从纳米晶到三维超晶格结构

纳米晶的有序组装对未来纳米材料的应用拓展具有重要意义. 本综述介绍了纳米晶三维超晶格的研究价值以及制备方法,着重对“胶体溶液蒸发”、“不良溶剂扩散”、“胶束引导集聚”、“氢键连接”、“静电聚集”、“DNA导向”、“外场辅助”和“水－油界面辅助”的组装机制进行了总结与评述,同时也探讨了这一新兴领域中仍然存在的挑战.     

Synthesis of self-assembled 3D flowerlike SnS2 nanostructures with enhanced lithium ion storage property

In this work, we reported a facile ethanol solvothermal approach to fabricate highly dispersive 3D flowerlike SnS₂ architectures. The effects of synthetic conditions, such as the solvent system and the concentration of thiourea, on the morphology of the products were investigated. A possible growth mechanism for the formation of 3D flowerlike architectures was preliminarily propounded on the basis of the evolution of the structure and the morphology with increasing the reaction time. As anode materials of rechargeable Li-ion batteries, the as-prepared flowerlike SnS₂ structures exhibited exceptional good electrochemical properties, which revealed a higher reversible capacity about 502 mA h g^?1 and more stable cyclic retention at 50th cycle than the as-prepared SnS₂ nanoplates. The reasons for the improved electrochemical performance of the flowerlike structures have been proposed. All the results demonstrated that they were potential anode materials in Li-ion batteries.     

Self-assembly of lanthanide helicate coordination polymers into 3D metal-organic framework structures

Pyridine-2,6-dicarboxylic acid (pdcH(2) ) reacts with nitrate salts of La(III), Ce(III), and Nd(III) under hydrothermal conditions to form three-dimensional network structures, 1-4. All the compounds crystallize in the monoclinic space group P2(1)/c with the following lattice parameters: [La(2)(pdc)(3).3H(2)O] 1, a = 10.966(3) A, b = 17.534(4) A, c = 13.578(2) A, beta = 100.23(3) degrees, V( )()= 2569.3(9) A(3), Z = 4, R1 = 0.052, wR2 = 0.143, S = 1.06; [Ce(2)(pdc)(3).3H(2)O] 2, a = 12.701(3) A, b = 9.979(1) A, c = 19.401(4) A, beta = 97.73(2) degrees, V( )()= 2436.6(8) A(3), Z = 4, R1 = 0.039, wR2 = 0.117, S = 1.30; [Ce(2)(pdc)(3).3H(2)O] 3, a = 10.961(5) A, b = 17.523(5) A, c = 13.505(2) A, beta = 100.89(3) degrees, V( )()= 2547.2(8) A(3), Z = 4, R1 = 0.040, wR2 = 0.103, S = 1.08; [Nd(2)(pdc)(3).3H(2)O] 4, a = 10.944(3) A, b = 17.448(5) A, c = 13.397(2) A, beta = 101.19(3) degrees, V( )()= 2569.3(9) A(3), Z = 4, R1 = 0.052, wR2 = 0.143, S = 1.06. Compounds 1, 3, and 4 form infinite single helical chains with large widths and pitches containing four metal ions per turn while 2 forms a different helix with smaller width and pitch containing two metal ions per turn. Each helix is further bonded on either side via carboxylate bridging producing three-dimensional metal-organic framework structures.     

A high activity photocatalyst of hierarchical 3D flowerlike ZnO microspheres: synthesis, characterization and catalytic activity

This contribution reports the design, preparation, and characterization of nanostructured hybrid films of silver nanoparticles (AgNPs) and a tailored nitric oxide (NO) photodonor. They were achieved by exploiting effective interfacial interactions between an amino-terminated NO photodonor spread onto water surface and naked AgNPs dissolved in the water subphase. The morphology, the spectroscopic features, and the interaction between the two components in the floating films at the air/water interface were inspected by Brewster Angle Microscopy, UV-Vis reflection, and polarization-modulation infrared reflection-absorption spectroscopy. AgNPs and the NO photodonor were successfully transferred onto hydrophobized quartz substrates by horizontal lifting deposition and the resulting multilayer films were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy, respectively. The results obtained showed the presence of both isolated AgNPs and assemblies of AgNPs having nanodimensional character in the films. The photochemical properties of the NO photodonor were well preserved in the hybrid multilayers. In fact, they were able to release NO under visible light excitation, as unambiguously demonstrated by the direct and in real-time monitoring of this transient species using an ultrasensitive electrode, and the transfer of the released NO to a protein such as myoglobin.     

Self-assembly of ordered 3D Pd nanospheres at a liquid/liquid interface

A novel route for the self-assembly of nanoparticles to nanospheres at a liquid/liquid interface has been developed to prepare palladium nanospheres. It has proved that the interface offers an excellent site and plays a key role in the self-assembly of nanoparticles to nanospheres. The palladium nanospheres are characterized by electron microscopy, energy-dispersive X-ray analysis, UV-visible spectroscopy, X-ray diffraction spectroscopy, and X-ray photoelectron spectroscopy. The mechanism of the self-assembly process is also proposed.     

Self-assembly of unprecedented [8+12] Cu-metallamacrocycle-based 3D metal-organic frameworks

[8+12]-metallamacrocycle-based 3D frameworks {[Cu(4)(pbt)(2)(SO(4))(2)(DMF)(2)(CH(3)OH)]·7H(2)O·DMF}(n) (1) and [12]-macrocycle 3D {[Cu(2)(pbt)(SO(4))(DMSO)(CH(3)OH)(2)]·5H(2)O·CH(3)OH}(n) (2) have been obtained. Both complexes display antiferromagnetic couplings and high catalytic activity in the oxidative coupling reaction of 1-ethynylbenzene and oxazolidin-2-one.     

Constructing 3D interweaved MXene/graphitic carbon nitride nanosheets/graphene nanoarchitectures for promoted electrocatalytic hydrogen evolution

The technique of electrocatalytic hydrogen evolution reaction (HER) represents a development trend of clean energy generation and conversion,while the electrode catalysts are bound to be the core unit in the electrochemical HER system.Herein,we demonstrate a bottom-up approach to the construction of three-dimensional (3D) interconnected ternary nanoarchitecture originated from Ti₃C₂T_xMXene,graphitic carbon nitride nanosheets and graphene (MX/CN/RGO) through a con...     

Self-assembled 3D flowerlike hierarchical Fe3O4@Bi2O3 core-shell architectures and their enhanced photocatalytic activity under visible light

Three‐dimensional (3D) flowerlike hierarchical Fe₃O₄@Bi₂O₃ core–shell architectures were synthesized by a simple and direct solvothermal route without any linker shell. The results indicated that the size of the 3D flowerlike hierarchical microspheres was about 420 nm and the shell was composed of several nanosheets with a thickness of 4–10 nm and a width of 100–140 nm. The saturation magnetization of the superparamagnetic composite microspheres was about 41 emu g^?1 at room temperature. Moreover, the Fe₃O₄@Bi₂O₃ composite microspheres showed much higher (7–10 times) photocatalytic activity than commercial Bi₂O₃ particles under visible‐light irradiation. The possible formation mechanism was proposed for Ostwald ripening and the self‐assembled process. This novel composite material may have potential applications in water treatment, degradation of dye pollutants, and environmental cleaning, for example.     

Facile synthesis of 3D flowerlike CeO2 microspheres under mild condition with high catalytic performance for CO oxidation

Three-dimensional (3D) hierarchical flowerlike CeO(2) microspheres with 5-8μm diameter were hydrothermally synthesized by using multiple surfactants at very mild condition (100°C) and characterized by XRD, low-temperature N(2) adsorption, SEM, TEM, TG, FT-IR, and UV-vis spectroscopies. The results show that the flowerlike ceria prepared with the co-surfactant of sodium dodecyl sulfonic and PEG 600 possesses multilevel pore structure and low band gap energy. A possible formation mechanism of flowerlike ceria is that 3D flowerlike microspheres are assembled by 1D nanowires formed through an aggregation of 0D nanoparticles. Based on the unique structure and morphology, the prepared flowerlike CeO(2) exhibits more amount of surface capping oxygen, higher concentrations of Ce(3+) and O vacancy, and more (100) lattice planes, resulting in its higher catalytic activity for CO oxidation than general bulk ceria. Furthermore, photoluminescence property testing shows that flowerlike CeO(2) exhibits the violet blue light emission with a blue shift, because of the quantum size effect, differing from general ceria.     

界面聚合自组装合成三维多孔网络状聚邻甲基苯胺

采用界面聚合法在植酸的辅助作用下自组装合成具有连续三维多孔网络结构的聚邻甲基苯胺(POT)。采用扫描电镜(SEM)、氮气吸附和接触角测定的手段,研究了POT的微观结构、比表面积和亲水性。结果表明:当植酸浓度为0.3mol/L,聚合温度为10℃时,POT呈现三维多孔网络状形貌,开孔尺寸为0.2~1μm,且网络上附着粒径不足200nm的聚合物颗粒。该POT具有相对较高的电导率(7.52×10-3 S/cm)和比表面积(37.5 m2/g)以及较好的亲水性(接触角为34°)。在聚合过程中,多官能团的植酸既是掺杂剂又是交联剂,其与聚合物链的相互作用是该自组装行为的驱动力。     

Self-assembly of Quasi-monocrystal CdCO3 Nanorings

Hierarchical CdCO3 nanostructures with complex morphologies, such as tetrago- nal, pentagonal and hexagonal nanorings, can be prepared via self-assembly of nanocrystals in a solvothermal environment. XRD pattern indicated that the product is trigonal CdCO3 phase (PDF#850989) with cell constants a = 6.112  and α = 47.4o. Based on our experimental results, a possible nanoring formation mechanism was proposed.     

Self-assembly hexanuclear metallacontainer hosting halogenated guest species and sustaining structure of 3D coordination framework

Chloride-centered hexanuclear hydroxopyrazolate reveals potential as a receptor of halomethane and halometallate species and as a molecular building block for coordination polymers.     

Optical Transmittance of AlOOH/Al2O3 Porous Gel Preforms

Monolithic boehmite gel discs (1.2 cm) of 0.12 and 0.25 mm thickness were examined by DTA, TGA, measurements of surface area, pore volume, pore radius and on-line measurements of optical transmittance from room temperature (RT) to 1200°C. The optical transmittance reflects the water liberation out of sample discs and provides information on processes associated with the phase/microstructure changes taking place such as the crystallization of the -alumina grains.     

Rational design of DNA nanoarchitectures

DNA has many physical and chemical properties that make it a powerful material for molecular constructions at the nanometer length scale. In particular, its ability to form duplexes and other secondary structures through predictable nucleotide-sequence-directed hybridization allows for the design of programmable structural motifs which can self-assemble to form large supramolecular arrays, scaffolds, and even mechanical and logical nanodevices. Despite the large variety of structural motifs used as building blocks in the programmed assembly of supramolecular DNA nanoarchitectures, the various modules share underlying principles in terms of the design of their hierarchical configuration and the implemented nucleotide sequences. This Review is intended to provide an overview of this fascinating and rapidly growing field of research from the structural design point of view.     

Metal ions Directed Self-assembly based on Mixed Ligands: From 2D hcb Net to 3D cds Framework

Two coordination polymers (CPs), namely, [Zn(BPDC)(3-bpdb)_0.5(H₂O)₂]_n ( 1 ), and [Ni(BPDC)(3-bpdb)(H₂O)₂]_n ( 2 ) (where H₂BPDC = 4,4'-biphenyldicarboxylic acid, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene) have been solvothermally synthesized and characterized by single-crystal X-ray diffraction, IR, elemental analyses, PXRD, and SEM. CP 1 possesses a 2D 3-connected hcb net, and weak hydrogen bonding and π ··· π stacking contacts further link the 2D networks to form 3D supramolecular structure. The structure of 2 presents a 4-connected threefold interpenetrated cds framework. Through structural analysis, it is found that the coordination geometry of metal ions significantly affects the binding behaviors of the ligands and the resultant extended networks of the CPs. Besides, the Hirshfeld surface analyses detailed the surface characteristics of the two CPs. In addition, the thermal stabilities and photoluminescent properties were also investigated.     

Templateless, surfactantless, simple electrochemical route to rapid synthesis of diameter-controlled 3D flowerlike gold microstructure with "clean" surface

We report for the first time a simple low-cost electrochemical route to synthesis of diameter-controlled hierarchical flowerlike gold microstructures with "clean" surfaces using gold nanoplates or nanopricks as building blocks without introducing any template or surfactant.     

Self-assembly of aromatic sulfonamide-amide hybridized molecules: formation of 2D layers and 3D microporous networks in the solid state

Three sulfonamide-amide hybridized molecules and one cyclic analogue were synthesized and their assembling behaviors in the solid state were investigated by X-ray crystallography. The results showed that the hybridized molecules could be not only induced to take up helical secondary structures by a network of intramolecular hydrogen bonds, but also utilized as useful building blocks for assembling into 1D zigzag chains and superhelices, 2D layers and further 3D networks. Moreover, it was found that the multiple C-H?OS hydrogen bonds played an important role in the assembling processes.     

A comparison of the role of boehmite (AlOOH) and alumina (Al2O3) in the thermal stability and flammability of poly(methyl methacrylate)

In this paper, a comparison of the role of boehmite (AlOOH) and alumina (Al₂O₃) in the thermal stability and flame retardant behaviour of poly(methyl methacrylate) (PMMA) is presented. PMMA–AlOOH and PMMA–Al₂O₃ nanocomposites were prepared by melt blending with different filler contents. These nanocomposites were studied by thermogravimetric analysis (TGA) and cone calorimetry. In the presence of the filler (alumina or boehmite), the thermal stability of the polymer appeared to be significantly improved. An increase of the decomposition temperature of between about 19 and 35 °C was demonstrated by TGA. Cone calorimeter measurements showed that the peak of heat release rate is lowered in the presence of AlOOH or Al₂O₃ in comparison to pure PMMA and that this decrease is higher when the filler content increases. When loading rate is higher (15 wt%), a significant improvement in fire resistance of PMMA was observed in both systems but with two different modes of action.