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We report the high-capacity and selective uptake of Cr(VI) from water using the coordination polymer silver bipyridine acetate (SBA, [Ag(4,4'-bipy)][CH

Following the seminal theoretical work on the pleated β-sheet published by Pauling and Corey in 1951, the rippled β-sheet was hypothesized by the same authors in 1953. In the pleated β-sheet the interacting β-strands have the same chirality, whereas in the rippled β-sheet the interacting β-strands are mirror-images. Unlike with the pleated β-sheet that is now common textbook knowledge, the rippled β-sheet has been much slower to evolve. Much of the experimental work on rippled sheets came from groups that study aggregating racemic peptide systems over the course of the past decade. This includes MAX1/DMAX hydrogels (Schneider), L/D-KFE8 aggregating systems (Nilsson), and racemic Amyloid β mixtures (Raskatov). Whether a racemic peptide mixture is "ripple-genic" (

We report the crystal structures of four different neutral lanthanide (Ln = La, Nd, Eu and Gd) metal–organic frameworks based on the organic linker 2,6-naphthalenedicarboxylate (NDC). The materials are three-dimensional and crystallize in three distinct topologies, with distinct bonding modes of NDC and lanthanide coordination numbers ranging from seven to nine and varying geometry. We denote our materials SLUG-49 [La6(NDC)9(DMF)3·6 DMF], -50 [Nd2(NDC)3O(DMF)2], -51 [Eu2(NDC)3(DMF)2·DMF], and -52 [Gd4(NDC)6(DMF)4] (DMF = N,N-dimethylformamide). The structures exhibit similar thermal decomposition profiles and infrared spectra. The Eu(III)-based material exhibits a sharp red-orange luminescence at 613 nm with a quantum efficiency of 3.56%.

We report the structures of six anionic, isomorphous metal–organic frameworks [Ln(bpdc)2–][NH2(CH3)2+], where Ln = La, Ce, Nd, Eu, Gd, Er, and bpdc2– = biphenyl-4,4′-dicarboxylate = –O2C(C6H4)2CO2–...

We report the first example of linker modification for an N-donor Ag-based cationic material while maintaining and in some cases increasing the anion exchange capacity. Cationic silver(I) pyrazine nitrate selectively traps harmful oxo-anions from water such as permanganate, perrhenate and a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange for potential water purification. The host-guest interaction between the cationic layers of π-stacked silver pyrazine polymers and the incoming/outgoing interlamellar anions allows for the exchange. The exchange capacity over 24 h reached 435 and 818 mg/g for permanganate and perrhenate, respectively, a record for a crystalline metal-organic material and over five times the exchange capacity compared to commercial resin. The material also undergoes organic exchange as an analog for pharmaceutical waste, some of which have a carboxylate functionality at the neutral pH range typical of natural water sources. Both the as-synthesized and exchanged materials are characterized by a variety of analytical techniques.

We present the rapid synthesis of a series of metal–organic framework (MOF) thin films on indium tin oxide (ITO) glass. ITO was first electrodeposited with either copper or zinc microcrystalline fi...

Large Fe3O4@SiO2 nanoparticles (∼200 nm) functionalized with gold and poly(vinylpyrrolidone) have been synthesized, characterized, and evaluated for bioseparation and sensing applications. The particles have been characterized using a combination of experimental techniques including ultraviolet visible spectroscopy, energy-dispersive spectroscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, electron microscopy, superconducting quantum interference device magnetrometry, and surface-enhanced Raman sensing (SERS) spectroscopy. The particles have a unique surface morphology comprised of roughened gold nodules. The surface coatings prevent oxidation and render the particles easy to functionalize in order to target a wide range of moieties. The gold coverage is not only uniform across the entire particle surface but also ultrathin so as to maintain a high percentage of the cores magnetic saturation (∼68%) when compared to that of bare magnetite. The gold nodules facilitate the generation ...

We report the selective removal of perchlorate from water by a cationic coordination polymer in the highest observed capacity and rate to date. Silver bipyridine acetate [Ag(4,4′-bipy)+][CH3CO2–]·6H2O (bipy = bipyridine) is easily synthesized in water under ambient conditions (60 min with 99.1% yield). The material releases its environmentally benign acetate anions upon perchlorate uptake to 99.9% mol/mol completion in Millipore water. Actual contaminated industrial water from an underground plume (53 ppm initial perchlorate concentration) was treated to 96% mol/mol in 60 min. The uptake capacity is near-record high at 310 mg/g and is 94% complete within 30 min. Perchlorate exchange was also conducted at 1–30 ppm perchlorate typical of underground contaminated source sites, with up to 99.7% mol/mol completion.

We report the synthesis and antibacterial properties and mechanism of two Zn-based coordination polymers (CPs). The first, [Zn(bipy)(OH2)42+]1.5[ClO4−]3·(bipy)3(H2O), consists of a one-dimensional (1D) structure with two crystallographically independent octahedral zinc centers trans-coordinated by two 4,4′-bipy units and water groups. The second, [Zn1.5(CH3CO2)2(bipy)2+][ClO4−]·H2O, is a two-dimensional (2D) layered structure with the same polymers but bridged together into a layer by acetate and 4,4′-bipy. Both compounds exhibit sustained release of Zn2+ ions upon their gradual degradation in aqueous solution, which results in highly effective antibacterial activity towards Escherichia coli and particularly towards Staphylococcus epidermidis cells. This activity was evaluated in solution by broth dilution assays to determine minimal inhibition concentrations (MICs) as well as in the solid phase by agar diffusion tests to quantify the zones of inhibition (ZOI), and were in close agreement. Further, the biocidal mechanisms of the coordination polymers were investigated in vivo by fluorescence microscopy utilizing CellRox Green and propidium iodide as reactive oxygen species (ROS) and membrane disruption indicators, respectively. Both CPs show superior antibacterial activity compared to two standards, zinc acetate and zinc oxide, which is concluded to be due to both gradual and localized release of Zn2+ ions as well as electrostatic attraction to the bacterial cell surface afforded by their unique structures. This unique Zn release profile and interaction with bacterial surfaces affords marked antibacterial activity and suggests that manipulation of the Zn structures could lead to significant advancements in antimicrobial materials.

The desulfurization of JP-8 (Jet Propellant 8) fuel is of interest to the U.S. military because of its potential use as a fuel source for solid oxide fuel cells (SOFCs). SOFCs can be used to supply a steady stream of power during military silent watch missions. Adsorptive desulfurization is a promising alternative to hydrodesulfurization, which is unable to remove refractory sulfur compounds and achieve the ultra-low sulfur levels necessary to prevent poisoning of SOFCs. Adsorptive desulfurization could be a portable, on-site process performed on JP-8 stocks already in the field. Within the vast field of fuel processing/reformation, herein we focus on the current status of adsorptive desulfurization performed on JP-8 jet fuel. Currently, the best performing sorbents are those utilizing high surface area porous frameworks with pore sizes large enough to accommodate sulfur contaminants. Additionally, a variety of metals in ionic, metallic, and oxide form serve as promising active sites within these sorbents. Most reports focus on reformation technologies and sorbent materials for gas-phase desulfurization and hydrogen purification of low-sulfur content diesel or light fraction jet fuel. JP-8 is unique to the Army in terms of supply. This review will thus focus on ongoing efforts in the room temperature liquid desulfurization of JP-8 and its higher levels of impurities that are more complex and difficult to remove.

An in-depth study of the class of cationic materials [Ag(4,4'-bipy)+][X-] (where X- = CH3CO2-, NO3-, BF4-, ClO4-, and MnO4-) has led to key insights on the relationship between anion hydration energy, material structure, solubility, and stability. Since these materials show promise for their potential as water remediation tools, understanding their properties in detail is of significant importance. The structure of the starting and ending materials is the main driving force behind the resultant stability and solubility and can be successfully used to predict the ion exchange capabilities. The solubility trend was determined to be, from most soluble to least soluble, X- = CH3CO2- > NO3- ∼ BF4- > ClO4- > MnO4-. Kinetics and thermal stability also follow predictable trends but involve additional factors. For instance, the kinetics of NO3- to MnO4- exchange was much slower than expected based on that seen for NO3- to ClO4-. Powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the materials. Solubility was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. Ion exchange was analyzed with ion chromatography (IC) and ultraviolet-visible spectroscopy (UV-vis), and thermal stability was determined with thermogravimetric analysis (TGA).

An amorphous nickel and boron composite (NBC) was synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and sodium borohydride (NaBH4) in absolute ethanol, both in bulk and supported on mesoporous aluminosilicate nanoparticles (MASN). Comparatively, NBC-MASN demonstrated better catalytic activity for the selective reduction of the nitro group on a variety of polysubstituted nitroarenes, using hydrazine hydrate (N2H4·H2O) as the reducing agent at 25 °C. Reuse and regeneration of NBC-MASN for the reduction of p-nitrotoluene to p-toluidine were studied with NaBH4 acting as a regeneration agent. Good catalytic activity was sustained through nine reuse cycles when equimolar NaBH4 was present in situ with N2H4·H2O (99%-67% isolated aniline yield). The structure and composition of NBC and NBC-MASN were examined by electron microscopy, energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The results for NBC-MASN show that a thin (

We report a rare example of a sulfonate-based metal–organic framework (MOF) possessing a prototypical primitive-cubic topology, constructed with Jahn–Teller distorted Cu(II) centers and a mixed-linker (organosulfonate and N-donor) system. The inherent highly polar, permanent porosity contributes to the highest reported CO2 sorption properties to date among organosulfonate-based MOFs, outperforming the benchmark carboxylate MOF counterpart. Importantly, density functional theory calculations confirm that the CO2–sulfonate interaction plays an important role in CO2 capture. Indeed, the hydrothermal product demonstrates high robustness over a wide pH range as well as aqueous boiling conditions, overcoming the moisture sensitivity of conventional Cu2 paddlewheel-based MOFs. In addition, bulk synthesis of this material has been successfully achieved on a gram scale (>1 g) in a single batch with a high yield. Combining the high CO2 affinity and a robust nature, this sulfonate porous material is also an efficien...

We report a regenerable adsorbent for the removal of refractory organosulfur compounds from fossil fuels. The material is composed of well-dispersed silver nanoparticles confined within the mesochannels of aluminum-doped MCM-41 nanoparticles. With an average initial desulfurization capacity of 15 mg S·g–1, 79% desulfurization capacity is retained after six cycles for the removal of dibenzothiophene from n-decane. The addition of intraframework aluminum to form a mesoporous aluminosilicate nanoparticle (MASN) aids in the retention and dispersion of silver ions within the mesochannels (Ag-MASN). The nanoparticles are subsequently reduced by glow discharge plasma treatment in argon (PT-Ag-MASN). The size dispersion, surface area, and structural integrity were characterized by scanning electron microscopy, annular dark-field scanning transmission electron microscopy (ADF-STEM), nitrogen adsorption analysis (BET), and powder X-ray diffraction. Silver nanoparticle formation within the mesochannels of MASN was c...

The surprising discovery of salutary effects of low doses of carbon monoxide (CO) in mammalian physiology has raised intense research interest in CO delivery to biological targets under controlled conditions. In recent attempts, photoactive metal carbonyl complexes (photoCORMs) have been employed to trigger CO release at the target sites. In this work, a designed photoCORM namely, fac-[Re(CO)3(pbt) (PPh3)](CF3SO3) (1, pbt =2-(2-pyridyl)benzothiazole) has been synthesized and characterized by spectroscopic methods and crystallography. This photoCORM not only releases CO upon illumination with low-power UV light (305 nm, 5 mW cm–2) but also exhibits a “turn-off” of its orange luminescence (λem = 605 nm) upon release of one CO ligand. The latter property provides a convenient way to track the CO release event. The photoCORM 1 has been entrapped within the pores of the narrow channels of 100 nm mesoporous Al-MCM-41 nanoparticles and the loaded {Re-CO}@Al-MCM-41 MSNs have been characterized by powder X-ray dif...

M4Ag44(p-MBA)30 molecular nanoparticles, where M is an alkali metal, have recently been shown to have exceptional stability, which confers unique traits to this molecule. In particular, the synthesis is straightforward, produces a truly single-sized molecular product, and has a quantitative yield. Here we describe in detail the results of experimental and theoretical studies on the synthesis, structure, stability, and electronic and optical properties of M4Ag44(p-MBA)30, including ESI-MS, NMR, optical absorption, IR, TGA, and other measurements as well as DFT and TDDFT calculations. This work deepens our understanding of this important Ag molecule, which should facilitate its use in a wide range of fundamental studies and applications.

We report a detailed study of the host-guest interaction for a cationic metal-organic framework that can reversibly capture perchlorate. The structural transformation and flexibility of silver 4,4′-bipyridine nitrate (SBN) upon formation of silver 4,4′-bipyridine perchlorate (SBP) was evaluated by monitoring the anion exchange dynamics using a combination of powder X-ray diffraction (PXRD) with multinuclear 13C, 15N and 109Ag solid-state NMR spectra at different time intervals of the anion exchange. The structural transformation from SBN to SBP is complete within 70 minutes and was determined to take place by a solvent-mediated process. This pathway is confirmed by the morphological changes of the two crystalline materials observed by SEM. This key understanding may lead to application of this material towards perchlorate capture.

We present a new method in the synthesis of metal–organic framework (MOF) thin films using zinc oxide nanowires as the substrate. This facile method involves growing zinc oxide nanowires on a substrate (glass, transparent conducting oxide glass, Si wafer), followed by immersing the nanowire substrate in an iso-reticular metal–organic framework (IRMOF) precursor solution. The resulting 25 μm thick film is highly crystalline and covers the entire substrate. Growth of the IRMOF on the nanowire substrate allows for the film to be used in potential applications in sensing, membranes, photovoltaics, catalysis, and gas storage. We have also successfully used microwaves to rapidly produce these films with comparable film quality to our original method.

We report the synthesis and characterization of three cationic two-dimensional Nd(III)-based inorganic materials. The materials consist of [Nd2(OH)4(OH2)22+] layers with interlamellar α,ω-[−O3S(CH2)nSO3−] anions (n = 2–4). The materials were characterized by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy. As an initial example of anion exchange, all three materials show uptake of adipate, −O2C(CH2)4CO2−. These layered rare earth hydroxides show an increase in thermal stability with alkanedisulfonate chain length. The three polytypes expand the known chemistry for extended cationic inorganic materials using f-block metals.

Desulfurized JP-8 fuel is of great interest for use as the hydrogen feedstock of fuel cells. The refractory aromatic sulfur species present, however, are particularly challenging to remove through traditional methods. We report the first use of mesoporous silica nanoparticles (MSN) for desulfurization and the material displays a four-fold greater performance towards JP-8 fuel over previous sorbents. The bulk form of mesoporous silica shows three-fold greater level of desulfurization. Silver-impregnated nanoparticle and bulk MCM-41 were found to have saturation adsorption capacities of 32.6 mgS g−1 and 25.4 mgS g−1, respectively. MSN display a high capacity for the notoriously difficult to remove 4,6-dimethyldibenzothiophene along with a two-fold improvement in breakthrough capacity over previously published materials, of 0.98 mgS g−1 at 10 ppmwS.

We report the synthesis and characterization of a solid solution series of cationic metal–organic materials with full compositional range from pure Co(II) to Zn(II) end-members. The materials consist of [ZnxCo1–x(H2O)4(4,4′-bipy)2]2+ metal–organic clusters that π–π stack into 2-D positively charged layers, with the metal ratio tunable by molar ratio under hydrothermal conditions. The interlamellar α,ω-alkanedisulfonate serves as an anionic template and noncovalently interacts with the cationic layers. The weak interaction allows anion exchange for toxic oxometal anions, such as chromate, CrO42–. The highest chromate adsorption capacity was 68.5 mg/g (0.43 mol/mol) for the as-synthesized 50 mol % Co(II)-incorporated material. Our cationic material can also selectively trap these toxic oxo-anions when nontoxic anions (e.g., nitrate, sulfate) were present in an over 50-fold excess concentration.

We have successfully synthesized a rare example of an open framework nickel oxide with succinate capping the channels. A honeycomb-like layer of 14-membered rings centered in the (11) plane are connected by vertex-sharing NiO6 octahedra and water resides in the channels. The structure is only the second example of an extended inorganic–organic hybrid material containing 3-D Ni–O–Ni connectivity and was structurally characterized by single-crystal and powder X-ray diffraction. The material displays excellent chemical stability in aqueous solution from pH ∼ 1 to 13 and thermal stability to ∼375 °C as evidenced by thermogravimetric analysis coupled mass spectroscopy. The Ni2+ ions order ferromagnetically below Tc = 5.1 K and anisotropic exchange interactions lead to a field-induced metamagnetic transition and spin-glass-like dependence on cooling conditions in magnetic field.

A photoactive manganese nitrosyl, namely [Mn(PaPy(3))(NO)](ClO(4)) ({Mn-NO}), has been loaded into the columnar pores of an MCM-41 host. Strong interaction between the polar nitrosyl and the -OH groups on the host wall leads to excellent entrapment of the NO donor within the porous host. With the aluminosilicate-based host (Al-MCM-41), the loading is further enhanced due to electrostatic interaction of the cationic species with the aluminum sites. The extent of loading has been determined via analytical techniques including N(2) adsorption/desorption isometry. Powder X-ray diffraction studies on the loaded materials afford patterns typical of an ordered mesoporous silicate consisting of a hexagonal array of unidimensional channels (with slight loss of crystallinity). Elemental mapping of the loaded particles confirms the incorporation of {Mn-NO} into the porous MCM-41 structure and attests to the homogeneity of the guest molecule distribution throughout individual particles. When suspensions of the loaded materials in saline solution are exposed to low-power (10-100 mW) visible light, rapid release of NO is observed. With continuous exposure, a steady release of 50-80 μM of NO is attained with 5 mg of material/mL buffer within 5 min, and the NO flux is maintained for a period of ~60 min. Rapid bursts of 5-10 μM NO are noted with short light pulses. Loss of either the nitrosyl or its photoproduct(s) from these materials in biological media is minimal over long periods of time. The NO release profiles suggest potential use of these powdery biocompatible materials as NO donors where the delivery of NO (a strong antibiotic) could be controlled via the exposure of light. Such prediction has been confirmed with the successful eradication of both drug-susceptible and drug-resistant Acinetobacter baumannii in a soft-tissue infection model through light-triggered NO delivery.

A three-dimensional La(III) based metal-organic framework, La2[NC5H3(CO2)2]3·3H2O, was assembled using the aromatic linker 3,5-pyridinedicarboxylate. This new compound was synthesized hydrothermally and is an unusual example of a lanthanum containing metal-organic network. The compound contains two distinct La centers, each adopting a nine-coordinate geometry. The structure is built up from zig-zag chains that link via bridging water molecules into a double chain defining edge-sharing six rings. These double chains are arranged into layers and connect through 3,5-pyridinedicarboxylate ligands to give the extended 3-D coordination framework. The material is thermally stable to ca. 360 °C and transforms to an unknown compound before finally decomposing to phase-pure La2O3 at 800 °C. The synthesis, structure, morphology and properties of the new material are described.

This paper reports the synthesis, characterization, and application of two cationic bismuthate clusters by anion templating. The compounds were synthesized under mild hydrothermal treatment and characterized by powder and single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The first material consists of a cationic hexanuclear bismuthate cluster octahedral in geometry and linked by 1,2-ethanedisulfonate molecules. This structure is thermally stable to about 235 °C. In the second compound, discrete cationic nonanuclear bismuthate clusters interact electrostatically with trifluoromethanesulfonate anions to pack into a nearly layered assembly. The material undergoes a transformation to Bi2O3 upon loss of the triflate groups at about 385 °C. Both materials demonstrate the use of sulfonate groups for the anion-directed assembly of these rare cationic inorganic structures. The application of the 3D octahedral bismuth cluster material toward acidic heterogeneous catalysis is a...

We report the synthesis and characterization of two Ag(I)/Cu(I)-based cationic metal-organic frameworks and their application in both heterogeneous catalysis and anion exchange. The Cu(I)-based material was designed from our previously reported Ag(I) cationic topology. Both structures consist of cationic layers with pi-pi stacked chains of alternating metal and 4,4'-bipyridine. Alpha,omega-alkanedisulfonate serves as an anionic template, electrostatically bonding to the cationic layers. Due to weak interaction between the sulfonate template and cationic extended framework, both materials display reversible anion exchange for a variety of inorganic species. Indeed, the Ag(I)-based material exhibits highly efficient uptake of permanganate and perrhenate anion trapping, a model for pertechnetate trapping. The materials also display heterogeneous Lewis acidity, likely due to the coordinatively unsaturated metal sites which only bind to two bipy nitrogens and a weak interaction with one sulfonate oxygen. A comparative study on the influence of structure versus size selectivity and reusability for both exchange and catalysis is discussed.

We report a silver-based cationic metal−organic framework with two mixed organic linkers directing the structure. The structure consists of 1D Ag(4,4′-bipy) cationic chains arranged into close-packed layers. Weakly bound alkanedisulfonate anions charge-balance the layers, where only one oxygen of each sulfonate makes a long contact with the Ag. The unsaturated linear Ag centers likely allow the Lewis acidity displayed by the material for ketone protection as well as esterification. The material showed no reduction in yield after three catalytic runs with average 95% conversion yield for ketal formation and 57% for esterification without further water removal. In addition to hydrothermal conditions, the structure can be synthesized by reflux or room temperature, with almost identical catalytic ability. Other properties of this compound including chemical and thermal stability are also described.

Three rare examples of extended inorganic materials possessing a cationic charge on the host have been successfully synthesized hydrothermally. The first structure consists of two-dimensional lead fluoride [Pb9F16]2+ sheets with perchlorate anions occupying the interlayer space. The material is a higher symmetry polytype of our previously reported lead fluoride nitrate Pb3F5·NO3. Two new isoreticular layered metal−organic frameworks have also been discovered with cationic lead fluoride [Pb2F2]2+ layers pillared by 3- and 4-carbon chain alkylenedisulfonate molecules. Each structure was characterized by powder and single-crystal X-ray diffraction and thermogravimetric analysis. The thermal stability increases with the alkylene chain length of the linker molecule. The syntheses require the addition of perchloric acid to the reaction mixture. An improved synthesis for our previously reported lead fluoride polytype pillared by ethanedisulfonate in terms of increased yield and purity was also realized using per...

We describe herein a three-dimensional Cu(II) based metal−organic framework, copper hydroxide 2,6-naphthalenedisulfonate, Cu3(OH)4[C10H6(SO3)2]. The compound contains embedded positively charged 2-D copper oxide layers. This higher dimensionality of inorganic connectivity leads to far greater thermal stability (375 °C vs 245 °C) over our previously reported three-dimensional metal−organic framework containing embedded 1-D cuprate chains. Single crystal data for this material are as follows: FW = 544.92, monoclinic, space group P21/c, a = 13.549(5) A, b = 5.503(2) A, c = 9.512(4) A, β = 90.031(6)°, V = 709.2(5) A3, Dc = 2.552 g·cm−3, and Z = 4. The structure, crystallinity, morphology, and properties of the material are discussed. The magnetic susceptibility exhibits a broad maximum centered at 80 K, indicative of low-dimensional antiferromagnetic interactions. Control of inorganic dimensionality embedded within an MOF is an often overlooked yet key feature in determining the stability and important proper...

A three-dimensional Bi(III) based metal–organic framework was synthesized under hydrothermal conditions using the multidentate organic linker 3,5-pyridinedicarboxylate. Bismuth oxide 3,5-pyridinedicarboxylate, Bi2O2[NC5H3(CO2)2], contains embedded 1-D cationic bismuth oxide chains that propagate along the crystallographic c-axis. The oxygens of the Bi2O2 core are three-coordinate and bond strongly to the Bi atoms. Thermogravimetric analysis shows that the material possesses high thermal stability up ca. 400 °C before decomposing to phase-pure Bi2O3 at 800 °C. The structure, crystallinity, morphology and properties of the material are discussed.

We have discovered a rare example of a cationically charged inorganic material. The layered structure is an example outside the extensively studied isostructural set of anionic clays/layered double hydroxides and our previously reported lead fluoride nitrate. For the present compound, the antimony oxide hydroxide layers are positively charged and are templated by anionic alkylenedisulfonate. The organic molecules are only bonded electrostatically to the layers with sulfonate oxygen to antimony distances beyond the covalent range. The material catalyzes a ketal formation reaction as a Lewis acid without the need for drying the solvent before the reaction or a nonaqueous medium such as toluene. The catalyst is heterogeneous and is completely recovered after the catalysis for reapplication.

We report the capture of ppm-level aqueous perchlorate in record capacity and kinetics via the complete anion exchange of a cationic metal-organic framework. Ambient conditions were used for both the synthesis of silver 4,4'-bipyridine nitrate (SBN) and the exchange, forming silver 4,4'-bipyridine perchlorate (SBP). The exchange was complete within 90 min, and the capacity was 354 mg/g, representing 99% removal. These values are greater than current anion exchangers such as the resins Amberlite IRA-400 (249 mg/g), Purolite A530E (104 mg/g), and layered double hydroxides (28 mg/g). Moreover, unlike resins and layered double hydroxides, SBN is fully reusable and displays 96% regeneration to SBN in nitrate solution, with new crystal formation allowing the indefinite cycling for perchlorate. We show seven cycles as proof of concept. Perchlorate contamination of water represents a serious health threat because it is a thyroid endocrine disruptor. This noncomplexing anionic pollutant is significantly mobile and environmentally persistent. Removal of other anionic pollutants from water such as chromate, pertechnetate, or arsenate may be possible by this methodology.

We have discovered a metal−organic framework containing cationic inorganic layers. The metal fluoride−organodisulfonate structure, Pb2F2[C2H4(SO3)2], was synthesized hydrothermally. The lead fluoride cationic layers are covalently connected by 1,2-ethanedisulfonate chains oriented perpendicular to the layers. The material is thermally stable to ca. 325 °C, above which the material collapses to phase-pure α-PbF2. This material is a rare example of the use of organosulfonates as organic linker and the first metal−organic framework to contain lead fluoride connectivity. The existence of extended cationic inorganic moieties embedded within a metal−organic framework material further diversifies the possible structure types of this rapidly growing class of materials.

We report the synthesis and characterization of a seven coordinate europium complex, [EuCl3(C10H8N2O2) AE 2CH3OH]. The growing interest in developing efficient light conversion molecular devices (LCMDs) necessitates the need for new fluorescent materials. Ideal physicochemical properties of the materials include ligand absorption, efficient metal to ligand transfer, and strong luminescence with a relatively long decay time. The design of such material requires distinct absorbing (ligand) and emitting (metal ion) components. While Eu 3+ cation has a non-degenerate emitting level, 2,2 0 -bipyridine N,N dioxide is a heterocyclic ligand known to exhibit strong lumines

We describe a cationic erbium-based material [Er12(OH)29(H2O)5][O3SCH2CH2SO3]3.5·5H2O. As synthesized, the material is water stable and capable of complete organic anion exchange for a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange and as an analog for pharmaceutical waste, some of which have a carboxylate functionality at neutral pH range. Free-floating and partially anchored organosulfonate anions reside between the cationic corrugated layers and allow for exchange. The structure also displays a reversible hydration event above 100 °C. Both the as-synthesized and the exchanged materials are characterized by a variety of analytical techniques.

Elastomeric stamp deformation has been utilized for the contact printing (CP) of self-assembled monolayers (SAMs) and, more recently, polymers and proteins. Here, we take advantage of this well-studied phenomenon to fabricate a series of new metal thin-film patterns not present on the original stamp. The rounded patterns are of nanoscale thickness, long-range order, and are created from elastomeric stamps with only straight-edged features. The metal was printed onto the surface of an alpha,omega-alkanedithiol self-assembled monolayer (SAM). The new shapes are controlled by a combination of stamp geometry design and the application of external pressure. Previously published rules on stamp deformation for contact printing of SAMs are invalid because the coating is instead a thin-metal film. This method represents a new pathway to micropatterning metal thin films, leading to shapes with higher complexity than the original lithographic masters.

The first example of a unidimensional zirconium hydroxide fluoride was synthesized under mild solvothermal treatment and characterized by X-ray diffraction and thermal techniques. Monoprotonated ethylenediamine cations reside between the anionic chains. Crystal data for this material are as follows: [C2N2H9][Zr(OH)2F3], M=243.35, orthorhombic, space group Pca21, a = 6.8 0 1 6 ( 1 3 ) , b = 6.1 3 9 3 ( 1 2 ) , c = 1 4.8 6 7 ( 3 ) A , V = 6 2 0.8 ( 2 ) A 3 , T = 2 9 4 ( 2 ) K , Z = 4 , D c = 2.6 0 4 g cm - 3 , μ(Mo-Kα)=1.777 mm−1, λ = 0.7 1 0 7 3 A . The material transforms to an unknown layered material at ∼175 °C, a common occurrence for 1D structures where the chains are arranged in hydrogen-bonded layers and separated by interlayer organoammoniums. Collapse to the known condensed mineral phase Zr(FO)2.7 occurs at ca. 275 °C before finally transforming to the baddeleyite form of ZrO2 at ca. 460 °C.

We report the hydrothermal synthesis and characterization of a layered cobalt phenylphosphonate. Unlike most metal phosphonates reported to date, the structure was solved by single crystal X-ray diffraction (SC-XRD). Co(ii) centres are hexa-coordinated by oxygen and the octahedra corner-share into a layer. The layers are capped by phenylphosphonate groups, where the phenyl groups define a hydrophobic bilayer region. The material was also characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and SQUID (superconducting quantum interference device) magnetometry. The material undergoes an antiferromagnetic transition at a relatively low Néel temperature of 4.0 K, while the Curie-Weiss temperature of -76.5 K reflects the low-dimensionality of the magnetic structure. The effective magnetic moment of 5.01 micro(B) per Co(2+) verifies a high-spin configuration and an octahedral coordination of the metal centres. This layered material was correctly predicted in the literature from powder data, adds to the structural diversity of the cobalt phosphonates, and may be useful as an intercalation or exfoliation compound.

The hydrothermal inorganic reaction of cobalt chloride, tin oxalate and phosphoric acid yields a three-dimensional metal phosphate structure containing cobaltate layers. Hydrated tin phosphate chains connect the layers, defining unidimensional channels that contain occluded water molecules. Thermal and magnetic behaviour are also discussed. A cusp around 3.5 K and a negative Curie temperature of −35.9 K indicate antiferromagnetic exchange interactions between the Co(II) centers in the solid. The magnetic behavior follows the Curie–Weiss law in the 25–300 K range, with an effective magnetic moment of 3.18 μB.

Ceramic/self-assembled monolayer (SAM) bilayer coatings can provide adequate protection for silicon devices, or act as a multipurpose coating for other electronic applications, due to synergistic effects by forming a hybrid coating structure. The organic SAM layer acts as a “template” for the growth of the ceramic layer, while the ceramic layer can provide protection from environmental and mechanical impact. Low-temperature solution-based deposition techniques, namely, an in-situ solution method (biomimetic) and a hydrothermal method, have been employed in this study. Specifically, phosphonate-based (diethyl phosphatoethyl triethoxy silane) SAMs were used as a template to generate a zirconia ceramic layer at low temperatures. Other organic templates such as -SiCl3-, -OH-, -HSO3-, or -CH3-terminated SAMs were also examined. The reactions to grow the ceramic film were found to be pH sensitive. The ceramic and SAM coatings were characterized by a variety of analytical techniques. A pathway for the formation of the ceramic coating is also discussed.

A new compound, sodium tin trifluoride (NaSnF 3 , which we denote BING-12 for SUNY at Binghamton, Structure No. 12), was synthesized solvothermally from a pyridine–water solvent system. The new compound crystallized in the monoclinic space group C 2/ c (No. 15), with a =11.7429(12) A, b =17.0104(18) A, c =6.8528(7) A, β =100.6969(2)°, V =1345.1(2) A 3 and Z =16. The layered structure consists of outer pyramidal SnF 3 units, where the fluorides surround a central layer of six- and seven-coordinate sodium atoms. The layers are stabilized by charged Na + galleries that reside in the center of the layers. Tin trifluorophosphate (Sn 3 F 3 PO 4 , Compound 2 ) was isolated from a related synthetic system, and crystallized in the rhombohedral space group R 3 (No. 146), with a =11.8647(11) A, c =4.6291(6) A, V =564.34(10) A 3 and Z =3. The framework is made up of helical –Sn–F– chains, which are connected by phosphate groups. The materials were characterized by powder X-ray diffraction (PXRD), variable temperature PXRD (VT-PXRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM).

A solvothermal pyridine−HF−tin oxalate system has given rise to two new layered and one new chain crystal structures: BING-4, -7, and -8. BING-4 [SUNY at Binghamton, Structure No. 4, Sn(C2O4)(C5H5N), triclinic, P-1, a = 5.4202(6) A, b = 8.3824(9) A, c = 9.3506(10) A, α = 87.982(2)°, β = 87.916(2)°, γ = 85.650(2)°, Z = 2] consists of charge-neutral chains of alternating tin and oxalate groups, with pyridine molecules completing the fifth coordination of the tin centers and capping the chains. Both BING-7 ([Sn(C2O4)F-][NH4+], monoclinic, P21/c, a = 8.2736(4) A, b = 9.6386(5) A, c = 7.7473(4) A, β = 111.229(1)°, Z = 4) and BING-8 ([Sn(PO4H)F-][NH4+], orthorhombic, Pnma, a = 6.6789(4) A, b = 5.3402(4) A, c = 15.2795(10) A, Z = 4) are anionic, fluorinated, tin oxalate and tin phosphate layers, respectively, with interlamellar charge-balancing ammonium cations. Characterization methods included single-crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), in-situ variable temperature (VT) PXRD, t...

Our research involves the development of new cationic materials for anion-based applications. We report the solvothermal synthesis and characterization of Pb(3)F(5)NO(3), a new layered lead fluoride material that, unlike the majority of layered and open-framework materials, is cationic in charge. The structure consists of polyhedral lead centers connected by doubly and triply bridging fluoride groups. We quantitatively exchanged the interlamellar nitrate groups of Pb(3)F(5)NO(3) for dichromate, under ambient aqueous conditions. Nuclear magnetic resonance and UV-vis spectroscopy show the reaction proceeds to 61.0% completion in several days. The material is also stable to 450 degrees C, which is vastly superior to organic resins that are still the standard for anion-exchange. The presence of extraframework anions also opens up other potentially unique anion-based properties, such as new catalytic reactions, anion intercalation, or growth of anionic clusters within the void spaces of the cationic material.

This paper demonstrates the use of poly(dimethylsiloxane) (PDMS), polyurethane (PU), epoxy, and poly(methyl methacrylate) (PMMA) as mandrils to fabricate metallic heat exchangers having 300-700 /spl mu/m internal channels. The mandrils were prepared using two soft lithographic techniques-replica molding and microembossing. To fabricate the heat exchangers, the polymeric mandrils were coated with a thin layer of metal by thermal evaporation or sputtering; this layer acted as the cathode for electrodeposition of a shell of nickel or copper that was 100 /spl mu/m thick. The polymers were removed by burning them out at 400/spl deg/C in air, or by dissolving them with a tetrahydrofuran solution of tetrabutylammonium fluoride. Studies of heat dissipation showed that the nickel heat exchangers with features that range in size from 150-750 /spl mu/m have thermal resistances ranging from 0.07 to 0.12/spl deg//sup -2/C W/sup -1/ cm at flow rates of water of /spl sim/20 L h/sup -1/ and pressures of 8.6-83/spl times/10/sup 3/ N m/sup -2/.

This paper describes the self-assembly of hexagonal plates (with 2.7 mm wide sides) at the interface between perfluorodecalin (PFD) and water. All 14 different hexagons that can be made by permuting the number and location of the hydrophobic and hydrophilic faces were examined. The plates attracted one another by lateral capillary forces involving the menisci on the hydrophilic faces. The plates were made of poly(dimethylsiloxane) (PDMS) containing aluminum oxide and had a density of 1.86 g/cm3, close to the density of PFD (ρ = 1.91 g/cm3). This work complements a previous paper (Bowden, N.; Choi, I. S.; Grzybowski, B. A.; Whitesides, G. M. J. Am. Chem. Soc. 1999, 121, 5373) that examined the self-assembly of hexagonal plates of PDMS (ρ = 1.05 g/cm3) that had a density close to that of water, and were attracted through menisci on the hydrophobic faces. The arrays that formed from the heavy (ρ = 1.86 g/cm3) hexagons with a particular pattern of hydrophilic faces were analogous to the arrays that formed fro...