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Morphology of toroids. a) Larger area FESEM image of self‐assembled toroids and b) zoomed‐in and focused image of a single toroid. c,d) AFM images c) topography, d) amplitude and corresponding (d1) height profile of a single toroid captured after 8 h of illumination. e) Elemental spectrum collected from the toroid. f,g) 3D reconstructed tomograms of a toroid shown in different orientations.
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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 s...
Citations
... Shibu et al. demonstrated reversible [2 þ 2] photocyclization reactionassisted self-assembly of coumarin-protected atomically precise Au25 nanoclusters (NCs) (atomic-level precision NCs) (MS17) (Figure 17). [108] Irradiation of the NCs at 365 nm facilitates inter-NC coupling by cycloaddition reaction, resulting in a homogeneous annular superstructure. Transient spherical structures formed undergo fusion and transform into rings. ...
Smart materials serve as the fundamental cornerstone supporting humanity's transition into the intelligent era. Smart materials possess the capability to perceive external stimuli and respond accordingly. Light‐controlled smart materials (LCSMs) are a significant category that can sense and respond to light stimuli. Light, being a non‐invasive, precisely regulated, and remotely controllable source of physical stimulation, makes LCSMs indispensable in certain application scenarios. Recently, the construction of LCSMs using supramolecular strategies has emerged as a significant research focus. Supramolecular assembly, based on non‐covalent bonding, offers dynamic, reversible, and biomimetic properties. By integrating supramolecular systems with photoresponsive molecular building blocks, these materials can achieve synergistic and rich intelligent stimulus responses. This review delves into the latest research advancements in LCSMs based on supramolecular strategies. There are four sections in this review. The first section defines LCSMs and outlines their advantages. The second section discusses the design approaches of supramolecular LCSMs. The third section highlights the latest advancements on supramolecular LCSMs over the past 3 years. The fourth section summarizes the current research and provides insights into the future development of this field.
... [9] Inspired by the natural toroidal superstructures, many synthetic approaches have been developed to construct and mimic the structure and function of the nature-born toroids. [10][11][12] Accordingly, a variety of chiral, [13,14] amphiphilic, [15] macrocyclic, [16,17] rosette, [18,19] peptide, [20] nanocluster [21] and polymeric [22][23][24][25] substrates and building blocks have been employed for the fabrication of the nanostructured toroids. Polydiacetylenes (PDAs) are a class of conjugated polymers formed by the 1,4-addition polymerization of diacetylene (DA) units, exhibiting unique color and fluorescence properties. ...
Functional supramolecular materials exhibit important features including structural versatility and versatile applications. Here, this study reports the construction of unique hierarchically organized nanotoroids exhibiting fluorescence, photocatalytic, and sensing properties. The nanotoroids comprise of macrocyclic diacetylenes (MCDA) and 8‐anilino‐1‐naphthalene sulfonate (ANS), a negatively charged aromatic fluorescent dye. This study shows that the hierarchical structure of the nanotoroids consist of MCDA nanofibers formed by stacked diacetylene monomers as the basic units, which are further bent and aligned into toroidal organization by electrostatic and hydrophobic interactions with the ANS molecules. The amine moieties on the nanotoroids surface are employed for deposition of gold nanostructures – Au nanoparticles or Au nanosheets – which constitute effective platforms for photocatalysis and surface enhanced Raman scattering (SERS)‐based sensing.
... Recently, surface photochemistry has been intensively studied, due to its powerful function for tunning SAMs' ordering and initiating on-surface polymerization, including photoisomerization [42,43], photopolymerization [44,45] and photocycloaddition [46,47]. The SAM adlayer normally experiences significant structural changes as a result of surface photochemical reactions, primarily due to the substantial structural disparity between the photo-active molecules before and after the photo-induction. ...
The phenomenon of ordered self-assembly on solid substrates is a topic of interest in both fundamental surface science research and its applications in nanotechnology. The regulation and control of two-dimensional (2D) self-assembled supra-molecular structures on surfaces have been realized through applying external stimuli. By utilizing scanning tunneling microscopy (STM), researchers can investigate the detailed phase transition process of self-assembled monolayers (SAMs), providing insight into the interplay between intermolecular weak interactions and substrate–molecule interactions, which govern the formation of molecular self-assembly. This review will discuss the structural transition of self-assembly probed by STM in response to external stimuli and provide state-of-the-art methods such as tip-induced confinement for the alignment of SAM domains and selective chirality. Finally, we discuss the challenges and opportunities in the field of self-assembly and STM.
... Recently, surface photochemistry has been intensively studied, due to its powerful function for tunning SAMs' ordering and initiating on-surface polymerization, including photoisomerization [42,43], photopolymerization [44,45] and photocycloaddition [46,47]. The SAM adlayer normally experiences significant structural changes as a result of surface photochemical reactions, primarily due to the substantial structural disparity between the photo-active molecules before and after the photo-induction. ...
The phenomenon of ordered self-assembly on solid substrates is a topic of interest in both fundamental surface science research and its applications in nanotechnology. The regulation and control of two-dimensional (2D) self-assembled supra-molecular structures on surfaces have been realized through applying external stimuli. By utilizing scanning tunneling microscopy (STM), researchers can investigate detailed phase transition process about self-assembled monolayers (SAMs), providing insight into the interplay between intermolecular weak interactions and substrate-molecule interactions, which govern the formation of molecular self-assembly. This review will discuss the structural transition of self-assembly probed by STM in response to external stimuli and provide state-of-art methods such as tip induced confinement for the alignment of SAM domains and selective chirality. Finally, we discuss the challenges and opportunities in the field of self-assembly and STM.
Self‐emissive atomically precise metal nanoclusters (NCs) are emerging as promising emissive layer material for next‐generation light‐emitting diodes (LEDs), thanks to their solid‐state luminescence, well‐defined structures, photo/thermal stability, low toxicity, and unique excited‐state properties. However, achieving high external quantum efficiency (EQE) in solid‐state NCs remains a formidable challenge. In this study, a highly stable bimetallic gold‐copper NC forming [Au2Cu6(Sadm)6(DPPEO)2] stabilized with 1‐adamantanethiol (HSadm) and 1,2‐bis(diphenylphosphino)ethane (DPPE) as the primary and secondary ligands, respectively is reported. Single‐crystal X‐ray diffraction and spectroscopic analyses suggest that the as‐synthesized NC contains one phosphine bound to gold and the second phosphine has oxidized to phosphine oxide (P═O). The presence of such P═O moieties in the NC facilitated C─H···O interactions along with C─H···π and H···H interactions between ligands, promoting rapid crystallization. Due to the exceptional photo/thermal stability and enhanced solid‐state photoluminescence quantum yield (PLQY), [Au2Cu6(Sadm)6(DPPEO)2] NC is utilized to fabricate the NC‐based LED (NC‐LED) via the solution‐processed technique, without using any additional host materials. The fabricated NC‐LED shows a maximum brightness of 1246 cd m⁻² and an EQE of 12.60% with a pure red emission ≈668 nm. This EQE value coupled with saturated pure red emission is the best among solution‐processed and non‐doped NC‐LEDs, suggesting the enormous potential of the NCs for electro‐optical devices.
A robust hydrogen evolution is demonstrated from Au25(PET)18]⁻ nanoclusters (PET = 2‐phenylethanethiol) grafted with minimal platinum atoms. The fabrication involves an electrochemical activation of nanoclusters by partial removal of thiols, without affecting the metallic core, which exposes Au‐sites adsorbed with hydrogen and enables an electroless grafting of platinum. The exposed Au‐sites feature the (111)‐facet of the fcc‐Au25 nanoclusters as assessed through lead underpotential deposition. The electrochemically activated nanoclusters (without Pt loading) show better electrocatalytic reactivity toward hydrogen evolution reaction than the pristine nanoclusters in an acidic medium. The platinum‐grafted nanocluster outperformed with a lower overpotential of 0.117 V vs RHE (RHE = Reversible Hydrogen Electrode) compared to electrochemically activated nanoclusters (0.353 V vs RHE ) at 10 mA cm⁻² and is comparable with commercial Pt/C. The electrochemically activated nanoclusters show better reactivity at higher current density owing to the ease of hydrogen release from the active sites. The modified nanoclusters show unique supramolecular self‐assembly characteristics as observed in electron microscopy and tomography due to the possible metallophilic interactions. These results suggest that the post‐surface modification of nanoclusters will be an ideal tool to address the sustainable production of green hydrogen.
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.
As nanotechnology continues to push the boundaries across disciplines, there is an increasing need for engineering nanomaterials with atomic-level precision for self-assembly across length scales, i.e., from the nanoscale to the macroscale. Although molecular self-assembly allows atomic precision, it faces challenges to extend beyond certain length scales. Therefore, attention has turned to the size and shape-controlled metal nanoparticles as building blocks for multifunctional colloidal self-assemblies. However, traditionally, metal nanoparticles suffer from polydispersity, uncontrolled aggregation, and inhomogeneous ligand distribution, resulting in heterogeneous end products. In this feature article, I will discuss how virus capsids provide clues for designing subunit-based, precise, efficient, and error-free self-assembly of colloidal molecules. The atomically precise nanoscale proteinic subunits of capsids display rigidity (conformational and structural) and patchy distribution of interacting sites. Recent experimental evidence suggests that atomically precise noble metal nanoclusters display anisotropic distribution of ligands and patchy ligand bundles. This enables symmetry breaking, consequently offering a facile route for two-dimensional colloidal crystals, bilayers, and elastic monolayer membranes. Furthermore, inter-nanocluster interactions mediated via the ligand functional groups are versatile, offering routes for discrete supracolloidal capsids, composite cages, toroids, and macroscopic hierarchically porous frameworks. Therefore, engineered nanoparticles with atomically precise structures have the potential to overcome the limitations of molecular self-assembly and large colloidal particles. The self-assembly allows the emergence of new optical properties, mechanical strength, photothermal stability, catalytic efficiency, quantum yield, and biological properties. The self-assembled structures allow reproducible optoelectronic properties, mechanical performance, and accurate sensing. More importantly, the intrinsic properties of individual nanoclusters are retained across length scales. The atomically precise nanoparticles offer enormous potential for next-generation functional materials, optoelectronics, precision sensors, and photonic devices.
