Synthesis Of Inorganic Materials Research Articles

Soft Vesicles in the Synthesis of Hard Materials

Vesicles of surfactants in aqueous solution have received considerable attention because of their use as simple model systems for biological membranes and their applications in various fields including colloids, pharmaceuticals, and materials. Because of their architecture, vesicles could prove useful as "soft" templates for the synthesis of "hard materials". The vesicle phase, however, has been challenging and difficult to work with in the construction of hard materials. In the solution-phase synthesis of various inorganic or macromolecular materials, templating methods provide a powerful strategy to control the size, morphology, and composition of the resulting micro- and nanostructures. In comparison with hard templates, soft templates are generally constructed using amphiphilic molecules, especially surfactants and amphiphilic polymers. These types of compounds offer advantages including the wide variety of available templates, simple fabrication processes under mild conditions, and easy removal of the templates with less damage to the final structures. Researchers have used many ordered molecular aggregates such as vesicles, micelles, liquid crystals, emulsion droplets, and lipid nanotubes as templates or structure-directing agents to control the synthesis or assembly hard micro- and nanomaterials composed from inorganic compounds or polymers. In addition to their range of sizes and morphologies, vesicles present unique structures that can simultaneously supply different microenvironments for the growth and assembly of hard materials: the inner chamber of vesicles, the outer surface of the vesicles, and the space between bilayers. Two main approaches for applying vesicles in the field of hard materials have been explored: (i) in situ synthesis of micro- or nanomaterials within a specific microenvironment by vesicle templating and (ii) the assembly or incorporation of guest materials during the formation of vesicles. This Account provides an in-depth look at the research concerning the association of soft vesicles with hard materials by our laboratory and others. We summarize three main principles of soft vesicle usage in the synthesis of hard materials and detailed procedures for vesicle templating and the characterization of the synthetic mechanisms. By use of these guiding principles, a variety of inorganic materials have been prepared, such as quantum dots, noble metal nanoparticles, mesoporous structures, and hollow capsules. Polymerization within the vesicle bilayers enhances vesicle stability, and this strategy has been developed to synthesize hollow polymer materials. Since 2004, our group has pursued a completely different strategy in the synthesis of micro- and nanomaterials using vesicles as reactive templates. In this method, the vesicles act not only as templates but also as reactive precursors. Because of the location of metal ions on the bilayer membranes, such reactions are restricted to the interface of the vesicle membrane and solution. Finally, using the perspective of soft matter chemistry, we stress some basic criteria for vesicle templating.

Insights into the Self-Assembly Mechanism of the Modular Polyoxometalate “Keggin-Net” Family of Framework Materials and Their Electronic Properties

The mechanism for the syntheses of inorganic framework materials based solely on polyoxometalate Keggin clusters has been examined and their electronic properties have been investigated. The assembly of the modular network compounds with the molecular formula (C4H10NO)n[W72M12O268X7] (with the heteroatom X = Si or Ge and the heterometal M = Co(II) or Mn(III)) is based on the isomerization of the metastable precursor material [γ-XW10O36]8–, followed by the inclusion of the heterometal and subsequent assembly into the extended framework structure. The two frameworks featuring manganese substitution can be dis- and reassembled in a recrystallization process while the cobalt versions do not show comparable behavior. The intrinsic differences of the four compounds with regards to their heteroatom and heterometal substitution are shown in terms of their redox behavior.

Influence of zinc on the calcium carbonate biomineralization of Halomonas halophila

BackgroundThe salt tolerance of halophilic bacteria make them promising candidates for technical applications, like isolation of salt tolerant enzymes or remediation of contaminated saline soils and waters. Furthermore, some halophilic bacteria synthesize inorganic solids resulting in organic–inorganic hybrids. This process is known as biomineralization, which is induced and/or controlled by the organism. The adaption of the soft and eco-friendly reaction conditions of this formation process to technical syntheses of inorganic nano materials is desirable. In addition, environmental contaminations can be entrapped in biomineralization products which facilitate the subsequent removal from waste waters. The moderately halophilic bacteria Halomonas halophila mineralize calcium carbonate in the calcite polymorph. The biomineralization process was investigated in the presence of zinc ions as a toxic model contaminant. In particular, the time course of the mineralization process and the influence of zinc on the mineralized inorganic materials have been focused in this study.ResultsH. halophila can adapt to zinc contaminated medium, maintaining the ability for biomineralization of calcium carbonate. Adapted cultures show only a low influence of zinc on the growth rate. In the time course of cultivation, zinc ions accumulated on the bacterial surface while the medium depleted in the zinc contamination. Intracellular zinc concentrations were below the detection limit, suggesting that zinc was mainly bound extracellular. Zinc ions influence the biomineralization process. In the presence of zinc, the polymorphs monohydrocalcite and vaterite were mineralized, instead of calcite which is synthesized in zinc-free medium.ConclusionsWe have demonstrated that the bacterial mineralization process can be influenced by zinc ions resulting in the modification of the synthesized calcium carbonate polymorph. In addition, the shape of the mineralized inorganic material is chancing through the presence of zinc ions. Furthermore, the moderately halophilic bacterium H. halophila can be applied for the decontamination of zinc from aqueous solutions.

Controlled synthesis, growth mechanism and highly efficient solar photocatalysis of nitrogen-doped bismuth subcarbonate hierarchical nanosheets architectures

The synthesis and self-assembly of hierarchical architectures from nanoscale building blocks with unique morphology, orientation and dimension have opened up new opportunities to enhance their functional performances and remain a great challenge. This work represents tunable synthesis of various types of 3D monodisperse in situ N-doped (BiO)(2)CO(3) hierarchical architectures composed of 2D single-crystal nanosheets with dominant (001) facets by a one-pot template-free hydrothermal method from bismuth citrate and ammonia solution. Depending on the concentration of ammonia solution, the morphology of N-doped (BiO)(2)CO(3), including dandelion-like, hydrangea-like and peony flower-like microspheres, can be selectively constructed due to different self-assembly patterns of nanosheets. It was revealed that the ammonia played dual roles in the formation of N-doped (BiO)(2)CO(3) architectures. One is to hydrolyze bismuth citrate, and the other is to behave as a nitrogen doping source. The in situ doped nitrogen substituted for oxygen in (BiO)(2)CO(3) and subsequently narrowed the band gap, making N-doped (BiO)(2)CO(3) visible light active. Due to the special nanosheets architectures, the prepared various N-doped (BiO)(2)CO(3) materials exhibited especially efficient photocatalytic activity and high durability for the removal of NO in air under both visible and UV light irradiation. Based on the direct observation of the growth process with respect to phase structure, chemical composition and morphological structure, a novel growth mechanism is revealed, which involves a unique multistep pathway, including reaction-nucleation, aggregation, crystallization, dissolution-recrystallization, and Ostwald ripening. The facile synthesis approach and the proposed growth mechanism could provide new insights into the design and controlled synthesis of inorganic hierarchical materials with new or enhanced properties.

Self-assembly of amorphous calcium carbonate microlens arrays

Biological materials are often based on simple constituents and grown by the principle of self-assembly under ambient conditions. In particular, biomineralization approaches exploit efficient pathways of inorganic material synthesis. There is still a large gap between the complexity of natural systems and the practical utilization of bioinspired formation mechanisms. Here we describe a simple self-assembly route leading to a CaCO3 microlens array, somewhat reminiscent of the brittlestars' microlenses, with uniform size and focal length, by using a minimum number of components and equipment at ambient conditions. The formation mechanism of the amorphous CaCO3 microlens arrays was elucidated by confocal Raman spectroscopic imaging to be a two-step growth process mediated by the organic surfactant. CaCO3 microlens arrays are easy to fabricate, biocompatible and functional in amorphous or more stable crystalline forms. This shows that advanced optical materials can be generated by a simple mineral precipitation.

Synthesis and Polymerization of Substituted Ammonium Sulfonate Monomers for Advanced Materials Applications

Sulfonated polymers have found use as ion-exchange membranes for use in fuel cells, water purification, electroactive devices, and inorganic materials templating and synthesis. Improving the materials for these applications and opening up new applications requires the ability to synthesis targeted or more complex sulfonated polymers, which includes tailoring the chemistry (copolymerization across a wider range of solubility) and/or polymer architecture (block, graft, nanoparticle). This article will summarize the recent work using sulfonated monomers with substituted ammonium counterions as a versatile route for enabling this goal. Two main benefits of these monomers are as follows. First, they are useful for preparing amphiphilic copolymers, which is a challenge using traditional acidic or alkali salt forms of sulfonated monomers. Second, sulfonated polymers with substituted ammonium counterions are useful polymers for obtaining unique material properties, such as organo-gelation of low polarity solvents or obtaining ionic liquid polymers for the fabrication of solid polymer electrolytes.

Novel Cubic Magnetite Nanoparticle Synthesis Using Room Temperature Ionic Liquid

Room Temperature Ionic liquids are relatively more useful in the synthesis of inorganic nanostructured materials because of their unique properties. To synthesize the iron oxide nanoparticle in simple precipitation method, a novel ionic liquid was used as the greener medium and stabilizing agent namely “1‐n‐butyl‐3‐methylimidazolium trifluoromethane sulfonate [BMIM][TfO]”. The crystallinity, chemical structure, morphology and magnetic properties of the synthesized magnetite nanoparticles have been characterized by using X‐ray diffraction (XRD), Fourier Transform Infrared (FT‐IR), Scanning electron microscopy (SEM), Atomic force microscopy(AFM), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) studies. The XRD study is divulge that the synthesized magnetite nanoparticles have inverse spinel face centered cubic structure. The FT‐IR vibration peaks show the formation of Fe3O4 nanoparticles, where the vibration peak for Fe‐O is deliberately presence at 584 cm-1. The average particle size of the synthesized nanoparticles is found to be 35 nm. Homogeneously dispersed cubic shape with superstructure is found through SEM, AFM and TEM examination studies. The synthesized iron oxide nanoparticles have a high saturation magnetization value of 25 emu/g, which is very much useful for biomedical applications.

Sonochemical Synthesis of Cu3(BTC)2in a Deep Eutectic Mixture of Choline Chloride/dimethylurea

Metal organic frameworks (MOFs) are a class of porous polymeric material composed of metal ions or clusters linked together by organic bridging ligands. Their large surface areas accompanied by uniform pores, open metal sites, and diverse available post-synthesis functionalization routes make MOFs promising candidate materials for gas storage, separation, and heterogeneous catalysis. MOFs are typically synthesized by solvothermal reactions in organic solvents or in water, but have also been prepared in ionic liquids (ILs) recently; examples of the latter include Cu-BTC (BTC: 1,3,5-benzenetricarboxylate), Ln-BTC, Cd-BTC, Zn-BTC, and others. ILs have been attracting increasing attention as a solvent of choice for chemical synthesis, because of their unique integration of various properties such as essentially zero vapor pressure, excellent solvating properties, easy recyclability, and high thermal stability. The majority of the reports dealing with MOF synthesis have focused on ILs derived from 1-alkyl-3-methylimidazolium. However, deep eutectic solvents (DESs), mixtures of two or more compounds that have melting points lower than that of either of their constituents, are known to exhibit solvent properties very similar to those of ILs and have been employed for MOF synthesis. They have advantages over other types of ILs such as ease of preparation as pure phases from easily available components, low prices, and relative unreactivity towards atmospheric moisture. DES can act as both a solvent and a ligand during the MOF synthesis. MOFs can be synthesized by sonochemical method which has exhibited rapid synthesis kinetics, uniform particle morphology, and excellent phase purity in inorganic materials synthesis. The sonochemical method promotes homogeneous nucleation and reduces crystallization time considerably via the creation, growth, and collapse of an acoustic cavity, generating extremely high temperature (5000-25000 K)/pressure as well as fast heating and cooling rates. In the sonochemical synthesis route, in connection with this reaction mechanism, DESs are thought to create cavitation easily at relatively high temperatures due to their low vapor pressures, and thus have good potential as a reaction medium in the sonochemical synthesis of nanomaterials. In this work, we have chosen the widely investigated Cu3(BTC)2 as a representative MOF material for sonochemical synthesis using choline chloride/dimethylurea DES as a solvent (designated as S-CuBTC). To the best of our knowledge, this is the first report of sonochemical synthesis of a MOF structure in a DES. Effects of various synthesis parameters on the crystallization process of Cu3(BTC)2 were examined, and the properties of the sample were compared to those of Cu3(BTC)2 prepared via a conventional ionothermal synthesis route in an oven (designated as C-CuBTC). In order to use MOFs for adsorption, rigorous guest removal from the pores has to be performed so as to achieve the highest possible surface area (and pore volume). This is typically accomplished by solvent washing and vacuum treatment. Since the mixture of choline chloride and 1,3dimethylurea in a molar ratio of 1:2 used in this work has a eutectic temperature of around 70 C, removal of the solvent guest before it solidifies inside the pores is challenging. Thus, an effective activation procedure for Cu3(BTC)2 samples obtained under ionothermal synthesis conditions was briefly examined by conducting repeated sample washing with de-ionized water and ethanol in the manner described in entries I to V in Table 1. No apparent PXRD patterns or morphology changes were observed after washing step II (see Figure S1 and S2). The corresponding SEM images after different washing steps did not reveal any noticeable differences either, except that the DES coated at the external surface in the Cu3(BTC)2 sample was removed. However, repeated washing (200 mL × 2) by de-ionized water and ethanol was necessary to obtain the BET surface area of a high quality Cu3(BTC)2, as shown in Table 1. Elemental analysis of the C-CuBTC sample after washing treatment IV confirmed the virtual elimination of DES; The

Mesoporous lanthanum–manganese oxides with nanoscale periodicity, high surface area and ferromagnetic property

Designing and synthesis of inorganic materials containing magnetic elements with nanoscale periodicity is one of the areas of major research interests due to their potential memory applications. A series of ordered mesoporous lanthanum–manganese oxides has been synthesized hydrothermally using saturated fatty acids as templates in the presence of ethylenediamine (EDA) as mineralizer. Templates are removed from these as-synthesized materials through repeated ethanol–EDA extraction at 333 K. As-synthesized and template-free samples have been characterized by powder X-ray diffraction, transmission and scanning electron microscopy, N 2 sorption and X-ray photoelectron spectroscopic studies. The observed BET surface area for the template-extracted sample synthesized by using lauric acid is 304 m 2 g −1, which on further heating at 673 K resulted in a nonstoichiometric porous LaMnO 3+ δ manganite material having a further improved BET surface area of 406 m 2 g −1. The low temperature magnetic measurements revealed that the material becomes ferromagnetic at 45 K.

Fabrication of teardrop-shaped silica particles in polyelectrolyte diluted solution through in situ sol–gel process

A new strategy to fabricate teardrop-shaped silica particles is presented. Monodispersed teardrop-like silica particles were obtained through basic catalyzed sol–gel process of tetraethoxysilane by employed sodium polyacrylate as soft template. Increasing the salt concentration of solution, the morphology of silica particles can transform from teardrop-like to hollow structures, and finally formed solid particles. The morphologies of silica particles are characterized by TEM and SEM. Our finding can be scaled up for large-scale synthesis of unusual structures of inorganic or composite materials in a predictable manner. This study is expected to provide further understanding of the role of polyelectrolyte in the synthesis of inorganic materials towards design of unusual architectures and functional materials.

Light-Assisted Synthesis of Metal Oxide Heirarchical Structures and Their Catalytic Applications

Short reaction times and morphology control in the synthesis of inorganic materials under nonthermal conditions remain a challenge. Herein we report a rapid, self-templating, and nonthermal method based on ultraviolet light to prepare metal oxide hierarchical structures. With this method, the morphology of the metal oxides was controlled readily without using templates.

Transcription of pH-sensitive supramolecular assemblies into silica: from straight, coiled, and helical tubes to single and double fan-like bundles

The transcription of self-assembled organic structures by the sol–gel process is a powerful method in the synthesis of inorganic materials with controlled sizes, shapes, and porosities. Lithocholic acid (LCA) shows pH-sensitive supramolecular assemblies in aqueous solution, which can be used as tunable templates in the synthesis of silica replicas. Micro- and submicro-scale silica structures from straight, coiled, and helical tubes to single and double fan-like bundles are formed by the sol–gel transcription of pH-sensitive LCA assemblies with tetraethoxysilane (TEOS) in the presence of ammonia catalyst.

Controllable synthesis, characterization and growth mechanism of three-dimensional hierarchical PbWO4 microstructures

We report on the synthesis of three-dimensional (3D) hierarchical PbWO4 microstructures by an oil-in-water microemulsion-mediated route. As-prepared PbWO4 samples are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A possible three-step growth mechanism of PbWO4, in which initial nucleation, self-assembly (oriented aggregation), and subsequent crystal growth (Ostwald ripening) are involved, is proposed to explain the formation of PbWO4 microstructures based on observations of a time-dependent morphology evolution process. The approach is facile, environmentally friendly, and provides a new strategy in the use of microemulsion systems for material design and processing. The oil-in-water microemulsion technique presented here offers promising microstructured media for the synthesis of other inorganic materials with complex 3D architectures and unique morphologies and properties.

Materials design using genetically engineered proteins

A variety of inorganic materials with amazingly complex structures and morphologies are produced by natural organisms. The fundamental mechanism underlying the natural biological synthesis of inorganic materials can be ascribed to the unique recognition and interaction of proteins with specific inorganic species. By mimicking natural biomineralization, genetically engineered proteins have in recent years been successfully utilized as platforms for the synthesis of inorganic nanostructures of various compositions under mild reaction conditions. Moreover, the precisely oriented assembly of genetically engineered proteins offers flexibility in designing inorganic nanostructures with desired complex architecture. This short review summarizes the recent progress in materials design using genetically engineered protein templates.

Morphological Evolution of Cu2O Nanocrystals in an Acid Solution: Stability of Different Crystal Planes

The morphological evolution of uniform Cu(2)O nanocrystals with different morphologies in a weak acetic acid solution (pH = 3.5) has been studied for cubic, octahedral, rhombic dodecahedral, {100} truncated octahedral, and {110} truncated octahedral nanocrystals. Cu(2)O nanocrystals undergo oxidative dissolution in weak acid solution, but their morphological changes depend on the exposed crystal planes. We found that the stability of Cu(2)O crystal planes in weak acid solution follows the order of {100} ≫ {111} > {110} and determines how the morphology of Cu(2)O nanocrystals evolves. The stable {100} crystal planes remain, and new {100} facets form at the expense of the less stable {111} and {110} crystal planes on the surface of Cu(2)O nanocrystals. Density functional theory calculations reveal that the Cu-O bond on Cu(2)O(100) surface has the shortest bond length. These results clearly exemplify that the morphology of inorganic crystals will evolve with the change of local chemical environment, shedding light on fundamentally understanding the morphological evolution of natural minerals and providing novel insights into the geomimetic synthesis of inorganic materials in the laboratory.

Inorganic fullerene-like materials for increased operational life in rolling/sliding applications

The synthesis of inorganic fullerene-like materials (IFLMs) represents a major scientific breakthrough, and recently, new coatings and lubricants incorporating inorganic fullerene-like nanoparticles have been produced within the integrated European project FOREMOST. The objective of the work presented here was to assess the influence of IFLM in lubricants on the contact fatigue and wear performance of tribological contacts subjected to rolling/sliding motion such as gears. The wear tests were carried out using a double disc rig with specimens manufactured from S156 steel. The lubricants tested were two gear oils without IFLM and mixed with IFLM. The results show that a significant increase in the operational life of rolling/sliding components can be achieved using lubricants incorporating IFLMs.

Tunable Size and Shape Control of Platinum Nanocrystals from a Single Peptide Sequence

Nanoscale platinum architectures have been extensively studied as potential materials for applications in catalysis and fuel cells. Due to the high cost of platinum, much of the research has been geared toward developing methods to obtain monodisperse, monomorphic nanocrystals smaller than 10 nm. Peptide-mediated synthesis of inorganic materials is an attractive alternative to colloidal synthesis because it can be performed under ambient conditions and the peptides can be removed from the metal surfaces at mild pH or in the presence of enzymes. As a first step to achieve size and shape-controlled nanocrystals using peptides, we demonstrate here (a) the isolation of peptides that bind to specific crystal planes of platinum and (b) that a single peptide can produce structures ranging from sub-2 nm seed crystals to monodisperse 4 nm platinum polyhedra to 7 to 8 nm platinum cubes simply by changing the rates of metal reduction. This work demonstrates the first steps toward achieving biochemical control of platinum nanocrystal synthesis.

Biomimetic synthesis of inorganic materials and their applications

Mimicking the evolution processes of Nature, the combinatorial approach to biomolecular recognition properties attracts much attention due to the potential as a generic scheme to achieving complex material structures and hierarchical assemblies with molecular precision from the bottom up. In this paper, some recent efforts in the biomimetic synthesis of inorganic materials are reviewed, with emphasis placed on in vitro material formation with the use of protein/peptide molecules found in natural organisms as well as those with specific affinities to inorganic materials selected through the molecular evolution process. The applications of material-specific peptides and proteins in sensing and guiding hierarchical material assembly are also briefly discussed at the end.

DNA-mediated morphosynthesis of calcium carbonate particles

Calcium carbonate microspheres with different surface structures were successfully prepared by the reaction of sodium carbonate with calcium chloride in the presence of deoxyribonucleic acid (DNA) at room temperature. The as-prepared products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA-DSC) and fourier-transform infrared spectrometry (FTIR). The effects of concentration of DNA on the morphologies of the prepared CaCO(3) were investigated and discussed. The results show that the surface morphology or texture of CaCO(3) microspheres can easily be adjusted by varying the concentration of DNA. A critical implication was that DNA molecules could mediate the nucleation and growth of the inorganic phase and probably induce biomineralization in the biological system. This research may provide new insight into the control of morphologies of calcium carbonate and the biomimetic synthesis of novel inorganic materials.

Design and Synthesis of Red-Colored Inorganic Luminescent Materials

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