Self-assembled Superstructures Research Articles

In situ coherent x-ray scattering reveals polycrystalline structure and discrete annealing events in strongly coupled nanocrystal superlattices

Solution-phase bottom up self-assembly of nanocrystals into superstructures such as ordered superlattices is an attractive strategy to generate functional materials of increasing complexity, including very recent advances that incorporate strong interparticle electronic coupling. While the self-assembly kinetics in these systems have been elucidated and related to the product characteristics, the weak interparticle bonding interactions suggest the superstructures formed could continue to order within the solution long after the primary nucleation and growth have occurred, even though the mechanism of annealing remains to be elucidated. Here, we use a combination of Bragg coherent diffractive imaging and x-ray photon correlation spectroscopy to create real-space maps of supercrystalline order along with a real-time view of the strain fluctuations in aging strongly coupled nanocrystal superlattices while they remain suspended and immobilized in solution. By combining the results, we deduce that the self-assembled superstructures are polycrystalline, initially comprising multiple nucleation sites, and that shear avalanches at grain boundaries continue to increase crystallinity long after growth has substantially slowed. This multimodal approach should be generalizable to characterize a breadth of materials in their native chemical environments, thus extending the reach of high-resolution coherent x-ray characterization to the benefit of a much wider range of physical systems. Published by the American Physical Society 2024

Exchanging and Releasing Information in Synthetic Digital Polymers Using a Strand-Displacement Strategy.

Toehold-mediated strand displacement (TMSD) was tested as a tool to edit information in synthetic digital polymers. Uniform DNA-polymer biohybrid macromolecules were first synthesized by automated phosphoramidite chemistry and characterized by HPLC, mass spectrometry, and polyacrylamide gel electrophoresis (PAGE). These precursors were diblock structures containing a synthetic poly(phosphodiester) (PPDE) segment covalently attached to a single-stranded DNA sequence. Three types of biohybrids were prepared herein: a substrate containing an accessible toehold as well as input and output macromolecules. The substrate and the input macromolecules contained noncoded PPDE homopolymers, whereas the output macromolecule contained a digitally encoded segment. After hybridization of the substrate with the output, incubation in the presence of the input led to efficient TMSD and the release of the digital segment. TMSD can therefore be used to erase or rewrite information in self-assembled biohybrid superstructures. Furthermore, it was found in this work that the conjugation of DNA single strands to synthetic segments of chosen lengths greatly facilitates the characterization and PAGE visualization of the TMSD process.

Pure-red electroluminescence of quantum-confined CsPbI3 perovskite nanocrystals obtained by the gradient purification method

Pure-red emission light-emitting diodes (LEDs) are highly desirable for display and lighting applications. Here, we present a synergistic approach to fabricate pure-red emission LEDs based on quantum-confined CsPbI3 nanocrystals (NCs). By introducing ZnI2 acting as a co-precursor and passivating agent into the synthesis, and applying a gradient post-synthesis purification method allowing us to obtain size-selected fractions with precisely adjusted emission colors, we obtained uniform and small (about 6 nm), quantum-confined CsPbI3 NCs exhibiting high stability in ambient conditions and a superior photoluminescence quantum yield of up to 88%. These NCs exhibited the tendency to undergo oriented attachment, resulting in self-assembled superstructures with a pure-red emission at 629 nm. Importantly, partial recrystallization into fused superstructures led to removal of the insulating ligand barriers between NCs. LEDs based on the CsPbI3 NCs showed pure-red electroluminescence at 633 nm, with an external quantum efficiency of 14.7% and a luminance of over 1000 cd/m2. Our study reveals the mechanism behind the oriented attachment and assembly of small, quantum-confined CsPbI3 NCs, and contributes to the development of pure-red electroluminescent LEDs.

Logical rotation of non-separable states via uniformly self-assembled chiral superstructures

The next generation of high-capacity, multi-task optical informatics requires sophisticated manipulation of multiple degrees of freedom (DoFs) of light, especially when they are coupled in a non-separable way. Vector beam, as a typical non-separable state between the spin and orbital angular momentum DoFs, mathematically akin to entangled qubits, has inspired multifarious theories and applications in both quantum and classical regimes. Although qubit rotation is a vital and ubiquitous operation in quantum informatics, its classical analogue is rarely studied. Here, we demonstrate the logical rotation of vectorial non-separable states via the uniform self-assembled chiral superstructures, with favorable controllability, high compactness and exemption from formidable alignment. Photonic band engineering of such 1D chiral photonic crystal renders the incident-angle-dependent evolution of the spatially-variant polarizations. The logical rotation angle of a non-separable state can be tuned in a wide range over 4π by this single homogeneous device, flexibly providing a set of distinguished logic gates. Potential applications, including angular motion tracking and proof-of-principle logic network, are demonstrated by specific configuration. This work brings important insight into soft matter photonics and present an elegant strategy to harness high-dimensional photonic states.

Electrostatic-Driven Self-Assembly of Janus-like Monolayer-Protected Metal Nanoclusters.

The generation of controlled microstructures of functionalized nanoparticles has been a crucial challenge in nanoscience and nanotechnology. Efforts have been made to tune ligand charge states that can affect the aggregation propensity and modulate the self-assembled structures. In this work, we modeled zwitterionic Janus-like monolayer ligand-protected metal nanoclusters (J-MPCs) and studied their self-assembly using atomistic molecular dynamics and on-the-fly probability-based enhanced sampling simulations. The oppositely charged ligand functionalization on two hemispheres of a J-MPC elicits asymmetric solvation, primarily driven by distinctive hydrogen bonding patterns in the ligand-solvent interactions. Electrostatic interactions between the oppositely charged residues in J-MPCs guide the formation of one-dimensional and ring-like self-assembled superstructures with molecular dipoles oriented in specific patterns. The pertinent atomistic insights into the intermolecular interactions governing the self-assembled structures of zwitterionic J-MPCs obtained from this work can be used to design a general strategy to create tunable microstructures of charged MPCs.

Colloidal self-assembly in biosensing strategies for biomarkers diagnosis

<p>Rapid and high-throughput detection of biomarkers plays an important role in disease diagnosis, prognosis, and monitoring treatment. Existing diagnostic tools that rely on genetic testing and antibody recognition can provide the required sensitivity and specificity. However, these methods need multiple labeling steps for the signal amplification, which are tedious and time-consuming. To address these issues, self-assembled colloidal superstructures, especially for the nanophotonic structures, exhibit many optical sensing properties in response to external stimuli, which lays the foundation for developing the next-generation biosensors. Herein, we discuss the potential of self-assembled nanophotonic-based biosensors for achieving low-cost, high-sensitive, multiplexed detection of various biomarkers, including nucleic acids, proteins, and exosomes. We conclude the current challenges in optical colloidal biosensors and offer insights into their further advances towards the smart healthcare.</p>

Self-assembled superstructures derived from suitably substituted phenanthro[9,10-d] imidazole-based Zn(ii)/Cd(ii) complexes for selective detection of acetone

Newly synthesized (L1)2M, (L2)2M, and (L3)2M (M = Zn(ii)/Cd(ii)) self-assembled into well-ordered superstructures and exhibited promising potential for developing a new class of sensor devices for human health monitoring and environmental safety measurements.

Temperature Self-Adaptive and Color-Adjustable Smart Window Based on Templated Cholesteric Liquid Crystals.

Cholesteric liquid crystals (CLCs) exhibit selective reflection due to their self-assembled helical superstructures. Reconfigurable templates can achieve integration functions via inducing processes of molecular assemblies. Here we demonstrate temperature self-adaptive and color-adjustable smart windows using CLCs, which are fabricated via the templating method and exhibit simultaneous reflections in the visible and infrared spectra. Reflection bands formed by the refilled CLC materials can be adjusted reversibly both upon thermal and electrical actuation. In CLC with adjustable reflection in the infrared, the central wavelength of the infrared reflection band can be adjusted from 950 nm to 1305 nm via temperature, and from 1150 nm to 950 nm via electric field. A temperature variation of 10.3 °C within 55 s was induced by the single-layer templated CLC cell, and a comfortable temperature range could be effectively maintained by the CLC cell in a varied environment. In CLC with dynamic color in the visible spectrum, color shifts from 530 nm to 650 nm tuned by temperature and from 530 nm to 440 nm adjusted by electric field were obtained. Temperature-responsive reflection in the infrared spectrum contributes to automatic thermal management, and electric-field-induced band shift in the visible spectrum enables active dynamic color adjustment. The presented templated CLC smart windows show considerable potential in energy conservation and biological clock regulation fields.

Non-Metallic NH4 + /H+ Co-Storage in Organic Superstructures for Ultra-Fast and Long-Life Zinc-Organic Batteries.

Compared with Zn2+ storage, non-metallic charge carrier with small hydrated size and light weight shows fast dehydration and diffusion kinetics for Zn-organic batteries. Here we first report NH4 + /H+ co-storage in self-assembled organic superstructures (OSs) by intermolecular interactions of p-benzoquinone (BQ) and 2, 6-diaminoanthraquinone (DQ) polymer through H-bonding and π-π stacking. BQ-DQ OSs exhibit exposed quadruple-active carbonyl motifs and super electron delocalization routes, which are redox-exclusively coupled with high-kinetics NH4 + /H+ but exclude sluggish and rigid Zn2+ ions. A unique 4e- NH4 + /H+ co-coordination mechanism is unravelled, giving BQ-DQ cathode high capacity (299 mAh g-1 at 1 A g-1 ), large-current tolerance (100 A g-1 ) and ultralong life (50,000 cycles). This strategy further boosts the capacity to 358 mAh g-1 by modulating redox-active building units, giving new insights into ultra-fast and stable NH4 + /H+ storage in organic materials for better Zn batteries.

Seeing the Supracolloidal Assemblies in 3D: Unraveling High-Resolution Structures Using Electron Tomography.

Transmission electron microscopy (TEM) imaging has revolutionized modern materials science, nanotechnology, and structural biology. Its ability to provide information about materials' structure, composition, and properties at atomic-level resolution has enabled groundbreaking discoveries and the development of innovative materials with precision and accuracy. Electron tomography, single particle reconstruction, and microcrystal electron diffraction techniques have paved the way for the three-dimensional (3D) reconstruction of biological samples, synthetic materials, and hybrid nanostructures at near atomic-level resolution. TEM tomography using a series of two-dimensional (2D) projections has been used extensively in biological science, but in recent years it has become an important method in synthetic nanomaterials and soft matter research. TEM tomography offers unprecedented morphological details of 3D objects, internal structures, packing patterns, growth mechanisms, and self-assembly pathways of self-assembled colloidal systems. It complements other analytical tools, including small-angle X-ray scattering, and provides valuable data for computational simulations for predictive design and reverse engineering of nanomaterials with the desired structure and properties. In this perspective, I will discuss the importance of TEM tomography in the structural understanding and engineering of self-assembled nanostructures with specific emphasis on colloidal capsids, composite cages, biohybrid superlattices with complex geometries, polymer assemblies, and self-assembled protein-based superstructures.

Construction of Quasi-Ordered Metal-Organic Frameworks Superstructures via Colloidal Assembly of Anisotropic Particles for Selective Organic Vapor Sensing.

Colloidal assembly of anisotropic particles holds great promise for achieving diverse packing geometries and unique photonic properties. One intriguing candidate for anisotropic self-assembly is colloidal metal-organic frameworks (MOFs), which possess remarkable characteristics including substantial surface areas, tunable chemical properties, a wide range of structural variations, and diverse polyhedral shapes. In this study, the colloidal assembly of nearly spherical and polyhedral MOFs particles to form quasi-ordered photonic superstructures was investigated. Specifically, monodisperse near-spherical ZIF-8 (NSZIF-8) and rhombic dodecahedron ZIF-8 (RDZIF-8) colloidal nanoparticles were synthesized as the fundamental building blocks. These nanoparticles are employed to construct MOFs-based self-assembled superstructures that exhibit thin-film interference optical properties. Importantly, these superstructures demonstrate exceptional responsiveness to gaseous homologues and isomers with approximate refractive indices. The dynamic reflection spectral patterns exhibited by these superstructures provide valuable insights into the diffusion rates and surface tension characteristics of the target solvents. These findings underscore the potential of MOFs-based superstructure thin films to discriminate between physiochemically similar solvents, opening new avenues for applications in various fields.

Controlled assembly of NiCo-LDH nanosheets into diverse superstructures via concentration-dependent solvothermal method for advanced supercapacitors

The tunable layer structure, composition, and diverse morphologies of layered double hydroxides (LDHs) make them a favorable choice as pseudocapacitive electrode materials for supercapacitors. However, the severe agglomeration and low conductivity of nanosheets are detrimental to obtaining excellent electrochemical performance. In this work, a controllable assembly of nanosheets was achieved by adjusting the concentrations of Ni and Co salt solutions, resulting in a series of 3D-shaped NiCo-LDHs superstructures with diverse morphologies. The prepared structures were found to significantly reduce aggregation and electron transport distance. The results approved that the diameter, thickness and interlayer space of NiCo-LDHs nanosheets and the morphologies of their self-assembled superstructures were subtly controlled, and significantly impacted their electrochemical performance. A stretch trumpet shaped flower-like superstructure in NiCo-LDH-2 was constructed by the large and ultrathin nanosheets with much more accessible active sites and larger interlayer space, which can rapidly promote electron transfer and show the highest specific capacitance of 2265 F g−1 at 1 A g−1 and retention of 86.5% at 20 A g−1. The NiCo-LDHs//AC ASC based on NiCo-LDH-2 and active carbon (AC) reveals a high specific capacitance of 298 F g−1 at 1 A g−1 and an excellent energy density of 105.0 Wh kg−1 at the power density of 820.1 W kg−1. The current work presents a simple way for controlling the nanostructure of NiCo-LDHs in the development of high-performance supercapacitors.

Atomic-Scale Investigations of Self-Assembled Superstructures in Ferroic Materials.

Atomic-Scale Investigations of Self-Assembled Superstructures in Ferroic Materials.

Radioluminescent Cu-Au Metal Nanoclusters: Synthesis and Self-Assembly for Efficient X-ray Scintillation and Imaging.

Zero-dimensional (0D) scintillation materials have drawn tremendous attention due to their inherent advantages in the fabrication of flexible high-energy radiation scintillation screens by solution processes. Although considerable progress has been made in the development of 0D scintillators, such as the current leading lead-halide perovskite nanocrystals and quantum dots, challenges still persist, including potential issues with self-absorption, air stability, and eco-friendliness. Here, we present a strategy to overcome those limitations by synthesis and self-assembly of a new class of scintillators based on metal nanoclusters. We demonstrate the gram-scale synthesis of an atomically precise nanocluster with a Cu-Au alloy core exhibiting high phosphorescence quantum yield, aggregation-induced emission enhancement (AIEE) behavior, and intense radioluminescence. By controlling solvent interactions, the AIEE-active nanoclusters were self-assembled into submicron spherical superparticles in solution, which we exploited as a novel building block for flexible particle-deposited scintillation films with high-resolution X-ray imaging performance. This work reveals metal nanoclusters and their self-assembled superstructures as a promising class of scintillators for practical applications in high-energy radiation detection and imaging.

Monolayer supertubes of Carbon-Armored platinum nanocrystals enabling robust oxygen reduction electrocatalysis

Self-assembled superstructures composed of nanocrystals (NCs) have shown immense potential for enhancing the performance in electrocatalytic applications. However, there has been limited research on the self-assembly of platinum (Pt) into low-dimensional superstructures as efficient electrocatalysts for oxygen reduction reaction (ORR). In this study, we designed a unique tubular superstructure composed of monolayer or sub-monolayer carbon-armored platinum nanocrystals (Pt NCs) using a template-assisted epitaxial assembly approach. The organic ligands on the surface of Pt NCs were in situ carbonized, resulting in few-layer graphitic carbon shells that encapsulate Pt NCs. Due to their monolayer assembly and tubular geometry, the Pt utilization of the supertubes was 1.5 times higher than that of conventional carbon-supported Pt NCs. As a result, such Pt supertubes exhibit remarkable electrocatalytic performance for the ORR in acidic media, with a high half-wave potential of 0.918 V and a high mass activity of 181 A g-1Pt at 0.9 V, which are comparable to commercial carbon-supported Pt (Pt/C) catalysts. Furthermore, the Pt supertubes demonstrate robust catalytic stability, as confirmed by long-term accelerated durability tests and identical-location transmission electron microscopy. This study presents a new approach to designing Pt superstructures for highly efficient and stable electrocatalysis.

Precision Nanocluster-Based Toroidal and Supertoroidal Frameworks Using Photocycloaddition-Assisted Dynamic Covalent Chemistry.

Atomically precise nanoclusters (NCs) have recently emerged as ideal building blocks for constructing self-assembled multifunctional superstructures. The existing structures are based on various non-covalent interactions of the ligands on the NC surface, resulting in inter-NC interactions. Despite recent demonstrations on light-induced reversible self-assembly, long-range reversible self-assembly based on dynamic covalent chemistry on the NC surface has yet to be investigated. Here, it is shown that Au25 NCs containing thiolated umbelliferone (7-hydroxycoumarin) ligands allow [2+2] photocycloaddition reaction-induced self-assembly into colloidal-level toroids. The toroids upon further irradiation undergo inter-toroidal reaction resulting in macroscopic supertoroidal honey-comb frameworks. Systematic investigation using electron microscopy, atomic force microscopy (AFM), and electron tomography (ET) suggest that the NCs initially form spherical aggregates. The spherical structures further undergo fusion resulting in toroid formation. Finally, the toroids fuse into macroscopic honeycomb frameworks. As a proof-of-concept, a cross-photocycloaddition reaction between coumarin-tethered NCs and an anticancer drug (5-fluorouracil) is demonstrated as a model photo-controlled drug release system. The model system allows systematic loading and unloading of the drug during the assembly and disassembly under two different wavelengths. The results suggest that the dynamic covalent chemistry on the NC surface offers a facile route for hierarchical multifunctional frameworks and photocontrolled drug release.

Methanol-water mixture evaporation-induced self-assembly of ZIF-8 particles.

We report a strategy for the self-assembly of zeolitic imidazolate framework-8 (ZIF-8) particles induced by the evaporation of a methanol-water mixture. This strategy effectively suppresses the coffee ring effect, facilitates the rapid assembly of ZIF-8 particles, and improves the orientation and optical properties of self-assembled superstructures.

Pillararene-Based Variable Stoichiometry Co-Crystallization: A Versatile Approach to Diversified Solid-State Superstructures.

Variable stoichiometry co-crystals are important in solid-state supramolecular chemistry as they allow studies of structure-property relationships while permitting the synthesis of new scaffolds using identical synthons. In this work, we extend the concept of variable stoichiometry co-crystals into the realm of pillararene chemistry and show that this permits the rational construction of a diverse set of supramolecular structures in the solid state. Specifically, we report a series of variable stoichiometry co-crystals based on pillar[n]arenes and tetracyanobenzene (TCNB) and show that the combination of in-cavity complexation by pillar[n]arenes (n = 5,6) and outside binding with TCNB allows several types of co-crystals with different self-assembled superstructures to be isolated. The variable stoichiometry co-crystals of this study display different solid-state physicochemical properties, including colors and luminescence features. Among these pillar[n]arene-based co-crystals, we discovered unique crystallographic architectures wherein two sets of individual host-guest complexes co-exist in the solid state. These mixed co-crystal systems allow for vapochromic-based detection of n-bromoalkanes. This work highlights a new strategy for the construction of self-assembled superstructures in the solid state and for tuning their intrinsic characteristics, including their luminescent and substrate-responsive features.

Pillar[5]arene–modified peptide-guanidiniocarbonylpyrrol amphiphiles with gene transfection properties

Pillar[5]arene–modified amphiphilic peptides with varying numbers of guanidiniocarbonylpyrrol (GCP) moieties have been successfully synthesized, which can self-assemble to multivalent cationic superstructures in aqueous solutions. These assembled peptides can condense DNA into various compact multimolecular aggregates to achieve successful intracellular DNA delivery and demonstrate great potential for gene transfection. Transfection efficiencies of the self-assembled superstructures have been evaluated in vitro with HeLa and HEK 293T cells. We demonstrate that GCP moiety could enhance the cell transfection ability, owing to its excellent binding towards cytomembrane. It was also found that subtle structure difference in peptides 2 and 3 could result in distinct transfection efficacy, which makes it possible to gain an in-depth understanding of their structure-activity relationship. This work presents a good example of rational structural design in achieving effective gene transfection vectors.

Dual Atomic Coherence in the Self-Assembly of Patchy Heterostructural Nanocrystals.

Advances in the synthesis and self-assembly of nanocrystals have enabled researchers to create a plethora of different nanoparticle superlattices. But while many superlattices with complex types of translational order have been realized, rotational order of nanoparticle building blocks within the lattice is more difficult to achieve. Self-assembled superstructures with atomically coherent nanocrystal lattices, which are desirable due to their exceptional electronic and optical properties, have been fabricated only for a few selected systems. Here, we combine experiments with molecular dynamics (MD) simulations to study the self-assembly of heterostructural nanocrystals (HNCs), consisting of a near-spherical quantum dot (QD) host decorated with a small number of epitaxially grown gold nanocrystal (Au NC) "patches". Self-assembly of these HNCs results in face-centered-cubic (fcc) superlattices with well-defined orientational relationships between the atomic lattices of both QD hosts and Au patches. MD simulations indicate that the observed dual atomic coherence is linked to the number, size, and relative positions of gold patches. This study provides a strategy for the design and fabrication of NC superlattices with large structural complexity and delicate orientational order.