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A facile and sustainable synthetic strategy based on the coordination of natural polyphenols with metal ions is developed for the textural engineering of mesocrystals and hierarchical carbon nanomaterials. The desired control of coordination between ellagic acid and zinc ions enables the macroscopic self-assembly behavior of crystalline nanoplatelets to be tailored into round and elongated "peanut"-like micron-sized mesostructured particles. Direct carbonization of these mesocrystals generates hierarchically porous carbon particles in good yields, possessing bimodal micro- and mesoporous architecture along with a well-preserved macroscopic structure. The pore system provides both small storage sites, demonstrated by high CO2 uptake, and transport channels also accessible by larger molecules. [ABSTRACT FROM AUTHOR]

The realization of nanodevices with advanced functions requires the development of new and efficient approaches for the combination of the very small building blocks into desired structures. Self-assembly through noncovalent interactions is an effective technique that has been proven successful in forming different nanoparticle assembly motifs. The importance of understanding factors governing the creation of nanoparticle assembly stems from the desire to precisely optimize the functional properties of the nanostructures for optical, microelectronic, magnetic, catalytic, and chemical biological applications. Recently, a new solvent system, room-temperature ionic liquids (RTILs), has developed to a focal point of interest in both academia and industry. RTILs are organic salts with low melting points.

Mesocrystals -- superstructures of crystalline nanoparticles that are aligned in a crystallographic fashion -- are of increasing interest for formation of inorganic materials with complex and sophisticated morphologies to tailor properties without changing chemical composition. Here we report morphogenesis of a novel mesocrystal consisting of nanoscale metal -- organic frameworks (MOF) by using double hydrophilic block copolymer (DHBC) as a crystal modulator. DHBC selectively prefers the metastable hexagonal kinetic polymorph and promotes anisotropic crystal growth to generate hexagonal rod mesocrystals via oriented attachment and mesoscale assembly. The metastable nature of hexagonal mesocrystals enables further hierarchical morphogenesis by a solvent-mediated polymorphic transformation toward stable tetragonal mesocrystals that retain the outer hexagonal particle morphology. Furthermore, synthesis of hybrid MOFs, where hexagonal mesocrystals are vertically aligned on specific surfaces of cubic MOFs, is demonstrated. The present strategy opens a new avenue to create MOF mesocrystals and their hybrids with controlled size and morphology that can be designed for various potential applications. [ABSTRACT FROM AUTHOR]

Lignin from biomass can become a sustainable source of aromatic compounds. Its depolymerization can be accomplished through hydrogenolysis, although the development of catalysts based on cheap and abundant metals is lacking. Herein, a sustainable composite based on titanium nitride and nickel is synthesized and employed as catalyst for the hydrogenolysis of aryl ethers as models for lignin. The catalytic activity of the new material during hydrogenation reactions is proven to be superior to that of either component alone. In particular, different aryl ethers could be efficiently converted under relatively mild conditions into aromatic compounds and cycloalkanes within minutes. [ABSTRACT FROM AUTHOR]

A facile, template-free synthetic route is reported toward poly(ionic liquid) complexes (PILCs) which for the first time exhibit stable micro-/mesoporous structure. This is accomplished via in situ ionic complex- ation between imidazolium-based PILs and poly(acrylic acid) in various alkaline organic solvents. The PILC can be highly loaded with copper salts and can be used as a catalytic support for effective aerobic oxidation of activated hydrocarbons under mild conditions. [ABSTRACT FROM AUTHOR]

Mesoporous nitrogen-doped carbon materials with high surface areas up to 1500 m² g-1 were conveniently made by the carbonization of nucleobases dissolved in an all-organic ionic liquid (1-ethyl-3-methylimidazolium dicyanamide). Using hard templating with silica nanoparticles, this process yields high- surface-area nitrogen-doped carbon, materials with nitrogen contents as high as 12 wt %, narrow mesopore size distribution of ca. 12 nm diameter, and local graphitic carbon structure. It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells. Specifically, the as-prepared materials exhibit a low onset voltage for OAR in alkaline medium and a high methanol tolerance, compared with those of commercial 20 wt % Pt/C catalyst. We regard this as a first step toward an all-sustainable fuel cell, avoiding noble metals. [ABSTRACT FROM AUTHOR]

A facile and sustainable synthesis of hollow carbonaceous nanospheres is presented, offering a scalable and multifunctional route to the generation of useful nanocontainers, which critically possess the stability not offered by polymeric equivalents and functionality not afforded by other nanocarbons. Carbonization temperature provides a subtle but elegant mechanism to control structure and thereby hydrophobicity, nanopartitioning, and permeation between the inner and outer space. [ABSTRACT FROM AUTHOR]

Here, we present a systematic study on the influence of the bioligand deferoxamine mesylate on the crystallization and assembly behavior of tungsten oxide in a soft-chemistry process. Without deferoxamine mesylate, this approach yields pseudo-single crystalline tungstite nanoplatelets consisting of a large number of crystallographically almost perfectly aligned primary crystallites. In the presence of a constant amount of deferoxamine, the particle morphology drastically changes with temperature, ranging from wormlike organic-inorganic hybrid nanostructures to single-crystalline tungsten oxide nanowires, highlighting the role of the bioligand in controlling the crystal growth and assembly behavior. The nanowires have a uniform diameter of about 1.3 nm, an aspect ratio of more than 500, and the structural flexibility of tungsten oxide. The presented process is based on the combination of biomimetic construction principles with nonaqueous sol-gel chemistry, thus combining the advantages of both tools, excellent control over particle morphology and high crystallinity at low temperature. [ABSTRACT FROM AUTHOR]

A widely applicable solvothermal route to nanocrystalline iron, indium, gallium, and zinc oxide based on the reaction between the corresponding metal acetylacetonate as metal oxide precursor and benzylamine as solvent and reactant is presented. Detailed XRD, TEM, and Raman studies prove that, with the exception of the iron oxide system, where a mixture of the two phases magnetite and maghemite is formed, only phase pure materials are obtained, γ -Ga2O3, zincite ZnO, and cubic ln2O3. The particle sizes lie in the range of 15-20 nm for the iron, 10-15 nm for the indium, 2.5-3.5 nm for gallium, and around 20 nm for zinc oxide. GC-MS analysis of the final reaction solution after removal of the nanoparticles showed that the composition is rather complex consisting of more than eight different organic compounds. Based on the fact that N-isopropylidenebenzylamine, 4-benzylamino-3-penten-2-one, and N-benzylaceta-mide were the main species found, we propose a detailed formation mechanism encompassing solvolysis of the acetylacetonate ligand, involving C-C bond cleavage, as well as ketimine and aldol-like condensation steps. [ABSTRACT FROM AUTHOR]

PoIy[2-(acetoacetoxy)ethyl methacrylate] (PAEMA) homopolymers were found to self-assemble into hierarchical superstructures, that is, double-stranded helical tubes of either screw sense (scanning force microscopy). Both the diameter and the pitch of the superhelices are ∼12 nm, and their length is 200-500 nm. It is proposed that PAEMA chains first organize into ribbons, the width of which determines the pitch of the helix, and then coil up into the helical superstructure. The formation of these structures is driven by the establishment of hydrogen-bridging interactions between adjacent acetoacetoxy groups (NMR and dielectric relaxation spectroscopy) and compensation of dipole moments. [ABSTRACT FROM AUTHOR]

Describes the formation of polymer vesicles by polybutadiene-block-poly (L-glutamate)s copolymers. Detection of the vesicular structure by dynamic light scattering; Importance of the amphiphilic block copolymers in supramolecular polymer chemistry; Use of the polymers in drug delivery.

The ability to synthesize a broad spectrum of metal clusters (MCs) with their size controllable on a subnanometer scale presents an enticing prospect for exploring nanosize-dependent properties. Here we report an innovative design of a capping agent from a polytriazolium poly(ionic liquid) (PIL) in a vesicular form in solution that allows for crafting a variety of MCs including transition metals, noble metals, and their bimetallic alloy with precisely controlled sizes (~1 nm) and record-high catalytic performance. The ultrastrong stabilization power is a result of an unusual synergy between the conventional binding sites in the heterocyclic cations in PIL and an in situ generated polycarbene structure induced simultaneously to the reduction reaction. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts of inexpensive and reusable transition-metal are attractive alternatives to homogeneous catalysts; the relatively low activity of transition-metal nanoparticles has become the main hurdle for their practical applications. Here, the de novo design of a Mott-Schottky-type heterogeneous catalyst is reported to boost the activity of a transition-metal nanocatalyst through electron transfer at the metal/nitrogen-doped carbon interface. The Mott-Schottky catalyst of nitrogen-rich carbon-coated cobalt nanoparticles (Co@NC) was prepared through direct polycondensation of simple organic molecules and inorganic metal salts in the presence of g-C3N4 powder. The Co@NC with controllable nitrogen content and thus tunable Fermi energy and catalytic activity exhibited a high turnover frequency (TOF) value (8.12 mol methyl benzoate mol-1 Co h-1) for the direct, base-free, aerobic oxidation of benzyl alcohols to methyl benzoate; this TOF is 30-fold higher than those of the state-of-the-art transition-metal-based nanocatalysts reported in the literature. The presented efficient Mott-Schottky catalyst can trigger the synthesis of a series of alkyl esters and even diesters in high yields. [ABSTRACT FROM AUTHOR]

The article reports that carbon nitrides can be reversibly protonated by strong acids, modifying dispersibility or solubility, electronic structure and surface area. Preparation of new series of g-C,3N 4 based functional hybrid materials via counteranion exchange. The study shows that the high surface area could be preserved after recovery by heating and enables improved sintering which allowed direct measurement of its photoconductivity.

This article focuses on mesocrystals and morphology change of CaCO3 crystals in the presence of a polyelectrolyte additive. Crystallization control is one of the most important techniques of preparation, purification, and application of solid substances, making it an intensely studied field. Besides conventional crystallization, there are also nonclassical pathways of crystallization via colloidal intermediates and mesoscale transformation, in which crystalline structures are constructed and/or transformed from larger units instead of single ions. The authors present a simple system of calcite paired with polystyrene sulfonate, which undergoes mesocrystal formation. Appropriate concentration adjustment of both partners allows broad, systematic variation of the mesocrystal morphology that demonstrates long-range interactions. Moreover, the authors reports that selective coding of nanocrystal surfaces by polymers can not only lead to mesocrystals exposing unusual crystal faces in their superstructure, but also can form self-assembled structures with changed symmetry.

The synthesis of vertically aligned functional graphitic carbon nanosheets (CNS) is challenging. Herein, we demonstrate a general approach for the fabrication of vertically aligned CNS and metal carbide@CNS composites via a facile salt templating induced self-assembly. The resulting vertically aligned CNS and metal carbide@CNS structures possess ultrathin walls, good electrical conductivity, strong adhesion, excellent structural robustness, and small particle size. In electrochemical energy conversion and storage such unique features are favorable for providing efficient mass transport as well as a large and accessible electroactive surface. The materials were tested as electrodes in a lithium ion battery and in electrochemical water splitting. The vertically aligned nanosheets exhibit remarkable lithium ion storage properties and, concurrently, excellent properties as electrocatalysts for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Herein we report a general liquid-mediated pathway for the growth of continuous polymeric carbon nitride (C3N4) thin films. The deposition method consists of the use of supramolecular complexes that transform to the liquid state before direct thermal condensation into C3N4 solid films. The resulting films exhibit continuous porous C3N4 networks on various substrates. Moreover, the optical absorption can be easily tuned to cover the solar spectrum by the insertion of an additional molecule into the starting complex. The strength of the deposition method is demonstrated by the use of the C3N4 layer as the electron acceptor in a polymer solar cell that exhibits a remarkable open-circuit voltage exceeding 1 V. The easy, safe, and direct synthesis of carbon nitride in a continuous layered architecture on different functional substrates opens new possibilities for the fabrication of many energy-related devices. [ABSTRACT FROM AUTHOR]

Here we report a new and simple synthetic pathway to form ordered, hollow carbon nitride structures, using a cyanuric acid–melamine (CM) complex in ethanol as a starting product. A detailed analysis of the optical and photocatalytic properties shows that optimum hollow carbon nitride structures are formed after 8 h of condensation. For this condensation time, we find a significantly reduced fluorescence intensity and lifetime, indicating the formation of new, nonradiative deactivation pathways, probably involving charge-transfer processes. Enhanced charge transfer is seen as well from a drastic increase of the photocatalytic activity in the degradation of rhodamine B dye, which is shown to proceed via photoinduced hole transfer. Moreover, we show that various CM morphologies can be obtained using different solvents, which leads to diverse ordered carbon nitride architectures. In all cases, the CM-C3N4 structures exhibited superior photocatalytic activity compared to the bulk material. The utilization of CM hydrogen-bonded complexes opens new opportunities for the significant improvement of carbon nitride synthesis, structure, and optical properties toward an efficient photoactive material for catalysis. [ABSTRACT FROM AUTHOR]

Nanoporous polyelectrolyte membranes with hierarchical and unique pore architectures can be readily made via electrostatic complexation between imidazolium-based poly(ionic liquid)s and poly(acrylic acid) in a variety of morphologies. Coating the membrane onto the surface of an optical fiber resulted in a device with high pH-sensing performance in terms of the response rate and the sensitivity, due to the charge and porous nature of the membrane layer. [ABSTRACT FROM AUTHOR]

Mesoporous nitrogen-doped carbon derived from the ionic liquid N-butyl-3-methylpyridinium dicyanamide is a highly active, cheap, and selective metal-free catalyst for the electrochemical synthesis of hydrogen peroxide that has the potential for use in a safe, sustainable, and cheap flow-reactor-based method for H2O2 production. [ABSTRACT FROM AUTHOR]

This paper reports on the highly ordered and tunable inner structure of poly(ionic liquid) nanoparticles, which formed spontaneously by precipitation polymerization from water. Without added stabilizer, these "latexes" are much smaller (20-40 nm in diameter) than usual polymer latexes and exhibit either multilamellar or unilamellar vesicular morphology, depending on the tail length of the quaternizing alkyl chains. The simplicity in the synthesis and composition and the high complexity of the ordered structures that resemble liposomes expand the classical profile of homopolymer self-assembly. In addition, unidirectional superassembly to a nanoworm mesostructure is found at elevated concentrations, indicating that the ionic liquid liposomes are apt to integrate into further hierarchical assembly schemes. [ABSTRACT FROM AUTHOR]

Graphene sheet/polymeric carbon nitride nanocomposite (GSCN) functions as a metal-free catalyst to activate O2 for the selective oxidation of secondary C-H bonds of cyclohexane. By fine-tuning the weight ratio of graphene and carbon nitride components, GSCN offers good conversion and high selectivity to corresponding ketones. Besides its high stability, this catalyst also exhibits high chemoselectivity for secondary C-H bonds of various saturated alkanes and, therefore, should be useful in over- coming challenges confronted by metal-mediated catalysis. [ABSTRACT FROM AUTHOR]

A simple, high yield, chemical process is developed to fabricate layered h-BN nanosheets and BCNO nano-particles with a diameter of ca. 5 nm at 700 °C. The use of the eutectic LiCl/KCl salt melt medium enhances the kinetics of the reaction between sodium borohydride and urea or guanidine as well as the dispersion of the nanoparticles in water. The carbon content can be tuned from 0 to 50 mol % by adjusting the reactant ratio, thus providing precise control of the light emission of the particles in the range 440-528 nm while reaching a quantum yield of 26%. Because of their green synthesis, low toxicity, small size, and stability against aggregation in water, the as-obtained photoluminescent BCNO nanoparticles show promise for diagnostics and optoelectronics. [ABSTRACT FROM AUTHOR]

The principle of polymer-controlled crystallization of inorganic materials has been successfully transferred to functional aromatic organic dyes, in this instance 3,4,9,10-perylenetetracarboxylic acid potassium salt (PTCAPS), after its single-crystal structure was determined. The cationic double hydrophilic block copolymer poly(ethylene glycol)-block-branched-poly(ethyleneimine) (PEG-b-PEI) was used as the polymer additive to modify the crystallization of PTCAPS. Ultralong hierarchically structured PTCAPS microbelts with constant width and thickness of each individual belt have been fabricated. The belts are a mesocrystalline assembly of primary nanoparticles with high-energy anionic {001} faces stabilized by polymer complexation. Polarization microscopy, X-ray diffraction, optical absorption spectra, and fluorescence spectra indicate the favorable orientation of the 1D microbelts in the close-stacking direction and reveal a specific 1 D superstructure fluorescence. Electrical conductivity measurements performed on a single nanobelt disclose in the doped state a remarkably high electronic conductivity and further demonstrate extended, wirelike π-π interactions along the [020] long axis of the belts. Together with the very large length of the belts and their organic-organic hybrid nanostructure, this makes these organic wires potentially interesting for the field of nano-/micro-optoelectronics. [ABSTRACT FROM AUTHOR]

Abstract: High surface area organic materials featuring both micro- and mesopores were synthesized under ionothermal conditions via the formation of polyaryltriazine networks. While the polytrimerization of nitriles in zinc chloride at 400 °C produces microporous polymers, higher reaction temperatures induce the formation of additional spherical mesopores with a narrow dispersity. The nitrogen-rich carbonaceous polymer materials thus obtained present surface areas and porosities up to 3300 m[sup2] g[sup-1] and 2.4 cm[sup3] g[sup-1], respectively. The key point of this synthesis relies on the occurrence of several high temperature polymerization reactions, where irreversible carbonization reactions coupled with the reversible trimerization of nitriles allow the reorganization of the dynamic triazine network. The ZnCl[sub2] molten salt fulfills the requirement of a high temperature solvent, but is also required as catalyst. Thus, this dynamic polymerization system provides not only highly micro- and mesoporous materials, but also allows controlling the pore structure in amorphous organic materials. [ABSTRACT FROM AUTHOR]

A novel nonaqueous route for the preparation of nanocrystalline BaTiO3, SrTiO3, and (Ba,Sr)- TiO3 has been developed. In a simple one-pot reaction process, the elemental alkaline earth metals are directly dissolved in benzyl alcohol at slightly elevated temperatures. After the addition of Ti(O'Pr)4, the reaction mixture is heated to 200 °C, resulting in the formation of a white precipitate. XRD measurements prove the exclusive presence of the perovskite phase without any other crystalline byproducts such as BaCO3 or TiO2. TEM investigations reveal that the BaTiO3 nanoparticles are nearly spherical in shape with diameters ranging from 4 to 5 nm. The SrTiO3 particles display less uniform particle shapes, and the size varies between 5 and 10 nm. Lattice fringes observed in HRTEM measurements further prove the high crystallinity of the nanoparticles. Surprisingly, GC-MS analysis of the reaction solution after hydrothermal treatment shows that hardly any ether formation occurs during the BaTiO3 synthesis. Instead, the presence of 4-phenyl-2-butanol in stoichiometric amounts gives evidence that the formation mechanism proceeds mainly via a novel pathway involving C-C bond formation between benzyl alcohol and the isopropanolate ligand. [ABSTRACT FROM AUTHOR]

Mesoporous carbon nitride (mpg-C3N4) polymer can function as a metal-free photocatalyst to activate O2 for the selective oxidation of benzyl alcohols with visible light, avoiding the cost, toxicity, and purification problems associated with corresponding transition-metal systems. By combining the surface basicity and semiconductor functions of mpg-C3N4, the photocatalytic system can realize a high catalytic selectivity to generate benzaldehyde. The metal-free photocatalytic system also selectively converts other alcohol substrates to their corresponding aldehydes/ketones, demonstrating a potential pathway of accessing traditional mild radical chemistry with nitroxyl radicals. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the impact of phosphorus(P)-doped carbon nitride solid to enhance conductivity and photocurrent generation. The study selects ionic liquids as a mild P-doping source where structure and texture were evaluated by x-ray diffraction. Results of the study show that P-doping carbon nitride increases electric conductivity by up to 4 orders and photocurrent generation by a factor of up to 5 orders of magnitude.

The article discusses the oxidation catalysis of benzene to phenol compounds through hydrogen peroxide and light irradiation. It examines the formation of phenol enhanced by visible light irradiation. It notes the significance of oxophilic ionic iron elements for the enhancement of phenol production form benzene. Furthermore, it also provides an analysis of the elements as a product from the catalytic reaction.