Synchronous assembly of chiral skeletal single-crystalline microvessels

Synthesis of Mono-, Di-, Tri-, and Tetra-cationic Pyridinium and Vinylpyridinium Modified [2.2]Paracyclophanes: Modular Receptors for Supramolecular Systems

In this report, a new series of mono-, di-, tri-, and tetra-cationic pyridinium and vinyl pyridinium-modified [2.2]paracyclophanes as useful molecular tectons for supramolecular systems are described. Regioselective functionalization at specific positions, followed by resolution step and successive transformations through Pd-catalyzed Suzuki-Miyaura and Mizoroki-Heck cross-coupling chemistry furnish a series of modular PCP scaffolds. In our proof-of-concept study, on N-methylation, the PCPs bearing (cationic) pyridyl functionalities were demonstrated as useful molecular receptors in host-guest supramolecular assays. The PCPs on grafting with light-responsive azobenzene (-N=N-) functional core as side-groups impart photosensitivity that can be remotely transformed on irradiation, offering photo-controlled smart molecular functions. Furthermore, the symmetrical PCPs bearing bi-, and tetra-pyridyl functionalities at the peripheries have enormous potential to serve as ditopic and tetratopic 3D molecular tectons for engineering non-covalent supramolecular assemblies with new structural and functional attributes.

Insight from Boric Acid into Bioskeleton Formation: Inscribed Circle Effect on the Edge-Base Plate Growth

Complex morphologies in nature often arise from the assembly of elemental building blocks, leading to diverse and intricate structures. Understanding the mechanisms that govern the formation of these complex morphologies remains a significant challenge. In particular, the edge-base plate growth of biogenic crystals plays a crucial role in directing the development of intricate bioskeleton morphologies. However, the factors and regulatory processes that govern edge-base plate growth remain insufficiently understood. Inspired by biological skeletons and based on the soluble property of boric acid (BA) in both water and alcohols, we obtained a series of novel BA morphologies, including coccolith, and anemone biological skeletons. Here, we unveil the "inscribed circle effect", a concise mathematical model that reveals the underlying causative factors and regulatory mechanisms driving edge-base plate growth. Our findings illuminate how variations in solvent environments can exert control over the edge-base plate growth pathways, thereby resulting in the formation of diverse and complex morphologies. This understanding holds significant potential for guiding the chemical synthesis of bioskeleton materials.

Liquid-Liquid and Liquid-Solid Interfacial Nanoarchitectonics

Nanoscale science is becoming increasingly important and prominent, and further development will necessitate integration with other material chemistries. In other words, it involves the construction of a methodology to build up materials based on nanoscale knowledge. This is also the beginning of the concept of post-nanotechnology. This role belongs to nanoarchitectonics, which has been rapidly developing in recent years. However, the scope of application of nanoarchitectonics is wide, and it is somewhat difficult to compile everything. Therefore, this review article will introduce the concepts of liquid and interface, which are the keywords for the organization of functional material systems in biological systems. The target interfaces are liquid-liquid interface, liquid-solid interface, and so on. Recent examples are summarized under the categories of molecular assembly, metal-organic framework and covalent organic framework, and living cell. In addition, the latest research on the liquid interfacial nanoarchitectonics of organic semiconductor film is also discussed. The final conclusive section summarizes these features and discusses the necessary components for the development of liquid interfacial nanoarchitectonics.

π-Diamond: A Diamondoid Superstructure Driven by π-Interactions

Modulating the arrangement of superstructures through noncovalent interactions has a significant impact on macroscopic shape and the expression of unique properties. Constructing π-interaction-driven hierarchical three-dimensional (3D) superstructures poses challenges on account of limited directional control and weak intermolecular interactions. Here we report the construction of a 3D diamondoid superstructure, named π-Diamond, employing a ditopic strained Z-shaped building block comprising a porphyrin unit as bow-limb double-strapped with two m-xylylene units as bowstrings. This superstructure, reminiscent of diamond's tetrahedral carbon composition, is composed of double-walled tetrahedron (DWT) driven solely by π-interactions. Hetero-π-stacking interactions between porphyrin and m-xylylene panels drive the assembly of four building blocks predominantly into a DWT, which undergoes extension to create an adamantane unit and eventually a diamondoid superstructure wherein each porphyrin panel is shared by two neighboring tetrahedra through hetero-π-stacking. π-Diamond exhibits a solid-state fluorescent quantum yield 44 times higher than that of tetraphenylporphyrin along with excellent photocatalytic performance. The precise 3D directionality of π-interactions, achieved through strained multipanel building blocks, revolutionizes the assembly of hierarchical 3D superstructures driven by π-interactions.

Organic Phosphorescent Hopper-Shaped Microstructures

Hopper-shaped microcrystals, an unusual type of crystal with a large specific surface area, are promising for use in catalysis, drug delivery, and gas sensors. In contrast to well-studied inorganic hopper-shaped crystals, organic phosphorescent concave hopper-shaped microstructures are rarely reported. This study reports the synthesis of two types of organic stepped indented hopper-shaped microstructures with efficient room temperature phosphorescence (RTP) using a liquid phase self-assembly strategy. The formation mechanism is attributed to the interfacial instability induced by the concentration gradient and selective etching. Compared with flat microstructures, the stepped indented hopper-like RTP microstructures exhibit high sensitivity to oxygen. This work also demonstrates that packing the photochromic material into the concave hopper "vessel" effectively controls the switch of phosphorescence from energy transfer, expanding the potential applications of phosphorescent materials.

Recent Advances of Chiral Isolated and Small Organic Molecules: Structure and Properties for Circularly Polarized Luminescence

This paper explores recent advancements in the field of circularly polarized luminescence (CPL) exhibited by small and isolated organic molecules. The development and application of small CPL molecule are systematically reviewed through eight different chiral skeleton sections. Investigating the intricate interplay between molecular structure and CPL properties, the paper aims at providing and enlighting novel strategies for CPL-based applications.

Rational Electrochemical Design of Cuprous Oxide Hierarchical Microarchitectures and Their Derivatives for SERS Sensing Applications

Rational morphology control of inorganic microarchitectures is important in diverse fields, requiring precise regulation of nucleation and growth processes. While wet chemical methods have achieved success regarding the shape-controlled synthesis of micro/nanostructures, accurately controlling the growth behavior in real time remains challenging. Comparatively, the electrodeposition technique can immediately control the growth behavior by tuning the overpotential, whereas it is rarely used to design complex microarchitectures. Here, the electrochemical design of complex Cu2O microarchitectures step-by-step by precisely controlling the growth behavior is demonstrated. The growth modes can be switched between the thermodynamic and kinetic modes by varying the overpotential. Cl- ions preferably adhered to {100} facets to modulate growth rates of these facets is proved. The discovered growth modes to prepare Cu2O microarchitectures composed of multiple building units inaccessible with existing methods are employed. Polyvinyl alcohol (PVA) additives can guarantee all pre-electrodeposits simultaneously evolve into uniform microarchitectures, instead of forming undesired microstructures on bare electrode surfaces in following electrodeposition processes is discovered. The designed Cu2O microarchitectures can be converted into noble metal microstructures with shapes unchanged, which can be used as surface-enhanced Raman scattering substrates. An electrochemical avenue toward rational design of complex inorganic microarchitectures is opened up.

Confined Space Nanoarchitectonics for Dynamic Functions and Molecular Machines

Nanotechnology has advanced the techniques for elucidating phenomena at the atomic, molecular, and nano-level. As a post nanotechnology concept, nanoarchitectonics has emerged to create functional materials from unit structures. Consider the material function when nanoarchitectonics enables the design of materials whose internal structure is controlled at the nanometer level. Material function is determined by two elements. These are the functional unit that forms the core of the function and the environment (matrix) that surrounds it. This review paper discusses the nanoarchitectonics of confined space, which is a field for controlling functional materials and molecular machines. The first few sections introduce some of the various dynamic functions in confined spaces, considering molecular space, materials space, and biospace. In the latter two sections, examples of research on the behavior of molecular machines, such as molecular motors, in confined spaces are discussed. In particular, surface space and internal nanospace are taken up as typical examples of confined space. What these examples show is that not only the central functional unit, but also the surrounding spatial configuration is necessary for higher functional expression. Nanoarchitectonics will play important roles in the architecture of such a total system.

Lateral epitaxial growth of two-dimensional organic heterostructures

Two-dimensional organic lateral heterostructures (2D OLHs) are attractive for the fabrication of functional materials. However, it is difficult to control the nucleation, growth and orientation of two distinct components. Here we report the combination of two methods-liquid-phase growth and vapour-phase growth-to synthesize 2D OLHs from perylene and a perylenecarboxaldehyde derivative, with a lateral size of ~20 μm and a tunable thickness ranging from 20 to 400 nm. The screw dislocation growth behaviour of the 2D crystals shows the spiral arrangement of atoms within the crystal lattice, which avoids volume expansion and contraction of OLH, thereby minimizing lateral connection defects. Selective control of the nucleation and sequential growth of 2D crystals leads to structural inversion of the 2D OLHs by the vapour-phase growth method. The resulting OLHs show good light-transport capabilities and tunable spatial exciton conversion, useful for photonic applications. This synthetic strategy can be extended to other families of organic polycyclic aromatic hydrocarbons, as demonstrated with other pyrene and perylene derivatives.

Aggregation-induced emission from optically active X-shaped molecules based on planar chiral [2.2]paracyclophane

An optically active π-stacked molecule was synthesized incorporating planar chiral [2.2]paracyclophane and o-carborane units to impart circularly polarized luminescence and aggregation-induced emission properties to the molecule. The molecule exhibited a strong emission from the aggregated state in a mixed solvent system (H2O/THF) and the solid state in the PMMA matrix. In the aggregated state, weak circularly polarized luminescence was observed owing to the random intermolecular orientation. On the other hand, the circularly polarized luminescence was clearly observed in the PMMA film containing 1 wt% molecule. Theoretical studies using time-dependent density functional theory reproduced the molecule's circular dichroism and circularly polarized luminescence properties.

Achiral Dichroic Dyes-mediated Circularly Polarized Emission Regulated by Orientational Order Parameter through Cholesteric Liquid Crystals

It is noteworthy that cholesteric liquid crystal (CLC) platforms have been witnessed in high-performance circularly polarized luminescence (CPL) behaviors through the highly organized chiral co-assembled arrangement of achiral dyes. However, most CPL-active design strategies are closely relative to the helix co-assembly structure of CLC rather than achiral dyes. Herein, we developed an intriguing regulation strategy for CPL-active CLC materials. They were regulated using the orientational order parameter (SF ) of achiral dichroic dyes as an incisive probe for the order arrangement degree of achiral dyes in CLC media. The I-shaped phenothiazine derivative PHECN dye (SF =0.30) emitted a strong CPL signal (|glum |=0.47). In contrast, the T-shaped derivative (PHEBen) dye (SF =0.09) showed a weak circular polarization level (|glum |=0.07) at similar CLC textures. Most interestingly, this kind of dichroic PHECN dye with a higher SF could greatly improve the contrast ratio of CPL (Δglum =0.47) and emission intensity (ΔFL=46.0 %) at direct-current electric field compared with the T-shaped PHEBen (Δglum =0.07 and ΔFL=1.0 %) in CLC. This work demonstrates that an induced CPL emission can be mediated using achiral dichroic dye, which will open a new avenue for developing excellent CPL-active display materials.

Unrestricted Chiral Patterning by Laser Writing in Liquid Crystalline and Plasmonic Nanocomposite Thin Films

Obtaining hierarchical structures with arbitrarily controlled chirality remains a challenge. Here, thin films featuring chiroptically bipolar patterns are produced by a device utilizing microscale photothermal re-melting of materials exhibiting chirality synchronization. This device operates autonomously, guided by an algorithm that facilitates the homochiral growth of supramolecular organic helices through controlling their re-melting. The chirality synchronization phenomena of constitutionally achiral molecules grants availability of both handednesses of the helices, enabling unrestricted chiral writing in the film. The collective chiroptical response of assembled molecules is utilised to guide the patterning process, creating a foundation for optically secured information. The established methodology enables achieving dissymmetry factor values for circular dichroism (CD) a magnitude higher than previously reported, as confirmed with state-of-the-art, synchrotron-based Mueller matrix polarimetry (MMP). Moreover, the developed method is extended to nanocomposites comprising gold nanoparticles, providing the opportunity to tune the CD toward the plasmonic region. This strategic application of photothermal processing, specifically laser-directed melting, uncovers the potential to broaden the selection of nanostructured materials with precisely designed functionalities for photonic applications.

Factors Controlling Complex Morphologies of Isomorphous Metal-Organic Frameworks

We demonstrate here how nitrate salts of bivalent copper, nickel, cobalt, and manganese, along with an achiral organic ligand, assemble into various structures such as symmetrical double-decker flowers, smooth elongated hexagonal bipyramids, and hexagonal prisms. Large morphological changes occur in these structures because of different metal cations, although they maintain isomorphous hexagonal crystallographic structures. Metal cations with stronger coordination to ligands (Cu and Ni) tend to form uniform crystals with unusual shapes, whereas weaker coordinating metal cations (Mn and Co) produce crystals with more regular hexagonal morphologies. The unusual flower-like crystals formed with copper nitrate have two pairs of six symmetrical petals with hexagonal convex centers. The texture of the petals indicates dendritic growth. Two different types of morphologies were formed by using different copper nitrate-to-ligand ratios. An excess of the metal salt results in uniform and hexagonal crystals having a narrow size distribution, whereas the use of an excess of ligand results in double-decker morphologies. Mechanistically, an intermediate structure was observed with slightly concave facets and a domed center. Such structures most likely play a key role in the formation of double-decker crystals that can be formed by fusion processes. The coordination chemistry results in isostructural chiral frameworks consisting of two types of continuous helical channels. Four pyridine units from four separate ligands are coordinated to the metal center in a plane having a chiral (propeller-type) arrangement. The individual double-decker flower crystals are homochiral and a batch consists of crystals having both handedness.

Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit

Unveiling the structural evolution of single-crystalline compounds based on certain building units may help greatly in guiding the design of complex structures. Herein, a series of praseodymium antimony oxohalide crystals have been isolated under solvothermal conditions via adjusting the solvents used, that is, [HN(CH2CH3)3][FeII(2,2′-bpy)3][Pr4Sb12O18Cl15]·EtOH (1) (2,2′-bpy = 2,2′-bipyridine), [HN(CH2CH3)3][FeII(2,2′-bpy)3]2[Pr4Sb12O18Cl14)2Cl]·N(CH2CH3)3·2H2O (2), and (H3O)[Pr4Sb12O18Cl12.5(TEOA)0.5]·2.5EtOH (3) (TEOA = mono-deprotonated triethanolamine anion). Single-crystal X-ray diffraction analysis revealed that all the three structures feature an anionic zig-zag chain of [Pr4Sb12O18Cl15−x]n as the tertiary building unit (TBU), which is formed by interconnections of praseodymium antimony oxochloride clusters (denoted as {Pr4Sb12}) as secondary building units. Interestingly, different arrangements or linkages of chain-like TBUs result in one-dimensional, two-dimensional layered, and three-dimensional structures of 1, 2, and 3, respectively, thus demonstrating clearly the structural evolution of metal oxohalide crystals. The title compounds have been characterized by elemental analysis, powder X-ray diffraction, thermogravimetric analysis, and UV-Vis spectroscopy, and the photodegradation for methyl blue in an aqueous solution of compound 1 has been preliminarily studied. This work offers a way to deeply understand the assembly process of intricate lanthanide-antimony(III) oxohalide structures at the atomic level.

Single-Crystal Superstructures via Hierarchical Assemblies of Giant Rubik's Cubes as Tertiary Building Units

Intricate superstructures possess unusual structural features and promising applications. The preparation of superstructures with single-crystalline nature are conducive to understanding the structure-property relationship, however, remains an intriguing challenge. Herein we put forward a new hierarchical assembly strategy towards rational and precise construction of intricate single-crystal superstructures. Firstly, two unprecedented superclusters in Rubik's cube's form with a size of ≈2×2×2 nm³ are constructed by aggregation of eight {Pr₄ Sb₁₂ } oxohalide clusters as secondary building units (SBUs). Then, the Rubik's cubes further act as isolable tertiary building units (TBUs) to assemble diversified single-crystal superstructures. Importantly, intermediate assembly states are captured, which helps illustrate the evolution of TBU-based superstructures and thus provides a profound understanding of the assembly process of superstructures at the atomic level.

Stacking Cyclophanes into Chiral Microvessels

Engineering novel micro-/nanoscale systems and devices based on supramolecular assembly has tremendous potential from diverse applications perspective. However, controlling the size, shape, spatial arrangements, and hierarchical transcription by a dimensional organizing principle (1D-3D arrangement) without the help of templates remains a challenging task. In this vein, a recent study by Oki and colleagues reporting the stacking of chiral cyclophanes via intermolecular non-covalent interactions for crafting synchronous microcrystalline 3D chiral vessels with controlled conformational arrangements represents a truly remarkable illustration of molecular engineering. The microvessels bear stereocontrolled skeletal morphology, recognize stereoisomers and serve as containers to accommodate microcrystals, polymer particles, and fluorescent dyes. The full application scope of this fascinating research is far beyond non-covalent interactions, supramolecular self-assembly, and crystal engineering.

Synthesis of Two Novel Optically Active #-Shaped Cyclic Tetramers Based on Planar Chiral [2.2]Paracyclophanes

This study reports the synthesis of optically active cyclic tetramers comprising four stacked π-electron systems from two enantiomerically pure [2.2]paracyclophane compounds (bis-(para)-pseudo-ortho- and bis-(para)-pseudo-meta-tetrasubstituted [2.2]paracyclophane compounds). Depending on the combination of the absolute configurations of the planar chiral pseudo-ortho- and pseudo-meta-[2.2]paracyclophane units, the cyclic tetramers formed either parallel-#- or weave-#-structures. The optical and chiroptical properties of both structures were investigated experimentally and theoretically. In particular, the weave-#-shaped cyclic tetramer exhibited good chiroptical properties and emitted circularly polarized luminescence (CPL) with a high anisotropy factor (|g_lum | value of the order of 10^-3 ) and a CPL brightness (B_CPL ) higher than 100.

Crystallographic-Morphological Connections in Star Shaped Metal-Organic Frameworks

The symmetry of a crystal's morphology usually reflects the symmetry of the crystallographic packing. For single crystals, the space and point groups allow only a limited number of mathematical descriptions of the morphology (forms), all of which are convex polyhedrons. In contrast, concave polyhedrons are a hallmark of twinning and polycrystallinity and are typically inconsistent with single crystallinity. Here we report a new type of structure: a concave polyhedron shape single crystal having a multidomain appearance and a rare space group (P622). Despite these unusual structural features, the hexagonal symmetry is revealed at the morphological levels.