Superstructures of Self‐Organizing Thiophenes

The self‐assembling properties of π‐conjugated oligo‐, poly‐, and cyclothiophenes (see Figure) have been studied with different techniques. Scanning tunneling microscopy on perfectly ordered two‐dimensional monolayers at the solution–HOPG (highly oriented pyrolytic graphite) interface has successfully been applied. The submolecular resolution achieved in the STM images provides valuable lattice and molecular information. Supported by X‐ray structure analyses of the 3D bulk material and by theoretical calculations, molecular conformations, molecule–molecule, and molecule–substrate interactions of the oligo‐, poly‐, and cyclomers have been analyzed and discussed.     

Piecewise Phototuning of Self‐Organized Helical Superstructures

Cholesteric liquid crystals (CLCs) exhibit selective reflection that can be tuned owing to the dynamic control of inherent self‐organized helical superstructures. Although phototunable reflection is reported, these systems hitherto suffer from a limitation in that the tuning range is restricted to one narrow period and the optically addressed images have to sacrifice one color in the visible spectrum to serve as the background, resulting from the insufficient variation in helical twisting power of existing photoresponsive chiral switches that are all bistable. Here, delicate patterns of three primary red, green, and blue (RGB) colors with a black background are presented, which is realized based on piecewise reflection tuning of the CLC induced by a newly designed photoresponsive tristable chiral switch. Three stable configurations of the chiral switch endow the CLC with two continuous and adjacent tuning periods of the reflection, covering not only entire visible spectrum, but also one more wide period within near‐infrared region. Therefore, the concept of piecewise tuning in CLC system demonstrates a new strategy for phototunable RGB and black reflective display.     

Polymer‐Controlled Crystallization of Unique Mineral Superstructures

The origin of complex superstructures of biomaterials in biological systems and the amazing self‐assembly mechanisms of their emergence have attracted a great deal of attention recently. Mimicking nature, diverse kinds of hydrophilic polymers with different functionalities and organic insoluble matrices have been designed for the morphogenesis of inorganic crystals. In this Research News, emerging new strategies for morphogenesis and controlled crystal growth of minerals, that is, selective adsorption and mesoscale transformation for highly ordered superstructures, the combination of a synthetic hydrophilic polymer with an insoluble matrix, a substrate, or the air/solution interface, and controlled crystallization in a mixed solvent are highlighted. It is shown that these new strategies can be even further extended to morphogenesis and controlled crystallization of diverse inorganic or inorganic–organic hybrid materials with structural complexity, structural specialties, and improved functionalities.     

Architectural Design of Self‐Assembled Hollow Superstructures

Colloidal nanoparticle assemblies are widely designed and fabricated via various building blocks to enhance their intrinsic properties and potential applications. Self‐assembled hollow superstructures have been a focal point in nanotechnology for several decades and are likely to remain so for the foreseeable future. The novel properties of self‐assembled hollow superstructures stem from their effective spatial utilization. As such, a comprehensive appreciation of the interactive forces at play among individual building blocks is a prerequisite for designing and managing the self‐assembly process, toward the fabrication of optimal hollow nanoproducts. Herein, the emerging approaches to the fabrication of self‐assembled hollow superstructures, including hard‐templated, soft‐templated, self‐templated, and template‐free methods, are classified and discussed. The corresponding reinforcement mechanisms, such as strong ligand interaction strategies and extra‐capping strategies, are discussed in detail. Finally, possible future directions for the construction of multifunctional hollow superstructures with highly efficient catalytic reaction systems and an integration platform for bioapplications are discussed.     

Directing Gold Nanoparticles into Free‐Standing Honeycomb‐Like Ordered Mesoporous Superstructures

2D mesoporous materials fabricated via the assembly of nanoparticles (NPs) not only possess the unique properties of nanoscale building blocks but also manifest additional collective properties due to the interactions between NPs. In this work, reported is a facile and designable way to prepare free‐standing 2D mesoporous gold (Au) superstructures with a honeycomb‐like configuration. During the fabrication process, Au NPs with an average diameter of 5.0 nm are assembled into a superlattice film on a diethylene glycol substrate. Then, a subsequent thermal treatment at 180 °C induces NP attachment, forming the honeycomb‐like ordered mesoporous Au superstructures. Each individual NP connects with three neighboring NPs in the adjacent layer to form a tetrahedron‐based framework. Mesopores confined in the superstructure have a uniform size of 3.5 nm and are arranged in an ordered hexagonal array. The metallic bonding between Au NPs increases the structural stability of architected superstructures, allowing them to be easily transferred to various substrates. In addition, electron energy‐loss spectroscopy experiments and 3D finite‐difference time‐domain simulations reveal that electric field enhancement occurs at the confined mesopores when the superstructures are excited by light, showing their potential in nano‐plasmonic applications.     

Digitalizing Self‐Assembled Chiral Superstructures for Optical Vortex Processing

Cholesteric liquid crystal (CLC) chiral superstructures exhibit unique features; that is, polychromatic and spin‐determined phase modulation. Here, a concept for digitalized chiral superstructures is proposed, which further enables the arbitrary manipulation of reflective geometric phase and may significantly upgrade existing optical apparatus. By encoding a specifically designed binary pattern, an innovative CLC optical vortex (OV) processor is demonstrated. Up to 25 different OVs are extracted with equal efficiency over a wavelength range of 116 nm. The multiplexed OVs can be detected simultaneously without mode crosstalk or distortion, permitting a polychromatic, large‐capacity, and in situ method for parallel OV processing. Such complex but easily fabricated self‐assembled chiral superstructures exhibit versatile functionalities, and provide a satisfactory platform for OV manipulation and other cutting‐edge territories. This work is a vital step towards extending the fundamental understanding and fantastic applications of ordered soft matter.     

Antipulverization Electrode Based on Low‐Carbon Triple‐Shelled Superstructures for Lithium‐Ion Batteries

The realization of antipulverization electrode structures, especially using low‐carbon‐content anode materials, is crucial for developing high‐energy and long‐life lithium‐ion batteries (LIBs); however, this technology remains challenging. This study shows that SnO₂ triple‐shelled hollow superstructures (TSHSs) with a low carbon content (4.83%) constructed by layer‐by‐layer assembly of various nanostructure units can withstand a huge volume expansion of ≈231.8% and deliver a high reversible capacity of 1099 mAh g^?1 even after 1450 cycles. These values represent the best comprehensive performance in SnO₂‐based anodes to date. Mechanics simulations and in situ transmission electron microscopy suggest that the TSHSs enable a self‐synergistic structure‐preservation behavior upon lithiation/delithiation, protecting the superstructures from collapse and guaranteeing the electrode structural integrity during long‐term cycling. Specifically, the outer shells during lithiation processes are fully lithiated, preventing the overlithiation and the collapse of the inner shells; in turn, in delithiation processes, the underlithiated inner shells work as robust cores to support the huge volume contraction of the outer shells; meanwhile, the middle shells with abundant pores offer sufficient space to accommodate the volume change from the outer shell during both lithiation and delithiation. This study opens a new avenue in the development of high‐performance LIBs for practical energy applications.     

Large‐Area 3D Hierarchical Superstructures Assembled from Colloidal Nanoparticles

Assembling nanosized building blocks into macroscopic 3D complex structures is challenging. Here, nanosized metal and semiconductor building blocks with a variety of sizes and shapes (spheres, stars, and rods) are successfully assembled into a broad range of hierarchical (nanometer to micrometer) assemblies of functional materials in centimeter size using butterfly wings as templates. This is achieved by the introduction of steric hindrance to the assembly process, which compensates for attraction from the environmentally sensitive hydrogen bonds and prevents the aggregation of nanosized building blocks. Of these materials, Au nanostar assemblies show a superior enhancement in surface‐enhanced Raman scattering (SERS) performance (rhodamine 6G, 1506 cm^?1) under 532, 633, and 780 nm excitation—this is 3.1–4.4, 3.6–3.9, and 2.9–47.3 folds surpassing Au nanosphere assemblies and commercial SERS substrates (Q‐SERS), respectively. This method provides a versatile route for the assembly of various nanosized building blocks into different 3D superstructures and for the construction of hybrid nanomaterials and nanocomposites.     

DNA‐Assembled Core‐Satellite Upconverting‐Metal–Organic Framework Nanoparticle Superstructures for Efficient Photodynamic Therapy

DNA‐mediated assembly of core–satellite structures composed of Zr(IV)‐based porphyrinic metal‐organic framework (MOF) and NaYF₄,Yb,Er upconverting nanoparticles (UCNPs) for photodynamic therapy (PDT) is reported. MOF NPs generate singlet oxygen (¹O₂) upon photoirradiation with visible light without the need for additional small molecule, diffusional photosensitizers such as porphyrins. Using DNA as a templating agent, well‐defined MOF–UCNP clusters are produced where UCNPs are spatially organized around a centrally located MOF NP. Under NIR irradiation, visible light emitted from the UCNPs is absorbed by the core MOF NP to produce ¹O₂ at significantly greater amounts than what can be produced from simply mixing UCNPs and MOF NPs. The MOF–UCNP core–satellite superstructures also induce strong cell cytotoxicity against cancer cells, which are further enhanced by attaching epidermal growth factor receptor targeting affibodies to the PDT clusters, highlighting their promise as theranostic photodynamic agents.     

Stimuli‐Driven Control of the Helical Axis of Self‐Organized Soft Helical Superstructures

Supramolecular and macromolecular functional helical superstructures are ubiquitous in nature and display an impressive catalog of intriguing and elegant properties and performances. In materials science, self‐organized soft helical superstructures, i.e., cholesteric liquid crystals (CLCs), serve as model systems toward the understanding of morphology‐ and orientation‐dependent properties of supramolecular dynamic helical architectures and their potential for technological applications. Moreover, most of the fascinating device applications of CLCs are primarily determined by different orientations of the helical axis. Here, the control of the helical axis orientation of CLCs and its dynamic switching in two and three dimensions using different external stimuli are summarized. Electric‐field‐, magnetic‐field‐, and light‐irradiation‐driven orientation control and reorientation of the helical axis of CLCs are described and highlighted. Different techniques and strategies developed to achieve a uniform lying helix structure are explored. Helical axis control in recently developed heliconical cholesteric systems is examined. The control of the helical axis orientation in spherical geometries such as microdroplets and microshells fabricated from these enticing photonic fluids is also explored. Future challenges and opportunities in this exciting area involving anisotropic chiral liquids are then discussed.     

Mesocrystals—Ordered Nanoparticle Superstructures

Mesocrystals are 3D ordered nanoparticle superstructures, often with internal porosity, which receive much recent research interest. While more and more mesocrystal systems are found in biomineralization or synthesized, their potential as material still needs to be explored. It needs to be revealed, which new chemical and physical properties arise from the mesocrystal structure, or how they change by the ordered aggregation of nanoparticles to fully exploit the promising potential of mesocrystals. Also, the mechanisms for mesocrystal synthesis need to be explored to adapt it to a wide class of materials. The last three years have seen remarkable progress, which is summarized here. Also potential future directions of this reaserch field are discussed. This shows the importance of mesocrystals not only for the field of materials research and allows the appliction of mesocrystals in advanced materials synthesis or property improvement of existing materials. It also outlines attractive research directions in this field.     

Colloid‐Interface‐Assisted Laser Irradiation of Nanocrystals Superlattices to be Scalable Plasmonic Superstructures with Novel Activities

High‐efficient charge and energy transfer between nanocrystals (NCs) in a bottom‐up assembly are hard to achieve, resulting in an obstacle in application. Instead of the ligands exchange strategies, the advantage of a continuous laser is taken with optimal wavelength and power to irradiate the film‐scale NCs superlattices at solid–liquid interfaces. Owing to the Au‐based NCs' surface plasmon resonance (SPR) effect, the gentle laser irradiation leads the Au NCs or Au@CdS core/shell NCs to attach each other with controlled pattern at the interfaces between solid NCs phase and liquid ethanol/ethylene glycol. A continuous wave 532 nm laser (6.68–13.37 W cm^?2), to control Au‐based superlattices, is used to form the monolayer with uniformly reduced interparticle distance followed by welded superstructures. Considering the size effect to Au NCs' melting, when decreasing the Au NCs size to ≈5 nm, stronger welding nanostructures are obtained with diverse unprecedented shapes which cannot be achieved by normal colloidal synthesis. With the help of facile scale‐up and formation at solid–liquid interfaces, and a good connection of crystalline between NCs, the obtained plasmonic superstructured films that could be facilely transferred onto different substrates exhibit broad SPR absorption in the visible and near‐infrared regime, enhanced electric conductivities, and wide applications as surface enhanced Raman scattering (SERS)‐active substrates.     

Crystal Phase and Architecture Engineering of Lotus‐Thalamus‐Shaped Pt‐Ni Anisotropic Superstructures for Highly Efficient Electrochemical Hydrogen Evolution

The rational design and synthesis of anisotropic 3D nanostructures with specific composition, morphology, surface structure, and crystal phase is of significant importance for their diverse applications. Here, the synthesis of well‐crystalline lotus‐thalamus‐shaped Pt‐Ni anisotropic superstructures (ASs) via a facile one‐pot solvothermal method is reported. The Pt‐Ni ASs with Pt‐rich surface are composed of one Ni‐rich “core” with face‐centered cubic (fcc) phase, Ni‐rich “arms” with hexagonal close‐packed phase protruding from the core, and facet‐selectively grown Pt‐rich “lotus seeds” with fcc phase on the end surfaces of the “arms.” Impressively, these unique Pt‐Ni ASs exhibit superior electrocatalytic activity and stability toward the hydrogen evolution reaction under alkaline conditions compared to commercial Pt/C and previously reported electrocatalysts. The obtained overpotential is as low as 27.7 mV at current density of 10 mA cm^?2, and the turnover frequency reaches 18.63 H₂ s^?1 at the overpotential of 50 mV. This work provides a new strategy for the synthesis of highly anisotropic superstructures with a spatial heterogeneity to boost their promising application in catalytic reactions.