Interlocked Structures Research Articles

A Flexible Smart Healthcare Platform Conjugated with Artificial Epidermis Assembled by Three-Dimensionally Conductive MOF Network for Gas and Pressure Sensing

The rising flexible and intelligent electronics greatly facilitate the noninvasive and timely tracking of physiological information in telemedicine healthcare. Meticulously building bionic-sensitive moieties is vital for designing efficient electronic skin with advanced cognitive functionalities to pluralistically capture external stimuli. However, realistic mimesis, both in the skin’s three-dimensional interlocked hierarchical structures and synchronous encoding multistimuli information capacities, remains a challenging yet vital need for simplifying the design of flexible logic circuits. Herein, we construct an artificial epidermal device by in situ growing Cu3(HHTP)2 particles onto the hollow spherical Ti3C2Tx surface, aiming to concurrently emulate the spinous and granular layers of the skin’s epidermis. The bionic Ti3C2Tx@Cu3(HHTP)2 exhibits independent NO2 and pressure response, as well as novel functionalities such as acoustic signature perception and Morse code-encrypted message communication. Ultimately, a wearable alarming system with a mobile application terminal is self-developed by integrating the bimodular senor into flexible printed circuits. This system can assess risk factors related with asthmatic, such as stimulation of external NO2 gas, abnormal expiratory behavior and exertion degrees of fingers, achieving a recognition accuracy of 97.6% as assisted by a machine learning algorithm. Our work provides a feasible routine to develop intelligent multifunctional healthcare equipment for burgeoning transformative telemedicine diagnosis.

Bioinspired Soft Pressure Sensors with Interlocked Structures Based on 3D Printing Methods

Bioinspired Soft Pressure Sensors with Interlocked Structures Based on 3D Printing Methods

Synthesis of Adhesive Polyrotaxanes Through Sequential Self-Assembly via Supramolecular Interactions and Dynamic Covalent Interactions.

Self-assembly is an effective approach to construct complicated structures. Polyrotaxanes (PRs) as one of the typical polymer types with complex structure, own interlocked structures and dynamic components, in which it results in unique characteristics and functions. Currently, the synthesis of which involves covalent reactions to hinder the development of polyrotaxanes. Herein, we employed supramolecular interactions as well as dynamic covalent bonds to synthesize PRs by sequential self-assembly. First, we prepared M1 possessing two diamine structures and M2 of a bisammonium salt with two dibenzylammonium (DBA) units modified by two stoppers at its ends, then M1 and M2 self-assembled into supramolecular polymers stemming from hydrogen bonding of [N+-H ⋅ ⋅ ⋅ O] under high concentrations. After adding 2,6-pyridinedicarboxaldehyde (M3), the imine bond formation enabled the generation of macrocycles, transforming supramolecular polymers into PRs. Besides, the solution of polyrotaxanes was applied as the adhesive for diverse hard and soft materials. This strategy provides an important approach for synthesizing PRs, accelerating the advances of mechanically interlocked polymers.

Synthesis of All-Peptide-Based Rotaxane from a Proline-Containing Cyclic Peptide.

Rotaxane cross-linkers enhance the toughness of the resulting rotaxane cross-linked polymers through a stress dispersion effect, which is attributed to the mobility of the interlocked structure. To date, the compositional diversity of rotaxane cross-linkers has been limited, and the poor compatibility of these cross-linkers with peptides and proteins has made their use in such materials challenging. The synthesis of a rotaxane composed of peptides may result in a biodegradable cross-linker that is compatible with peptides and proteins, allowing the fortification of polypeptides and proteins and ultimately leading to the development of innovative materials that possess excellent mechanical properties and biodegradability. However, the chemical synthesis of all-peptide-based rotaxanes has remained elusive because of the absence of strong binding motifs in peptides, which prevents an axial peptide from penetrating a cyclic peptide. Here, we synthesized all-peptide-based rotaxanes using an active template method for proline-containing cyclic peptides. The results of molecular dynamics simulations suggested that cyclic peptides with an expansive inner cavity and carbonyl oxygens oriented toward the center are favorable for rotaxane synthesis. This rotaxane synthesis method is expected to accelerate the synthesis of peptides and proteins with mechanically interlocked structures, potentially leading to the development of peptide- and protein-based materials with unprecedented functionalities.

A High‐Yielding Active Template Click Reaction (AT−CuAAC) for the Synthesis of Mechanically Interlocked Nanohoops

AbstractMechanically interlocked molecules (MIMs) represent an exciting yet underexplored area of research in the context of carbon nanoscience. Recently, work from our group and others has shown that small carbon nanotube fragments—[n]cycloparaphenylenes ([n]CPPs) and related nanohoop macrocycles—may be integrated into mechanically interlocked architectures by leveraging supramolecular interactions, covalent tethers, or metal‐ion templates. Still, available synthetic methods are typically difficult and low yielding, and general methods that allow for the creation of a wide variety of these structures are limited. Here we report an efficient route to interlocked nanohoop structures via the active template Cu‐catalyzed azide‐alkyne cycloaddition (AT−CuAAC) reaction. With the appropriate choice of substituents, a macrocyclic precursor to 2,2′‐bipyridyl embedded [9]CPP (bipy[9]CPP) participates in the AT−CuAAC reaction to provide [2]rotaxanes in near‐quantitative yield, which can then be converted into the fully π‐conjugated catenane structures. Through this approach, two nanohoop[2]catenanes are synthesized which consist of a bipy[9]CPP catenated with either Tz[10]CPP or Tz[12]CPP (where Tz denotes a 1,2,3‐triazole moiety replacing one phenylene ring in the [n]CPP backbone).

A High-Yielding Active Template Click Reaction (AT-CuAAC) for the Synthesis of Mechanically Interlocked Nanohoops.

Mechanically interlocked molecules (MIMs) represent an exciting yet underexplored area of research in the context of carbon nanoscience. Recently, work from our group and others has shown that small carbon nanotube fragments-[n]cycloparaphenylenes ([n]CPPs) and related nanohoop macrocycles-may be integrated into mechanically interlocked architectures by leveraging supramolecular interactions, covalent tethers, or metal-ion templates. Still, available synthetic methods are typically difficult and low yielding, and general methods that allow for the creation of a wide variety of these structures are limited. Here we report an efficient route to interlocked nanohoop structures via the active template Cu-catalyzed azide-alkyne cycloaddition (AT-CuAAC) reaction. With the appropriate choice of substituents, a macrocyclic precursor to 2,2'-bipyridyl embedded [9]CPP (bipy[9]CPP) participates in the AT-CuAAC reaction to provide [2]rotaxanes in near-quantitative yield, which can then be converted into the fully π-conjugated catenane structures. Through this approach, two nanohoop[2]catenanes are synthesized which consist of a bipy[9]CPP catenated with either Tz[10]CPP or Tz[12]CPP (where Tz denotes a 1,2,3-triazole moiety replacing one phenylene ring in the [n]CPP backbone).

Pre-hydrogenation metallurgy for Ti-3Al-5Mo-4.5V alloy with high density and mechanical properties

The present work proposes a novel master-alloy pre-hydrogenation powder metallurgy (MAPH) method to fabricate the TC16 (Ti-3Al-5Mo-4.5V) alloy, which overcomes the challenge of low sintering density due to the high percentage of alloying powders (APs) and the presence of Mo element. The relative density of sintered TC16 alloys increases with the Ti-addition in APs, i.e., ∼99.2% and ∼99.4% for sintered TC16 alloys based on pre-hydrogenated 7.5Ti-3Al-5Mo-4.5V (7.5TiMA-Hx) and 12.5Ti-3Al-5Mo-4.5V (12.5TiMA-Hx) powders, respectively. The APs were successfully modified to be brittle and hydrogen-containing, which exhibits similar pressing and sintering characteristics as TiH2 powders. The increased relative density could be ascribed to the brittleness of 7.5/12.5TiMA-Hx, in which particles show sharp corners that can form interlocked structures with TiH2 particles during pressing. Furthermore, the 7.5/12.5TiMA-Hx and TiH2 powder particles release H2 and shrink simultaneously during sintering, which minimizes the difference in volume mismatch between particles and promotes elemental diffusion. The sintered TC16-7.5TiMA-Hx alloy achieves excellent mechanical properties, i.e., an ultimate tensile strength of ∼1004.6 MPa, a yield strength of ∼934.2 MPa and an elongation of ∼15.8%, due to the low porosity and acceptable impurity contents. However, the excessive O and N elements in the sintered TC16-12.5TiMA-Hx alloy can induce premature intergranular fracture, resulting in decreased ductility. Therefore, the innovative MAPH technique is promising in obtaining high density sintered Ti alloys with excellent mechanical properties.

Hetero- and Homointerlocked Metal-Organic Cages.

Interlocked molecular assemblies constitute a captivating ensemble of chemical topologies, comprising two or more separate components that exhibit remarkably intricate structures. The interlocked molecular assemblies are typically identical, and heterointerlocked systems that comprise structurally distinct assemblies remain unexplored. Here, we demonstrate that metal-templated synthesis can be exploited to afford not only a homointerlocked cage but also a heterointerlocked cage. Treatment of a carboxylated 2,9-dimethyl-1,10-phenanthroline (dmp) or Cu(I) bis-dmp linker with a Ni4-p-tert-butylsulfonylcalix[4]arene cluster affords noninterlocked octahedron and quadruply interlocked double cages consisting of two identical tetragonal pyramids, respectively. In contrast, when a mixture of dmp and Cu(I) bis-dmp linkers is used, a quadruply heterointerlocked cage is produced, consisting of a tetragonal pyramid and an octahedron. With photoredox-active [Cu(dmp)2]+ in the structures, both interlocked cages exhibit remarkable performance as photocatalysts for atom transfer radical addition (ATRA) reactions of trifluoromethanesulfonyl chloride with alkenes or oxo-azidations of vinyl arenes. These interlocked structures serve the dual purpose of stabilizing photocatalytically active components against deactivation and encapsulating substrates within the cavity, resulting in yields comparable to or even surpassing those of their molecular counterparts. This work thus provides a new strategy that combines metal templating and nontemplating approaches to design new types of interlocked assemblies with intriguing architectures and properties.

Synthesis of Topological Gels by Penetrating Polymerization Using a Molecular Net

AbstractTopological gels possess structures that are cross‐linked only via physical constraints; ideally, no attractive intermolecular interactions act between their components, which yields interesting physical properties. However, most reported previous topological gels were synthesized based on supramolecular interlocked structures such as polyrotaxane, for which attractive intermolecular interactions are essential. Here, we synthesize a water‐soluble “molecular net” (MN) with a large molecular weight and three‐dimensional network structure using poly(ethylene glycol). When a water‐soluble monomer (N‐isopropylacrylamide) is polymerized in the presence of the MNs, the extending polymer chains penetrates the MNs to form an ideal topological MN gel with no specific attractive interactions between its components. The MN gels show unique physical properties as well a significantly high degree of swelling and high extensibility due to slipping of the physical cross‐linking. We postulate this method to yield a new paradigm in gel science with unprecedented physical properties.

Multifunction composite phase change material with inorganic flame retardant and organic form stability for improving battery thermal safety

<p>Phase change materials (PCMs) with superior cooling capacity and temperature equalization have great potential to mitigate thermal accumulation, benefiting the safety of electric vehicles (EVs) drivers. Although the composite phase change materials (CPCMs) with organic form stable addition can prevent leakage, they are still restricted in battery module due to easy flammable performance. Another challenge is that the inorganic flame retardants always distribute unevenly in organic CPCMs. Herein, to overcome the drawback of uneven additives dispersion within paraffin, we proposed a novel CPCM with inorganic flame-retardant and organic form stable material, composed of Paraffin/Styrene-Ethylene-Butylene-Styrene/AmmoniumPolyphosphate/Silicon dioxide/Carbon micro-nano aggregates (PS/APP/SiO<sub>2</sub>@C). The prepared material exhibits anti-leakage property with 99.5 % mass retention after heating for 10 h at 70 ��C, and the smoke generation rate is only 0.01 m<sup>2</sup>��s<sup>-1</sup>. The total heat releasing time is extended to 700 s, three times longer than that of PS. As for battery thermal management system, the maximum temperature and the temperature difference of battery module with PS/APP are 81.2 ��C and 5.6 ��C at 5 C discharge rate, respectively. In comparison, the maximum temperature and maximum temperature difference can be controlled to 58.5 ��C and 1.5 ��C, respectively, without heat accumulation during the twenty cycles. It indicates that the temperature is lower than the critical one to avoid thermal runaway of EVs. Therefore, this study presents CPCMs as an advanced thermal management approach that can enhance the thermal safety of battery packs, resulting in a significant impact on millions of drivers of EVs around the world.</p>

Core-Sheath Heterogeneous Interlocked Conductive Fiber Enables Smart Textile for Personalized Healthcare and Thermal Management.

Whereas thermal comfort and healthcare management during long-term wear are essentially required for wearable system, simultaneously achieving them remains challenge. Herein, a highly comfortable and breathable smart textile for personal healthcare and thermal management is developed, via assembling stimuli-responsive core-sheath dual network that silver nanowires(AgNWs) core interlocked graphene sheath induced by MXene. Small MXene nanosheets with abundant groups is proposed as a novel "dispersant" to graphene according to "like dissolves like" theory, while simultaneously acting as "cross-linker" between AgNWs and graphene networks by filling the voids between them. The core-sheath heterogeneous interlocked conductive fiber induced by MXene "cross-linking" exhibits a reliable response to various mechanical/electrical/light stimuli, even under large mechanical deformations(100%). The core-sheath conductive fiber-enabled smart textile can adapt to movements of human body seamlessly, and convert these mechanical deformations into character signals for accurate healthcare monitoring with rapid response(440ms). Moreover, smart textile with excellent Joule heating and photothermal effect exhibits instant thermal energy harvesting/storage during the stimuli-response process, which can be developed as self-powered thermal management and dynamic camouflage when integrated with phase change and thermochromic layer. The smart fibers/textiles with core-sheath heterogeneous interlocked structures hold great promise in personalized healthcare and thermal management.

Supramolecularly Dimeric Assemble of Planar Cu13 Clusters Controlled by the Length of Spacers of Diphosphine.

The controlled formation of dimeric clusters is challenging. Three copper(I) clusters, labeled as {Cu13[o-Ph(C≡C)2]6(L)4}(ClO4), were synthesized by using three different ligands, including 1,4-bis(diphenylphosphino)butane (dppb), 1,5-bis(diphenylphosphino)pentane (dpppe), and bis(diphenylphosphino)hexane (dpph). By increasing the flexibility of alkyl spacers in the diphosphine ligands, the relative positions of the phenyl rings could be optimized to achieve efficient packing with maximized intercluster interactions. In the crystal structures, cluster 1 with dppb ligands did not display interlocked structures. In contrast, cluster 2 with dpppe ligands formed supramolecularly interlocked polymers through weak π-π interactions and C-H···π interactions, while cluster 3 employing dpph ligands formed supramolecularly interlocked dimers with strong π-π interactions and C-H···π interactions. The supramolecular dimer of 3 was also evidenced by analyses through electrospray ionization mass spectrometry and transmission electron microscopy. Density functional theory calculation was used to understand the electronic structure and transitions. Supramolecularly interlocked polymers/dimers with rigid structures exhibited higher quantum efficiency. The solution of these clusters demonstrated remarkable aggregation-induced emission enhancements. This study presents unique examples of planar luminescent copper clusters, featuring the first serial dialkynyl-protected cluster. It underlines the importance of ligand flexibility in creating supramolecular cluster dimers.

Waterproof and Flexible Aquatic Tactile Sensor with Interlocked Ripple Structures for Broad Range Force Sensing

AbstractUnderwater perception of a broad range of force holds great importance in aquatic explorative activities, while flexible tactile sensors face technical challenges to realize. This paper presents a novel flexible aquatic tactile sensor based on waterproof graphene (GR)/carbon nanotube (CNT)/Polydimethylsiloxane (PDMS) composites. The prepared GR/CNT/PDMS composites possess excellent hydrophobic and electromechanical properties with a water contact angle over 134° and an ultrahigh gauge factor of 2296, making them an ideal piezoresistive sensing material for underwater broad‐range force sensing. The proposed tactile sensor has 3 × 3 sensing units and uses dual interlocked water‐ripple structures to improve its sensitivity and force detection range. The fabricated tactile sensor is characterized by two distinct sensitivities: a high sensitivity of 0.0338 kPa−1 at 0.062–150 kPa and a low sensitivity of 0.00357 kPa−1 at 150–450 kPa. Further, the sensor exhibited excellent resistance response, fast dynamic recovery, and both mechanical and electrical stability in aquatic environments. Then, the aquatic tactile sensor is worn on the palm of the human hand to detect the distribution and variation of contact forces when grasping objects with different shapes and hardness, demonstrating the potential underwater applications of the developed aquatic tactile sensor for broad‐range force sensing.

Preparation of Al2O3 ceramics with long-range inter-locked platelet structures possessing high porosity and excellent mechanical strength

Porous Al2O3 ceramics with long-range inter-locked platelet structures were prepared by a facile gel-casting method using cryolite and β-SiC as additives. An extremely high mass transfer efficiency for the construction of the long-range inter-locked platelet structures was provided by NaAl11O17 and NaAlSiO4, which are generated through chemical reactions of additives during sintering. Moreover, the effect of additive content on the evolution of the inter-locked platelet structures was discussed, while the relationship between the inter-locked platelet structures and the compressive strength and thermal conductivity of porous Al2O3 ceramics was also investigated. The sample with 1.5 wt% β-SiC and 15.0 wt% cryolite had a long-range inter-locked platelet structure, which exhibited excellent compressive strength (60.5 MPa) while maintaining high porosity (53.4 %). Interestingly, the long-range inter-locked platelet structures were capable of rapid heat transfer, while the localized inter-locked platelet structures had a great thermal insulation effect.

Active-metal template clipping synthesis of novel [2]rotaxanes.

Mechanically interlocked molecules (MIMs) have been important synthetic targets in supramolecular chemistry due to their beautiful structures and intriguing properties. We present herein a new synthetic strategy to access [2]rotaxanes, namely active-metal template clipping. We discuss the design of the target [2]rotaxanes, synthesis and characterization of the axle, macrocycle precursors and macrocycles as well as preparation of the final [2]rotaxanes by active template copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) as key step of the synthesis. HRMS and NMR experiments have been performed to confirm the formation of the interlocked structures.

Boron-Nitrogen Lewis Pairs in the Assembly of Supramolecular Macrocycles, Molecular Cages, Polymers, and 3D Materials.

Covering an exceptionally wide range of bond strengths, the dynamic nature and facile tunability of dative B-N bonds is highly attractive when it comes to the assembly of supramolecular polymers and materials. This Minireview offers an overview of advances in the development of functional materials where Lewis pairs (LPs) play a key role in their assembly and critically influence their properties. Specifically, we describe the reversible assembly of linear polymers with interesting optical, electronic and catalytic properties, discrete macrocycles and molecular cages that take up diverse guest molecules and undergo structural changes triggered by external stimuli, covalent organic frameworks (COFs) with intriguing interlocked structures that can embed and separate gases such as CO2 and acetylene, and soft polymer networks that serve as recyclable, self-healing, and responsive thermosets, gels and elastomeric materials.

Boron‐Nitrogen Lewis Pairs in the Assembly of Supramolecular Macrocycles, Molecular Cages, Polymers, and 3D Materials

AbstractCovering an exceptionally wide range of bond strengths, the dynamic nature and facile tunability of dative B−N bonds is highly attractive when it comes to the assembly of supramolecular polymers and materials. This Minireview offers an overview of advances in the development of functional materials where Lewis pairs (LPs) play a key role in their assembly and critically influence their properties. Specifically, we describe the reversible assembly of linear polymers with interesting optical, electronic and catalytic properties, discrete macrocycles and molecular cages that take up diverse guest molecules and undergo structural changes triggered by external stimuli, covalent organic frameworks (COFs) with intriguing interlocked structures that can embed and separate gases such as CO2 and acetylene, and soft polymer networks that serve as recyclable, self‐healing, and responsive thermosets, gels and elastomeric materials.

The Deflection Limit of Slab-Like Topologically Interlocked Structures

Abstract Topologically interlocked structures (TIS) are structural assemblies that achieve stability and carrying capacity through the geometric arrangement of interlocking blocks, relying solely on contact and friction forces for load transfer. Unlike beam-like TIS, whose deflection never exceeds the height of the blocks, the deflection of slab-like TIS often does. Yet, the upper limit of deflection of slab-like TIS, a key parameter defining their loading energy capacity, remains unexplored. Here, we establish a theoretical upper bound for the deflection capacity of slab-like TIS and outline a systematic design strategy to approach this upper bound. This strategy is based on engineering the contact interfaces such that the non-central blocks are more engaged in the structural response, leading to a more global and holistic deformation mode with higher deflections. We demonstrate the application of this strategy in a numerical case study on a typical slab-like TIS and show that it leads to an increase in deflection by a factor of 3.5, yielding a value closer to the upper bound than previously reported in the literature. We find that the resulting deflection mode engages all the blocks equally, avoids localized sliding modes, and resembles that of monolithic equivalents. Lastly, we show that the strategy not only maximizes TIS’ deflection capacity but also their loading energy capacity.

Failure of topologically interlocked structures — a Level-Set-DEM approach

Topological Interlocking Structures (TIS) are assemblies of interlocking building blocks that hold together solely through contact and friction at the block interfaces and thus do not require any connective elements. This salient feature makes them highly energy-absorbent, resistant to crack propagation, geometrically versatile, and reusable. It also gives rise to failure mechanisms that, differently from ordinary structures, are governed by multiple contact interactions between blocks and frictional slip at their interfaces. Commonly-used modeling tools for structural analysis struggle to capture and quantify these unusual failure mechanisms. Here, we propose a different approach that is well-suited for modeling the complex failure of slab-like TIS. It is based on the Level-Set-Discrete-Element-Method, which was originally developed for granular mechanics applications. After introducing the basic assumptions and theoretical concepts underlying our model, we show that it accurately captures the slip-governed failure of slab-like TIS panels as observed in the literature, that it can closely estimate the force–displacement curves, and that it is can be used to explore important features governing the structural mechanics of TIS. The theoretical foundation, together with the results of this study, provide a proof-of-concept for our new approach and point to its potential to improve our ability to model and understand the behavior of interlocked structural forms.

Diastereoselective Rotaxane Synthesis with Pillar[5]arenes via Co-crystallization and Solid-State Mechanochemical Processes.

Chiral rotaxanes have attracted much attention in recent decades for their unique chirality based on their interlocked structures. Thus, selective synthesis methods of chiral rotaxanes have been developed. The introduction of substituents with chiral centers to produce diastereomers is a powerful strategy for the construction of chiral rotaxanes. However, in case of a small energy difference between the diastereomers, diastereoselective synthesis is extremely difficult. Herein, we report a new diastereoselective rotaxane synthesis method using solid-phase diastereoselective [3]pseudorotaxane formation and mechanochemical solid-phase end-capping reactions of the [3]pseudorotaxanes. By co-crystallization of stereodynamic planar chiral pillar[5]arene with stereogenic carbons at both rims and axles with suitable end groups and lengths, the [3]pseudorotaxane with a high diastereomeric excess (ca. 92% de) was generated in the solid state because of higher effective molarity with aid by packing effects and significant energy differences between [3]pseudorotaxane diastereomers. In contrast, the de of the pillar[5]arene was low in solution (ca. 10% de) because of a small energy difference between diastereomers. Subsequent end-capping reactions of the polycrystalline [3]pseudorotaxane with high de in solvent-free conditions successfully yielded rotaxanes while maintaining the high de generated by the co-crystallization.