Wavy Chains Research Articles

Experimental study and mechanism analysis on the effect of pre-curing time on the microstructure and mechanical properties of magnetorheological elastomers under compression

The effects of the pre-curing time before exposing the carbonyl iron particles (CIPs) filled liquid polydimethylsiloxane (PDMS) mixture to a preparatory magnetic field on the magnetorheological (MR) effects of the magnetorheological elastomers (MREs) were experimentally and theoretically investigated. The anisotropic MRE samples with different pre-curing time were firstly fabricated and their compressive MR effects were tested. The results showed that the longer pre-curing time induces the shorter and more irregular particle chains formed in the MREs, and the sample pre-cured for 20 min showed the maximum MR effect. Then based on the rheological characterization, a rheological model was proposed to predict the rheological property evolution of CIPs/PDMS mixture with respect to the pre-curing time, and a modified three-dimensional (3D) particle dynamics (PD) model was developed to simulate the particle structure evolution in the MRE mixtures under a preparatory magnetic field. The simulation results showed that short chains were first formed owing to the magnetic attraction between the adjacent particles. Then these short chains approached each other to form long chains and even thick chain-like clusters. The later process can be restrained by increasing the pre-curing time, thus more short and incompact particle chains are formed in the MREs. Lastly, simplified microstructure models representing the wavy chains were used to explore the effect of particle arrangement on the MR effect of the MREs under compression. It is found that the wavy chains with incompactly packed particles are beneficial for improving the MR effect owing to the strong transverse magnetic attraction between the neighboring particles. This work demonstrates that PD simulation is an efficiency method to predict the particle arrangement evolution in the MRE mixture, and the possibility to tailoring the microstructures of the MREs by adjusting the viscosity of MRE mixtures to improve their MR effects, while keeping a high zero-field modulus simultaneously.

Exploring the physicochemical properties of a new mixed halide 1D hybrid material Zn(C2H8N2)Br1.41Cl0.59 with a non-centrosymmetric structure: Promising material for nonlinear applications

Colorless crystals of a new mixed halide hybrid material, Zn(C2H8N2)Br1.41Cl0.59, were synthesized by the slow evaporation method at room temperature. The crystal structure, thermal behavior, and optical analysis were analyzed to characterize this complex. The crystal structure study revealed that this compound adopts the orthorhombic system and crystallizes in the non-centrosymmetric space group Ima2. Its one-dimensional structure is built from infinite wavy chains of [Zn(C2H8N2)Br1.41Cl0.59]n propagating along the crystallographic a-axis, which are interconnected through NH···Br/Cl hydrogen bonds. Thermogravimetric analysis indicated that this complex remains stable up 251 °C, decomposing in a single step to yield zinc oxide (ZnO) as final product. Differential scanning calorimetry (DSC) revealed an endothermic peak at 195 °C, indicating that the title compound undergoes a phase transition at this temperature. Additionally, the material's suitability for optical application was assessed through UV–Visible absorption and non-linear optical (NLO) techniques. The determined band gap energy of 4.5 eV suggests that this new complex can be classified as a semiconductor material closely resembling an insulator. Furthermore, the second harmonic generation (SHG) efficiency of the grown crystal was analyzed using the Kurtz-Perry powder technique. The IR and Raman spectra confirm the results obtained from X-ray single-crystal structural analyses.

Synthesis, crystal structure, characterization, effective photocurrent response and photodegradation of a silver(I) diphosphine 3D supramolecular structure

A new three-dimensional (3D) supramolecular compound, [Ag(dppe)(CF3COO)]n (1), was prepared by using Ag(I) as the silver source and dppe as the organic ligand through the self-assembly approach. The bridging dppe ligand makes compound 1 appear as a one-dimensional (1D) wavy chain consolidated by the intramolecular hydrogen bonds. Two adjacent 1D chains are expanded to a two-dimensional (2D) layer passing through the intermolecular CH···π interaction between the dppe ligands, and the 2D layers further weave into a 3D supramolecular structure via another intermolecular CH···π interactions between the dppe ligands. The precise structure of 1 was determined by single crystal X-ray diffractometer (SCXRD), and it was well-characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TG) and differential thermogravimetry analysis (DTG), and UV–vis diffuse reflectance spectrum. In addition, the photocurrent response, electrochemistry characteristic and photodegradation of 1 were investigated. The degradation efficiency (82 %) of 1 as catalyst to degrade methylene blue (MB) was significantly higher than that without catalyst.

An Indium metal-organic framework with a two-fold-interpenetrating structure for the efficient conversion of CO2

An Indium metal-organic framework {[H3O]2[In2(BDC)3(ox)]·2DMA} based on 1,4-dicarboxybenzene (H2BDC) and oxalic acid (H2ox) has been constructed, exhibiting a two-fold-interpenetrating 3D structure with good stability. Each In3+ ion is eight-coordinated by six carboxylate oxygen atoms from three BDC2− ligands and two carboxylate oxygen atoms of one oxalate anion. The ligands BDC2− are joined by In3+ ions to construct a 1D wavy chain, while ligands BDC2− and ox2− are connected alternatively by In3+ ions to form another wavy chain. These two types of chains are interwoven into a three-dimensional structure. It has been explored as an effectively heterogeneous catalyst for the synthesis of cyclic carbonates by CO2 fixation. Under the reaction condition of 10 ​mg catalyst, 70 ​°C, atmospheric pressure over 24 ​h, the yield of epichlorohydrin carbonate can reach 92.0% with the turnover number (TON) value of 2300.

On-Surface Synthesis of Self-Assembled Covalently Linked Wavy Chains with Site-Selective Conformational Switching.

Conformational arrangements in polymers on surfaces determine the overall shape as well as the potential properties. It is generally believed that conformational diversity leads to uncontrollable or disordered structures in on-surface synthesis. However, in this study, we obtain two well-ordered self-assembled covalently linked wavy chains with site-selective conformational switching via the Ullmann reaction of 1,2-bis(3-bromophenyl)ethane with multiple conformations on Ag(111). Two kinds of wavy chains exhibit distinct conformational arrangements, where chain I contains one repeating unit conformation of -cis-trans1-cis-trans1-cis-cis-trans1-, while the adjacent parallel parts in wavy chain II have two different conformational arrangements of -cis-cis-trans1- and -cis-cis-trans2-. Wavy chains coassemble with dissociated bromine atoms, suggesting that the Br···H-C interactions between Br atoms and molecular chains are crucial for the construction of ordered wavy chains. High-resolution scanning tunneling microscopy is employed to reveal the surface reaction process at the molecular scale. In depth growth mechanism analysis combined with density functional theory calculations unveils that the substrate also plays an important role in the fabrication of well-ordered wavy chains. The present work extends the surface reaction of conformational flexible precursors.

The pseudocapacitance and sensing materials constructed by Dawson/basket-like phosphomolybdate

Three phosphomolybdate hybrid derivatives, (H2bib)2.5{HP2Mo18O62}·2H2O (1), (H2bib){Sr⊂H4P6Mo18O73}·6H2O (2), (H2bib)3[{Co(H2O)2}{Sr⊂P6Mo16ⅥMo2Ⅴ O73}]·6H2O (3) (bib ​= ​1,4-Bis(imidazolyl)butane) were built by bib inducer via in situ hydrothermal reaction and fully characterized. Compounds 1 and 2 are bib modified Dawson and basket-like hybrids with complex topologies, respectively. In structure of 3, {P6Mo18O73} polyanions arranged in ABAB manner are alternately bridged by {Co(H2O)2} unit to yield an extended wavy chain, which was expanded into supramolecular sheets and infinite 3-D meshwork. The irregularly shaped tunnels are produced in the spatial structure of 3. The electrochemical tests show compound 3 presents enhance specific capacitance (797.8 ​F·g−1at 3 A/g), cycle efficiency (96.5% after the 5000th cycle), electrical conductivity, and catalytic activity than those of compounds 1 and 2 due to its structure advantages. Moreover, 3-GCE exhibits electrochemical responses to AA at potential of 0.3 ​V with the lower detection line of 0.16 ​μM, the wider linear range of 4.00 μM–4.72 ​mM, merit selectivity and reproducibility. The merit capacitive and sensing properties of 3 are attributed to introduction of transition metal Co, which not only provides additional redox active sites, but also bridges the basket clusters to form ordered tunnels that providing the necessary paths for ion or electron transmission.

Acid/base regulated syntheses of different 1D coordination chains for selective mercury removal from aqueous solution

Two calixarene-based coordination chains were obtained solvothermally with a bridging ligand, 5-(4-Pyridyl)-1H-1,2,4-triazole-3-thiol (L) upon the adding of triethylamine or concentrated HCl, namely, [(C2H5)3NH]2[Co4(TC4A)(L)2(SO4)2]·5(CH3OH) (CIAC-256) and [Co8(TC4A)2(L)2(SO4)3 (CH3OH)6]·2(C3H7NO)·3(CH3OH) (CIAC-257; H4TC4A ​= ​p-tert-butylthiacalix [4]arene). Both compounds are featured with some 1D wavy (or zigzag) chains. In CIAC-256, the shuttlecock-like Co4-TC4A secondary building units (SBUs) are interconnected by the L ligands into the chains while in CIAC-257, the SBUs are bridged by both the L ligands and the sulfonate anions. Both compounds are effective adsorbents for the selective removal of Hg(II) from the aqueous solution and the maximum adsorption capacities for Hg(II) are 411 ​mg/g for CIAC-256 and 307 ​mg/g for CIAC-257, respectively. Magnetic measurements suggest that all the cobalt (II) centers exhibit antiferromagnetic interactions.

Soft fibers with magnetoelasticity for wearable electronics

Magnetoelastic effect characterizes the change of materials’ magnetic properties under mechanical deformation, which is conventionally observed in some rigid metals or metal alloys. Here we show magnetoelastic effect can also exist in 1D soft fibers with stronger magnetomechanical coupling than that in traditional rigid counterparts. This effect is explained by a wavy chain model based on the magnetic dipole-dipole interaction and demagnetizing factor. To facilitate practical applications, we further invented a textile magnetoelastic generator (MEG), weaving the 1D soft fibers with conductive yarns to couple the observed magnetoelastic effect with magnetic induction, which paves a new way for biomechanical-to-electrical energy conversion with short-circuit current density of 0.63 mA cm−2, internal impedance of 180 Ω, and intrinsic waterproofness. Textile MEG was demonstrated to convert the arterial pulse into electrical signals with a low detection limit of 0.05 kPa, even with heavy perspiration or in underwater situations without encapsulations.

Discovering giant magnetoelasticity in soft matter for electronic textiles

We discovered a giant magnetoelasticity in soft matter with up to 5-fold enhancement of magnetomechanical coupling factors compared to that of rigid metal alloys without an externally applied magnetic field. A wavy chain analytical model based on the magnetic dipole-dipole interaction and demagnetizing field was established, fitting well to the experimental observation. To explore its potentials in electronic textiles, we coupled it with magnetic induction to invent a textile magnetoelastic generator (MEG), a new working mechanism for biomechanical energy conversion, featuring an intrinsic waterproofness, an ultralow internal impedance of approximately 20 Ω, and a high short-circuit current density of 1.37 mA/cm2, which is about four orders of magnitude higher than that of other textile generator counterparts. Meanwhile, assisted by machine learning, the textile MEG could continuously monitor the respiratory activities on heavily perspiring skin without any encapsulation, allowing a timely diagnosis of the respiration abnormalities in a self-powered manner. We foresee that this discovery can be extended to wide-range soft-matter systems, emerging as a compelling approach to develop electronic textiles for energy, sensing, and therapeutic applications.

Giant magnetoelastic effect in soft systems for bioelectronics

The magnetoelastic effect-the variation of the magnetic properties of a material under mechanical stress-is usually observed in rigid alloys, whose mechanical modulus is significantly different from that of human tissues, thus limiting their use in bioelectronics applications. Here, we observed a giant magnetoelastic effect in a soft system based on micromagnets dispersed in a silicone matrix, reaching a magnetomechanical coupling factor indicating up to four times more enhancement than in rigid counterparts. The results are interpreted using a wavy chain model, showing how mechanical stress changes the micromagnets' spacing and dipole alignment, thus altering the magnetic field generated by the composite. Combined with liquid-metal coils patterned on polydimethylsiloxane working as a magnetic induction layer, the soft magnetoelastic composite is used for stretchable and water-resistant magnetoelastic generators adhering conformably to human skin. Such devices can be used as wearable or implantable power generators and biomedical sensors, opening alternative avenues for human-body-centred applications.

Heteronuclear Dirhodium-Gold Anionic Complexes: Polymeric Chains and Discrete Units.

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh2(μ–O2CCH2OMe)4(THF)2] (1) and [Rh2(μ–O2CC6H4–p–CMe3)4(OH2)2] (2) by metathesis reaction of [Rh2(μ–O2CMe)4] with the corresponding ligand acting also as the reaction solvent. The reaction of the corresponding tetracarboxylato precursor, [Rh2(μ–O2CR)4], with PPh4[Au(CN)2] at room temperature, yielded the one-dimensional polymers (PPh4)n[Rh2(μ–O2CR)4Au(CN)2]n (R = Me (3), CH2OMe (4), CH2OEt (5)) and the non-polymeric compounds (PPh4)2{Rh2(μ–O2CR)4[Au(CN)2]2} (R = CMe3 (6), C6H4–p–CMe3 (7)). The structural characterization of 1, 3·2CH2Cl2, 4·3CH2Cl2, 5, 6, and 7·2OCMe2 is also provided with a detailed description of their crystal structures and intermolecular interactions. The polymeric compounds 3·2CH2Cl2, 4·3CH2Cl2, and 5 show wavy chains with Rh–Au–Rh and Rh–N–C angles in the ranges 177.18°–178.69° and 163.0°–170.4°, respectively. A comparative study with related rhodium-silver complexes previously reported indicates no significant influence of the gold or silver atoms in the solid-state arrangement of these kinds of complexes.

Two 1D chain complexes based on N,N′-bis(4-pyridylmethyl)pyromellitic diimide and fluorescence azide sensing

Two complexes, {[Hg(4-pmpmd)Br2]•CHCl3)} n (1), [Cd(4-pmpmd) (CF3SO3)2] n (2) were synthesized (4-pmpmd: N,N′-bis(4-pyridylmethyl)pyromellitic diimide). Both complexes were characterized by IR spectroscopy, powder X-ray diffraction, elemental analyses, single crystal X-ray diffraction, and thermogravimetric analyses. Complex 1 features a typical 1D zigzag chain structure with the adjacent chains intertwined via hydrogen bonds, while complex 2 shows 1D parallel-packed wavy chains structure through π···π stacking interactions. The weak interactions of pyromellitic diimide and anions effect on 1D chain supramolecular structural diversity. Taking advantage of azide anion strong binding affinities, complex 2 could be developed as fluorescence sensor for azide anion.

Two new coordination polymers constructed by two viologen-derived ligands: Structure and photochromism

Two new 1D Zn(II) and Mn(II) coordination polymers, namely, [ZnL1(H2O)Cl]·[(Cl)·2H2O] (CP-1), [Mn(L2)2(N3)2]·3H2O (CP-2) ([H2L1]Cl2 = [1,1′-bis(3-carboxylatobenzyl)-4,4′-bipyridinium] dichloride and [H2L2]Cl2 = [1,1′-bis(4-carboxylatobenzyl)-4,4′-bipyridinium] dichloride) have been synthesized successfully by the self-assembly of Zn(II) and Mn(II), N3ˉ and two different viologen ligands, respectively. CP-1 shows a zigzag chain structure which the Zn(II) ions are linked by L1 ligands, while CP-2 shows a wavy chain structure which the Mn(II) ions are linked by L2 ligands. Both of them showed typical electrochemical redox properties and photochromic properties, which involved the radicals formation via photoinduced electron transfer. The mechanism of photochromism of two compounds has been demonstrated by UV–vis absorption characterization analysis, electron paramagnetic resonance spectroscopy (EPR), X-ray photoelectron spectra (XPS) and structural analysis.

Syntheses, structures and properties of three novel Cu(Ⅱ) coordination compounds based on 4,4′-oxybisbenzoic acid

Three Cu(Ⅱ) coordination compounds (CCs) with 4,4′-oxybisbenzoic acid (H2OBBA), {Cu3(OBBA)2(NH3)4}n (1), {Cu(OBBA)0.5(NH3)}n (2), {Cu2(OBBA) (NH3) (OH)}n (3) were synthesized under the ammoniacal condition in mixed solvents and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis and Fourier transform infrared spectra. Crystallographic studies have shown that, CC 1 is a 1D wavy chain structure, while the intermolecular connection of hydrogen bonds made it a 2D layered structure; CC 2 is a 2D layered structure composed of a 1D wavy chain structure and the O–H⋯N hydrogen bonds of R (2)2 (12) hydrogen bond motifs; CC 3 forms a 3D supramolecular framework through OH−, OBBA ligand and hydrogen bonds, in which, OBBA ligand has two cyclic patterns: C–OM―O and C–O―M, O⋯H–N. It may be concluded that OBBA ligands and hydrogen bonds play important role in the formation of multiple architectures. The photoluminescence and thermal behavior were also studied.

Anion-directed assembly of three cationic silver(I) coordination polymers with bis(imidazolyl)-based linker: Structural characterization and anion exchange study

Three cationic silver(I) coordination polymers, namely {[Ag2(μ-bib)3](SO3CF3)2·(CH3CN)}n (1), {[Ag(μ-bib)](NO3)·(H2O)}n (2), and {[Ag(μ-bib)]BF4}n (3), have been prepared using flexible bis(imidazolyl)butane (bib) ligand and silver salts of different anions. All compounds are characterized by FT-IR, PXRD, elemental analysis, and single-crystal X-ray diffraction. Compound 1, containing triflate (SO3CF3−) anions, exhibits a two dimensional 63-hcb network with an amazing ABCDEF packing mode of the single hexagonal layers. Compound 2, containing nitrate ions, forms a simple one dimensional wavy chain, while compound 3 with BF4− anions, shows a double helix DNA-shaped structure stabilized by Ag⋯Ag interactions between the two strands. The anions in the structures 1–3 are non-coordinating and participate in weak H-bonding, while imidazolyl rings are involved in π⋯π stacking interactions. Anion exchange experiments in aqueous solution, monitored by FT-IR and PXRD analyses, reveal interesting structural transformations.

Synthesis, Crystal Structure, and Thermal Expansion of Sodium Barium Zirconium Phosphate–Sulfate

The phosphate–sulfate synthesis approach preventing the elimination of sulfur in the process of synthesis has been tested for NaBa6Zr(PO4)5SO4 as an example. The phase formation and thermal stability of phosphate–sulfate have been studied by X-ray diffraction and DTA-TG. The NaBa6Zr(PO4)5SO4 structure (space group I$$\overline 4 $$3d, a = 10.5449(3) A, V = 1172.54(5) A3, Z = 4) allied to the eulytite mineral has been refined by the Rietveld method. The structure is formed by wavy chains of edge-sharing (Na,Ba,Zr)O6-octahedra and (P,S)O4-tetrahedra sharing apices with the octahedra. Using thermal X-ray diffraction, it has been established that phosphate–sulfate is a strongly expanding material (αа = αb = αc = 13.3 × 10–6°C–1).

Crystal structure of 2,4,6-tri-methyl-benzoic anhydride.

The title compound, C20H22O3, was formed in the reaction between 2,4,6-tri-methyl-benzoic acid and N,N-diiso-propyl-ethyl-amine in the presence of 1,3-di-chloro-1,3-bis-(di-methyl-amino)-propenium hydrogen dichloride, and was recrystallized from diethyl ether solution. It is the first exclusively alkyl-substituted benzoic anhydride to have been structurally characterized. The asymmetric unit consists of a half mol-ecule, the other half of which is generated by twofold rotation symmetry; the dihedral angle between the symmetry-related aromatic rings is 54.97 (3)°. The geometric parameters of the aromatic ring are typical of those for 2,4,6-tri-methyl-phenyl substituted groups. The C=O and C-O bond lengths are 1.1934 (12) and 1.3958 (11) Å, respectively, and the angle between these three atoms (O=C-O) is 121.24 (9)°. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds and C-H⋯π inter-actions. The packing features wavy chains that extend parallel to [001].

A series of 1D-to-3D coordination polymers from an unsymmetrical tetracarboxylic acid and various N-donor ligands: Syntheses, structures and photoluminescence properties

Five new coordination polymers (CPs) based on unsymmetrical tetracarboxylic acid and varied auxiliary N-donor ligands, [Ln(α-Hbptc)(H2O)4]·H2O (Ln=Eu, 1; Tb, 2), [Cu2(α-bptc)(bipy)(H2O)4]·H2O (3), [Cd2(α-bptc)(phen)2(H2O)2]·H2O (4), [Cd2(α-bptc)(bpee)0.5(H2O)4]·3H2O (5), [α-H4bptc=2,3,3′,4′-biphenyl tetracarboxylic acid, bipy=4,4′-bipyridine, bpee=1,2-bis(4-pyridyl)ethylene, phen=1,10-phenanthroline] have been hydrothermally synthesized. Compounds 1 and 2 are isomorphous and show a 2D 63-hcb network in the absence of any N-donor ligand. Compound 3 is a 1D “loop” chain structure with alternating the 14- and 40-membered metallacycles in the presence of bipy. Compound 4 features 1D wavy chain by using phen instead of bipy. The coordination structures of 1–4 are further extended into 3D supramolecular frameworks through different hydrogen bonds. Compound 5 possesses a 3D pillar-layer framework built via the 2D layers with opposite handedness and bpee. The solid state photoluminescence properties of compounds 1, 2, 4, and 5 were investigated. Compounds 1 and 2 exhibit characteristic Eu(III) and Tb(III) emissions in the red and green light regions, respectively. Compounds 4 and 5 display strong fluorescent emissions at 404 and 380nm in solid state at room temperature, respectively.

A numerical study on magnetostrictive phenomena in magnetorheological elastomers

Herein, we present an investigation on magnetostrictive phenomena in magnetorheological elastomers. By using a continuum approach, constitutive as well as geometric properties on the microscale are taken into account in order to predict the effective behavior of these composites by means of a computational homogenization. Thus, the magnetic and mechanical fields are resolved explicitly without the simplifying assumption of dipoles. In the present work, a modeling strategy which accounts for elastic constituents and a nonlinear magnetization behavior of the particles is pursued. In order to provide a better understanding of fundamental deformation mechanisms, idealized lattices as well as compact and wavy chains are considered within a first study. Our results confirm assumptions stated in the literature according to which macroscopic magnetostriction can be ascribed to microscopic particle movements that result in an improved microstructure. The simulations that are performed for the subsequent investigations on random microstructures with different particle-volume fractions are evaluated statistically to ensure validity of our findings. They reveal anisotropic as well as isotropic macroscopic behavior for structured and unstructured particle distributions, respectively. In view of the macroscopic magnetostriction, all the results presented in this contribution are in good agreement with current experimental and theoretical findings.

Triple Helical Molecular Braid and Parallel Packed Wavy Chain-Based Supramolecular Organic Frameworks with Conformation- and Packing-Dependent Luminescent Properties

Two three-dimensional supramolecular organic frameworks, [(H2bpdc)0.5(bipy)0.5] (1) and [(H3dpob)(bipy)·3H2O] (2), have been successfully constructed and structurally characterized (H2bpdc = 2,2′-biphenyldicarboxylic acid; H3dpob = 3-(2′,3′-dicarboxylphenoxy)benzonic acid; bipy = 4,4′-bipydine). 1 is driven by C–H···π hydrogen-bonded packing to three dimension. 2 origins form parallel-packed wavy chains and show π–π stacking-directed structure. After the SOFs are formed via weak noncovalent interaction, 1 and 2 show an enhancement in thermostability. The different conformations of bipy induced by weak noncovalent interactions are responsible for the huge dissimilarity of structural and luminescence behavior between them. Under the excitation of 365 nm ultraviolet light, 1 and 2 show stronger blue-white and green-white luminescent emissions in the solid state, respectively. In comparison with 2, supramolecular organic framework 1 shows superior performance in aggregation-induced emission (AIE) activity, wh...