Polyfunctional inorganic-organic hybrid materials: an unusual kind of NLO active layered mixed metal oxalates with tunable magnetic properties and very large second harmonic generation

Mixed M(II)/M(III) metal oxalates, as "stripes" connected through strong hydrogen bonding by para-dimethylaminobenzaldeide (DAMBA) and water, form an organic-inorganic 2D network that enables segregation in layers of the cationic organic NLO-phore trans-4-(4-dimethylaminostyryl)-1-methylpyridinium, [DAMS+]. The crystalline hybrid materials obtained have the general formula [DAMS]4[M2M'(C2O4)6].2DAMBA.2H2O (M = Rh, Fe, Cr; M' = Mn, Zn), and their overall three-dimensional packing is non-centrosymmetric and polar, therefore suitable for second harmonic generation (SHG). All the compounds investigated are characterized by an exceptional SHG activity, due both to the large molecular quadratic hyperpolarizability of [DAMS+] and to the efficiency of the crystalline network which organizes [DAMS+] into head-to-tail arranged J-type aggregates. The tunability of the pairs of metal ions allows exploiting also the magnetic functionality of the materials. Examples containing antiferro-, ferro-, and ferri-magnetic interactions (mediated by oxalato bridges) are obtained by coupling proper M(III) ions (Fe, Cr, Rh) with M(II) (Mn, Zn). This shed light on the role of weak next-nearest-neighbor interactions and main nearest-neighbor couplings along "stripes" of mixed M(II)/M(III) metal oxalates of the organic-inorganic 2D network, thus suggesting that these hybrid materials may display isotropic 1D magnetic properties along the mixed M(II)/M(III) metal oxalates "stripes".     

Magnetic and mechanical anisotropy in a manganese 2-methylsuccinate framework structure

Hybrid inorganic-organic framework materials exhibit unique properties that can be advantageously tuned through choice of the inorganic and organic components and by control of the crystal structure. We present a new hydrothermally prepared 3D hybrid framework, [Mn(2-methylsuccinate)](n) (1), comprising alternating 2D manganese oxide sheets and isolated MnO(6) octahedra, pillared via syn, anti-syn carboxylates. Powder magnetic characterization shows that the compound is a homospin Mn(II) ferrimagnet below 2.4 K. The easy-axis is revealed by single-crystal magnetic susceptibility studies and a magnetic structure is proposed. Anisotropic elastic moduli and hardness, observed through nanoindentation on differing crystal facets, were correlated with specific structural features. Such measurements of anisotropy are not commonly undertaken, yet allow for a more comprehensive understanding of structure-property relationships.     

Tunable white-light emission of lanthanide(Ⅲ) hybrid material based on hectorite

In this work, we present novel trivalent lanthanide ions(Ln~(3+))-based luminescent hybrid materials, in which the organic ligands are covalently grafted on the hectorite templates and the Ln~(3+) ions can be well immobilized by the ligands through coordination bond. The hybrid materials exhibit tunable emission colors by varying the molar ratio of Eu~(3+) to Tb~(3+), and the one with Eu~(3+):Tb~(3+)=1:1 exhibits excellent coordinate of(0.327, 0.328) located in the "white region" of the CIE 1931 chromaticity diagram(under300 nm UV illumination). These properties make the hybrid composites suitable for fabricating optoelectronic devices such as full-color displays and white LED.     

Synthesis of nickel bowl-like nanoparticles and their doping for inducing planar alignment of a nematic liquid crystal

Nickel bowl-like nanoparticles have first been synthesized by a magnetic self-assembly process stabilized by polyvinyl pyrrolidone (PVP) without any sphere-like materials as templates. A trace of doped bowls can induce liquid crystal (LC) molecules into a perfect planar alignment, attributable to their bowl-like shape and magnetic self-assembly into a 1D structure. It would provide a novel method of establishing LCs alignment by doping special nanostructured materials.     

Stimuli-sensitive core/shell template particles for immobilizing inorganic nanoparticles in the core

We synthesize and characterize stimuli-sensitive core/shell particles with functional group (or material) localized in the core. We previously reported two types of hybrid particles prepared by using the template particles which were synthesized by soap-free emulsion copolymerization with N-isopropylacrylamide and glycidyl methacrylate (GMA) as monomers but by different preparation methods. GMA has advantages in immobilizing materials having several functional groups such as thiol ones. In this study, to obtain the suitable template particles for immobilizing any inorganic nanoparticles in the core, we investigated the effect of feed ratio of the two monomers. Obtained template particles were modified by thiol compounds to introduce ionic groups. They were characterized by dynamic light scattering and scanning electron microscopy. After in situ synthesis of magnetic nanoparticles in the templates, the hybrid particles were characterized directly by transmission electron microscopy. Consequently, we could obtain the hybrid core/shell particles which contained a large amount of magnetic nanoparticles (∼33 wt%) in the core.     

Reactive Template Synthesis of Polypyrrole Nanotubes for Fabricating Metal/Conducting Polymer Nanocomposites

Unique nanocomposites of polypyrrole/Au and polypyrrole/Pt hybrid nanotubes are synthesized employing polypyrrole (PPy) nanotubes as an advanced support by solution reduction. The conducting polymer PPy nanotubes are fabricated by using pre‐prepared MnO₂ nanowires as the reactive templates. MnO₂ nanowires induce the 1D polymerization of pyrrole monomers and the simultaneous dissolution of the templates affords the hollow tube‐like structure. The loading content of metal nanoparticles in the nanocomposites could be adjusted by simply changing the amount of metal precursors. This work provides an efficient approach to fabricate an important kind of metal/conducting polymer hybrid nanotubes that are potentially useful for electrocatalyst and sensor materials.     

Infinite Twisted Polycatenanes

Poly[n]catenanes have exceptional mechanical bonding properties that give them tremendous potential for use in the development of molecular machines and soft materials. Synthesizing these compounds has, however, proven to be a formidable challenge. Herein, we describe a concise method for the construction of twisted polycatenanes. Our approach involves using preorganized double helicates as templates, linked crosswise in a linear fashion by either silver ions or triple bonds. By using this approach, we successfully synthesized twisted polycatenanes with both coordination and covalent bonding employing Ag(I) ions and ethynylene units, respectively, as the linkages and leveraging the same Ag(I)-templated double helicate in both cases. Synthesis with Ag(I) ions formed a single-crystalline one-dimensional (1D) coordination poly[n]catenane, and synthesis using ethynylene units generated 1D fibers which self-assembled with solvents to form a gel. Our results confirm the potential of multi-stranded metallohelicates for creating sophisticated mechanically interlocked molecules and polymers, which could pave the way for exploration in the realms of molecular nanotopology and materials design.     

Chemical synthesis of hybrid materials based on PAni and PEDOT with polyoxometalates for electrochemical supercapacitors

Hybrid organic–inorganic materials based on conjugated polymers constitute state-of-the-art compounds with recognized technological implications. In the area of energy conversion, production and storage devices, these materials have been applied as electrodes for batteries, supercapacitors, fuel cells or solar cells, among others. Their importance relies on the wide variety of organic and inorganic counterparts that these hybrids can be made of. The properties from each part can be tailored in order to contribute to a final desired characteristic or the combined properties from both. The unique combination of useful properties found in these materials include electronic conductivity (e⁻ or h⁺), ionic transport, reversible electroactivity, electrooptical properties typical of semiconductors as well as electrochromic, pH- and composition-dependent properties, all of them to add to their polymeric nature. This is an excellent basis for the design of hybrid materials in which either of these properties or their combinations work to enhance or combine with those of a myriad inorganic phases with electronic, magnetic, photochemical, electrochemical, optical or catalytic properties. A large variety of functional hybrid materials can thus be designed and fabricated in which multifunctionality can be easily built to address specific technological needs. In this work we present our most recent results on new synthesis methodology developed for the chemical synthesis of the hybrid PAni/PMo12 and their application as electrochemical supercapacitors. We also report the synthesis of a new hybrid material of PEDOT/PMo12 synthesized for the first time by chemical methods and applied also in electrochemical supercapacitors. Initial results shows capacitance values as high as 168 F/g for the hybrid PAni/PMo12 and about 130 F/g for the hybrid PEDOT/PMo12.     

Colloidal chemical approaches to inorganic micro- and nanostructures with controlled morphologies and patterns

The controlled synthesis of inorganic micro- and nanostructures with tailored morphologies and patterns has attracted intensive interest because the properties and performances of micro- and nanostructured materials are largely dependent on the shape and structure of the primary building blocks and the way in which the building blocks are assembled or integrated. This review summarizes the recent advances on the solution-phase synthesis of inorganic micro- and nanostructures with controlled morphologies and patterns via three typical colloidal chemical routes, i.e., synthesis based on catanionic micelles, reactive templates, and colloidal crystal templates, with focus on the approaches developed in our lab. Firstly, catanionic micelles formed by mixed cationic/anionic surfactants are used as effective reaction media for the shape-controlled synthesis of inorganic nanocrystals and the solution growth of hierarchical superstructures assembled by one-dimensional (1D) nanostructures. Secondly, reactive template-directed chemical transformation strategy provides a simple and versatile route to fabricate both hollow structures and 1D nanostructures. Thirdly, colloidal crystals are employed as very effective templates for the facile solution-phase synthesis of novel inorganic structures with controlled patterns, such as three-dimensionally (3D) ordered macroporous materials and two-dimensionally (2D) patterned nanoarrays and nanonets. Finally, a brief outlook on the future development in this area is presented.     

Structural Tunability and Diversity of Two-Dimensional Lead Halide Benzenethiolate

Two-dimensional (2D) organic-inorganic hybrid materials are currently of great interest for applications in electronics and optoelectronics. Here, the synthesis and optical properties of a new type of halide-organothiolate-mixed 2D hybrid material, Pb₂X(S-C₆H₅)₃, are reported, in which X is a halide (I, Br, or Cl). Different from conventional lead-based 2D layered materials, these compounds feature unusual five-coordinated lead centers with a stereochemically active electron lone pair on the lead atoms and four-coordinated iodine atoms. The Pb₂X(S-C₆H₅)₃ materials feature an indirect bandgap, strongly emissive long-lived self-trap states, and an extremely large Stokes shift. Interestingly, the optical bandgap of the materials can be tuned through variation of the halides; however, the photoluminescence is less sensitive to the composition and is more likely dominated by lead-sulfur lattice interactions or the lead lone-pair electrons. Our results support that a halide–organothiolate mixed anion hybrid structure offers a unique platform for discovering new exciting 2D electronic materials.     

二维有机-无机杂化钙钛矿铁电材料的研究进展

铁电性通常是指电介质材料的自发极化取向随着外加电场发生变化的性能.以自发极化为核心,铁电材料表现出优异的介电响应、热释电性、压电性、电光效应和非线性光学效应等,是一类具有广阔应用前景的功能材料.近年来,二维有机-无机杂化钙钛矿化合物在铁电研究领域崭露头角,逐渐发展为铁电材料的重要组成部分.此类材料具有独特的结构兼容性与...     

基于液相法二维异质结的空间结构可控制备

The research in two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDs) and black phosphorus, has been further flourished with the recent emergence of heterostructures composed of dissimilar 2D materials. The interfacing/coupling between different constituent components in a heterostructure has given rise to interesting phenomena and useful properties. For example, depending on the type of 2D materials, the distance and the kind of bonding between them, as well as the crystalline property of the hetero-interface, the interface may provide charge traps, exciton recombination centers, or bridges for effective charge/energy transfer. It has also been found that the spatial arrangement in addition to the composition of the constituents is an important factor influencing the overall properties of the heterostructures. Although many methods, such as dry transfer and vapor-phased growth are able to yield heterostructures from pristine or highly crystalline 2D crystals with spatial control, such as vertical heterostructures and lateral heterostructures, these methods are generally not scalable, which has restricted the use of the obtained heterostructures mostly to fundamental studies. The solution-phased synthesis methods, such as solvothermal/hydrothermal synthesis, electrochemical deposition and hot-injection method, may be more suitable for mass production of functional heterostructures despite the relatively low product quality. In the past couple of years, a diverse kinds of hetero/hybrid structures of 2D materials have been prepared successfully in wet-chemical processes. However, precise control over the geometric arrangement of the constituent components has been challenging in solution. Currently, four types of heterostructures including 2D crystals grown on a larger 2D template, vertical heterostructures, lateral heterostructures, and core-shell heterostructures have been prepared in solution. For the first type, flexible 2D nanosheets such as graphene and monolayer TMDs are used as synthesis templates to support the nucleation and growth of other 2D crystals. For vertical heterostructures, relatively rigid nanoplates are used to allow continuous deposition of 2D layers of other materials to form sandwich-like structures. The formation of lateral heterostructures requires edge growth on existing 2D materials without basal deposition, and therefore other methods such as cation exchange can be used as alternative routes. The preparation of core-shell 2D heterostructures generally involves both epitaxial edge growth and basal deposition and has been realized in both metallic and semiconductor structures. In this review, these kinds of heterostructures based on 2D materials will be discussed in terms of their synthesis methods, properties and possible applications. In addition, we will discuss the challenges and possible opportunities in this research direction.     

Breakthrough and future: nanoscale controls of compositions,morphologies, and mesochannel orientations toward advanced mesoporous materials

Currently, ordered mesoporous materials prepared through the self‐assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic‐based materials, for example, transition‐metal oxides, carbons, inorganic‐organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant‐based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation‐mediated direct templating (EDIT), spray‐dried techniques, and collaboration with hard‐templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic‐scale controls of mesochannels are important for innovative applications such as molecular‐scale devices and electrodes with enhanced diffusions of guest species. © 2010 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 321–339; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900022     

Benign‐by‐Design Solventless Mechanochemical Synthesis of Three‐, Two‐, and One‐Dimensional Hybrid Perovskites

Organic–inorganic hybrid perovskites have attracted significant attention owing to their extraordinary optoelectronic properties with applications in the fields of solar energy, lighting, photodetectors, and lasers. The rational design of these hybrid materials is a key factor in the optimization of their performance in perovskite‐based devices. Herein, a mechanochemical approach is proposed as a highly efficient, simple, and reproducible method for the preparation of four types of hybrid perovskites, which were obtained in large amounts as polycrystalline powders with high purity and excellent optoelectronics properties. Two archetypal three‐dimensional (3D) perovskites (MAPbI₃ and FAPbI₃) were synthesized, together with a bidimensional (2D) perovskite (Gua₂PbI₄) and a “double‐chain” one‐dimensional (1D) perovskite (GuaPbI₃), whose structure was elucidated by X‐ray diffraction.     

Nonspherical colloidal crystals fabricated by the thermal pressing of colloidal crystal chips

Nonspherical colloids and their ordered arrays may be more attractive in applications such as photonic crystals than their spherical counterparts because of their lower symmetries, although such structures are difficult to achieve. In this letter, we describe the fabrication and characterization of colloidal crystals constructed from nonspherical polyhedrons. We fabricated such nonspherical colloidal crystals by pressing spherical polymer colloidal crystal chips at a temperature slightly lower than the glass-transition temperature (T(g)) of these polymer colloids. During this process, the polymer microspheres were distinctively transformed into polyhedrons according to their crystal structures, whereas the long-range order of the 3D lattice was essentially preserved. Because a working temperature lower than T(g) effectively prevented the colloidal crystals from fusing into films, the spherical colloidal crystals were transformed greatly under pressure, which lead to obvious change in the optical properties of colloidal crystals. Besides their special symmetry and optical properties, these nonspherical colloidal crystals can be used as templates for 2D or 3D structures of special symmetry, such as 2D nano-networks. We anticipate that this fabrication technique for nonspherical colloidal crystals can also be extended to nonspherical porous materials.     

From two-dimensional materials to heterostructures

Graphene, hexagonal boron nitride, molybdenum disulphide, and layered transition metal dichalcogenides (TMDCs) represent a class of two-dimensional (2D) atomic crystals with unique properties due to reduced dimensionality. Stacking these materials on top of each other in a controlled fashion can create heterostructures with tailored properties that offers another promising approach to design and fabricate novel electronic devices. In this report, we attempt to review this rapidly developing field of hybrid materials. We summarize the fabrication methods for different 2D materials, the layer-by-layer growth of various vertical heterostructures and their electronic properties. Particular interests are given to in-situ stack aforementioned 2D materials in controlled sequences, and the TMDCs heterostructures.     

Tunable white-light emission of lanthanide(III) hybrid material based on hectorite

Lanthanide(III) luminescent hybrid materials based on the layered hectorite have been successfully prepared, showing tunable emission colors as well as white light by varying the molar ratio between Eu³⁺ and Tb³⁺.     

Polar discontinuities and 1D interfaces in monolayered materials

Interfaces are the birthplace of a multitude of fascinating discoveries in fundamental science, and have enabled modern electronic devices, from transistors, to lasers, capacitors or solar cells. These interfaces between bulk materials are always bi-dimensional (2D) ‘surfaces’. However the advent of graphene and other 2D crystals opened up a world of possibilities, as in this case the interfaces become one-dimensional (1D) lines. Although the properties of 1D nanoribbons have been extensively discussed in the last few years, 1D interfaces within infinite 2D systems had remained mostly unexplored until very recently. These include grain boundaries in polycrystalline samples, or interfaces in hybrid 2D sheets composed by segregated domains of different materials (as for example graphene/BN hybrids, or chemically different transition metal dichalcogenides). As for their 2D counterparts, some of these 1D interfaces exhibit polar characteristics, and can give rise to fascinating new physical properties. Here, recent experimental discoveries and theoretical predictions on the polar discontinuities that arise at these 1D interfaces will be reviewed, and the perspectives of this new research topic, discussed.     

Core–Shell LiFePO4/Carbon‐Coated Reduced Graphene Oxide Hybrids for High‐Power Lithium‐Ion Battery Cathodes

Core‐shell carbon‐coated LiFePO₄ nanoparticles were hybridized with reduced graphene (rGO) for high‐power lithium‐ion battery cathodes. Spontaneous aggregation of hydrophobic graphene in aqueous solutions during the formation of composite materials was precluded by employing hydrophilic graphene oxide (GO) as starting templates. The fabrication of true nanoscale carbon‐coated LiFePO₄‐rGO (LFP/C‐rGO) hybrids were ascribed to three factors: 1) In‐situ polymerization of polypyrrole for constrained nanoparticle synthesis of LiFePO₄, 2) enhanced dispersion of conducting 2D networks endowed by colloidal stability of GO, and 3) intimate contact between active materials and rGO. The importance of conducting template dispersion was demonstrated by contrasting LFP/C‐rGO hybrids with LFP/C‐rGO composites in which agglomerated rGO solution was used as the starting templates. The fabricated hybrid cathodes showed superior rate capability and cyclability with rates from 0.1 to 60 C. This study demonstrated the synergistic combination of nanosizing with efficient conducting templates to afford facile Li⁺ ion and electron transport for high power applications.     

Preparation and characterization of 3D collagen materials with magnetic properties

In this study 3D collagen materials with magnetic properties were prepared by lyophilization technique. Magnetic particles were synthesized by precipitation of iron (II) sulfate heptahydrate and iron (III) chloride hexahydrate in an aqueous solution of chitosan and then added to a collagen solution. Starch dialdehyde (DAS) was used as a cross-linking agent for the materials. The properties of the obtained materials were studied using infrared spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, mechanical properties, porosity, density, swelling and moisture content were measured.It was found that 3D composites made from collagen with magnetic particles are hydrophilic with a high swelling ability. Cross-linking of such collagen materials with dialdehyde starch (DAS) alters the swelling degree, porosity and density of materials. The addition of magnetic particles to collagen materials decreases its porosity, and increases the density of the studied materials. Collagen 3D materials with magnetic particles are rigid and inflexible. Magnetic properties of the 3D collagen materials containing magnetic particles were confirmed by the interaction of this material with a magnet.