)n oligomers are also expected to exhibit cage structures having B8O4 or even B6O3 cavities because of their large Ec(s). [ABSTRACT FROM AUTHOR]

A novel film electrode was assembled via a simple filtration process, with an rGO paper as the substrate and Ni–Mn LDH/graphene superlattice composites as the functional layer. The electrode presented typical pseudocapacitive behaviours with excellent rate property and cycle stability. [ABSTRACT FROM AUTHOR]

A novel organic–inorganic hybrid material with 2-D inorganic and 3-D organic connectivity has been assembled with one Cd–Ohydroxyl helix and two kinds of quadruple-stranded Cd–ligand helices, which also shows a highly-connected binodal (5,14-c) topological net. [ABSTRACT FROM AUTHOR]