Flexible Bis Research Articles

Novel Bis(4-aminophenoxy) Benzene-Based Aramid Copolymers with Enhanced Solution Processability.

Aramid copolymers have garnered significant interest due to their potential applications in extreme environments such as the aerospace, defense, and automotive industries. Recent developments in aramid copolymers have moved beyond their traditional use in high-strength, high-temperature resistant fibers. There is now a demand for new polymers that can easily be processed into thin films for applications such as electrical insulation films and membranes, utilizing the inherent properties of aramid copolymers. In this work, we demonstrate two novel aramid copolymers that are capable of polymerizing in polar organic solvents with a high degree of polymerization, achieved by incorporating flexible bis(4-aminophenoxy) benzene moieties into the chain backbone. The synthesized MBAB-aramid and PBAB-aramid have enabled the fabrication of exceptionally thin, clear films, with an average molecular weight exceeding 150 kDa and a thickness ranging from 3 to 10 μm. The dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) reveal that the thin films of MBAB-aramid and PBAB-aramid exhibited glass transition temperatures of 270.1 °C and 292.7 °C, respectively, and thermal decomposition temperatures of 449.6 °C and 465.5 °C, respectively. The mechanical tensile analysis of the 5 μm thick films confirmed that the tensile strengths, with elongation at break, are 107.1 MPa (50.7%) for MBAB-aramid and 113.5 MPa (58.4%) for PBAB-aramid, respectively. The thermal and mechanical properties consistently differ between the two polymers, which is attributed to variations in the linearity of the polymer structures and the resulting differences in the density of intermolecular hydrogen bonding and pi-pi interactions. The resulting high-strength, ultra-thin aramid materials offer numerous potential applications in thin films, membranes, and functional coatings across various industries.

Metal Ion and Metal‐to‐Ligand Ratio Regulated Construction of Cu(II) and Co(II) Coordination Polymers as Efficient Catalysts for Ring‐Opening Polymerization of L‐Lactide

AbstractThree new coordination polymers (CPs), {[Cu(NDC)(Fbtx)(H2O)] ⋅ 1.5H2O}n (1), {[Co(NDC)(Fbtx)(H2O)2] ⋅ 0.5Fbtx}n (2), and [Co2(NDC)2(Fbtx)]n (3), were synthesized by employing acid‐base mixed ligands of rigid 1,4‐naphthalenedicarboxylic acid (H2NDC) and flexible bis(1,2,4‐triazole‐1‐ylmethyl)‐2,3,5,6‐tetrafluorobenzene (Fbtx) under both hydrothermal and microwave‐assisted reaction conditions. Single‐crystal structure analysis establishted that both compounds 1 and 2 exhibit two‐dimensional (2D) layered structures, while compound 3 features a three‐dimensional (3D) complicated framework. The geometries of metal ions vary from square pyramidal (in 1 and 3) to distorted octahedral (in 2). Topological strudy showed that compounds 1 and 2 have exposed common 4‐connected 44‐sql net, while compound 3 has made a novel 4,5‐connected net with point symbol of (43 ⋅ 62 ⋅ 7)(43 ⋅ 64 ⋅ 72 ⋅ 8). The catalytic performance of the three complexes for the solvent‐free ring‐opening polymerization of L‐lactide has been investigated. The results indicated that compound 3 with coordinatively unsaturated cobalt(II) sites showed good activity and the molecular weight of the polymer obtained was high. Moreover, the complex 3 catalyst could be recycled up to five times with the retention of both catalytic activity and crystal structure.

Synthesis, crystal structures and luminescence properties of Zn(ii) and Cd(ii) coordination compounds assembled from flexible bis(quinolyl) ligands with symmetrical spacers: the influence of coordinated anions

Seven discrete compounds demonstrate that the diverse coordinating counterions and the different coordination modes of the iodide anion are advantageous in modulating the structures of the resulting coordination compounds.

Structural polymorphism and luminescence properties of zinc(ii) and cobalt(ii) MOFs with rigid and flexible ligands

Here, we present a series of Zn(ii) and Co(ii) coordination polymers containing two types of ligands: sterically rigid terephthalate derivatives (bdc-NO22− and bdc-Br2−) and flexible bis(2-methylimidazolyl)propane (bmip).

Series of Cadmium-Organic Frameworks Based on Mixed Flexible and Rigid Ligands: Single-Crystal-to-Single-Crystal Transformations, Sorption, and Luminescence Properties.

Here, we present a series of Cd(II) coordination polymers containing two types of ligands: sterically rigid terephthalate derivatives (bdc-NO22- and bdc-Br2-) and flexible bis(2-methylimidazolyl)propane (bmip). The combination of two types of ligands is used to obtain and characterize compounds by single crystal and powder X-ray diffraction, FT-IR, elemental analysis, and TGA. Guest exchange results in structural transformations. 2-fold interpenetrated 1·DMF and 2·DMF rapidly undergo to 4-fold interpenetrated 1·Et2O, 1·EtOH, and 1·H2O, or 2·Et2O, respectively. Also, changes in the coordinating numbers and length of the N,N'-donor bmip ligand were observed according to single crystal X-ray analysis. Activated guest-free compounds [Cd(bdc-NO2)(bmip)] (1) and [Cd(bdc-Br)(bmip)] (2) are shown to be porous with a BET surface area of 103 and 283 m2·g-1, respectively. Moreover, both compounds demonstrate gate-opening behavior of ethylene adsorption isotherms at low pressures (<1 bar) and highly selective adsorption of benzene over cyclohexane or lower alcohols. Also, both compounds demonstrate a strong dependence of the maximum of the photoluminescence emission on an excitation wavelength. As a result, the photoluminescence color changes from white to red and from blue to red through green and yellow for compounds 1 and 2, respectively, with excitation wavelength changing from 360 to 540 nm.

Syntheses, characterization of three new cobalt(II) complexes with 2-phenylsuccinic acid and flexible bis(imidazole) linkers

Bis(imidazole) derivatives (obix, mbix, pbix = 1,2-/1,3-/1,4-bis((imidazol-1-yl)methyl)benzene) with Co(II) and flexible 2-phenyl succinic acid (phsucH2) afforded three coordination polymers namely, [Co(µ-phsuc)(µ-obix)]n (1), {[Co(µ-phsuc)(µ-mbix)]⋅H2O}n (2), {[Co(µ4-phsuc)(µ-pbix)0.5]⋅H2O}n (3) and they were characterized by elemental analysis, magnetic susceptibility, solid-state UV–Vis. and IR spectroscopies and single crystal X-ray diffraction techniques. The phase purities of the complexes were confirmed by powder X-ray diffraction analysis. X-ray diffraction studies have shown that compounds 1 and 2 crystallize in the monoclinic system, in the P21/c space group, while compound 3 crystallizes in the P-1 space group in the triclinic system. In all compounds, bis(imidazole) ligands act as bis(monodentate), whereas 2-phenylsuccinate ligands act as both monodentate and bidentate bridges in 1, bis(monodentate) bridges in 2, tetrakis(monodentate) bridges in 3. The complexes displayed 2D layer structures and adjacent 2D layers are joined by C–H···π interactions in 1, weak C–H···O interactions in 2, π···π stacking and weak C–H···π interactions in 3 to form a 3D supramolecular network. The contribution of the binding positions of the imidazole groups to the phenyl ring in bis(imidazole) ligands to the structure and structural diversity are also discussed. In addition, the thermal properties of the compounds were investigated in the study.

Cage-like structures based on constrained cyclic arylopeptoids.

The access to cupola-like or tube-like structures from ortho- and meta-arylopeptoid macrocycles was explored through CuAAC reaction using a partially flexible bis(azide) and CuI-N-heterocyclic carbene as catalyst. NMR studies showed that a bis-triazolium bicylic compound in the ortho-series adopts well-defined structure in polar aprotic and protic solvents. Besides, preliminary study revealed its potential for oxoanion recognition.

Two 2D Polyoxometalate‐Based Metal‐Organic Complexes Constructed from a New Flexible N‐Donor Ligand with High Capacitance Performances and Low Detection Limits of Cr(VI)

AbstractBy designing and using a new flexible bis(pyrimidine)‐bis(amide) ligand H2L [H2L=N,N′‐bis(4‐pyrimidinecarboxamido)‐1,3‐propane], two new polyoxometalate (POM)‐based metal‐organic complexes (MOCs), H3[Cu2(L)2(PMo12O40)] (1) and [Cu2(H2L)2(β‐Mo8O26)] (2), were synthesized under solvothermal and hydrothermal conditions, respectively. In complexes 1 and 2, metal‐organic units and POM anions are linked together to form two distinct 2D structures. The [PMo12O40]3− (PMo12) anions were used as μ4‐bridging ligands in complex 1 and linked the 1D [Cu(L)]n metal‐organic chains to form a 2D layered structure. The [β‐Mo8O26]4− (Mo8) anions adopted two diverse coordination modes in complex 2 and connected the 1D [Cu(H2L)]n2n+ metal‐organic chains to generate a 2D grid structure. Complexes 1–2 can serve as electrode materials of supercapacitor and show large specific capacitances, up to 1065 and 956 F g−1 at current density of 2 A g−1, respectively, which surpass the parent POM and most of the previous reported POM‐based electrode materials, thus demonstrating the important role of introducing metal‐organic units in improving capacitive performances. Besides, the electrocatalytic redox activities of complexes 1–2 were also studied, both of them can be used as electrochemical sensors to detect Cr(VI) ions. They possess high sensitivity of 0.537 and 0.455 μA μM−1 and low detection limits of 0.16 and 0.33 μM, which are below the maximum content of Cr(VI) in groundwater required by the WHO.

An investigation of two heterobimetallic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes of a more flexible bis(salamo)‐type ligand

Two heterobimetallic [Cu(II)2Ln(III)] (Ln = La and Ce) complexes composed of flexible bis(salamo)‐type ligand H4L with Cu(II) and Ln(III) atoms, [Cu2La(L)(ƞ2-NO3)3]·EtOH (1) and [Cu2Ce(L)(ƞ2-NO3)3]·EtOH (2) have been successfully synthesized, and characterized by IR spectra, elemental analyses, UV–Vis spectroscopy, the crystal structures of the complexes 1 and 2 were determined by single-crystal X-ray diffraction analyses. Each Cu(II) atom of the complexes 1 and 2 is located in the N2O2-donor of the completely deprotonated (L)4− unit, so that the two Cu(II) atoms have tetra-coordinated slightly distorted square planar geometries, while the Ln(III) (La or Ce) atom is located in the O5 cavity of the ligand (L)4− unit. At the same time, there are six oxygen atoms from three bidentate nitrate groups coordinated with the Ln(III) (La or Ce) atom, resulting in the formation of an eleven-coordinated augmented sphenocorona J87. In addition, DFT calculations and Hirshfeld surfaces analyses are performed and fluorescence properties are evaluated.

Improved performance and stability of perovskite solar cells by iodine-immobilizing with small and flexible bis(amide) molecule

The iodine loss in the perovskite layer is currently-one of the major limit for further boosting power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). Iodine-poor interface dominates the generation of some deep level defects and the phase collapse in the perovskite layer. So how to adequately immobilize the iodine and passivate the existing undercoordinated lead cations is a critical challenge. Herein, the interaction between the bifunctional amide group and the perovskite layer was systematically investigated. The Malonamide (MAM) with bis(amide) group in structure can selectively hold iodine in place or interact with undercoordinated lead cations through adjusting the molecular conformation, resulting in more ideal I/Pb ratio, highly suppressed ion migration, harmonized surface potential and reduced defect density. Eventually, a significantly improved efficiency of 24.13% was demonstrated with the MAM-treating devices, and the device kept 96% of its initial efficiency after 900 h under continuous illumination.

Synthesis, crystal structure, fluorescence properties and theoretical calculations of heterobimetallic 3d–4f complex with a flexible bis(salamo)‐type ligand

A new heterobimetallic 3d-4f [Cu(II)2Pr(III)] complex [Cu2Pr(L)(ƞ2-NO3)3(EtOH)2]·2EtOH with a symmetric flexible bis(salamo)-type ligand, (1E,1′E)-2,3-dihydroxynaphthalene-1,4-dicarbaldehyde O,O-di(3-((((E)-3-ethoxy-2-hydroxybenzylidene)amino)oxy)propyl)dioxime (H4L), has been synthesized and characterized structurally. Single crystal X-ray diffraction analysis showed that the ligand was fasten by different metal ions to form a hetero-trinuclear complex with C-shaped structure, where two N2O2-donors of the completely deprotonated ligand (L)4− unit and two oxygen atoms from two ethanol molecules coordinate with Cu(II) atoms (Cu1, Cu2), respectively, to form two five-coordinated square pyramid geometries. Meanwhile, where the O6 cavity coordination sphere of the ligand (L)4− unit and six oxygen atoms from three nitrate groups coordinate with the Pr(III) atom together to form a twelve-coordinated icosahedron. Due to the Cu(II) atom in the O6 cavity was replaced by the Pr(III) atom, it shows that the hetero-trinuclear complex after self-assembly is more stable than the homo-trinuclear complex. At the same time, through UV–Vis titration spectrometric analysis, we can observed that the hetero-trinuclear [Cu(II)2Pr(III)] complex is obtained by 1 equiv. Pr(NO3)3·5H2O and 2 equiv. Cu(NO3)2·3H2O and 1 equiv. H4L. Significantly, fluorescence properties and Hirshfeld surfaces analyses of the [Cu(II)2Pr(III)] complex was also studied.

Synthesis, characterization, ion-exchange, and catalytic properties of three isostructural copper(II) coordination polymers with a flexible bis(triazole) ligand

Ion-exchange processes are shown to occur in several coordination polymers (CPs) and their unique subclass of metal-organic frameworks (MOFs). The development of fast and economical routes to stable ion-exchange CP materials is important to broaden the range of applications for these materials. Herein, we report a greatly improved synthesis and coordinated anion exchange of three new copper(II) coordination polymers [Cu(Fbtx)2(NO3)2]n (1), [Cu(Fbtx)2(BF4)2]n (2) and [Cu(Fbtx)2(SO4)]n (3) (Fbtx ​= ​1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene) under the microwave-assisted hydrothermal conditions. The three Cu-CPs are crystallographically isostructural, exhibiting two-dimensional layered structures with the 44-sql topology. Complexes 1–3 display good thermal stability and excellent chemical stability in organic solvents and aqueous solutions with wide pH range of 1–13. The anion-exchange functions of the series of sql-type coordination networks were monitored by using powder X-ray diffraction, infrared spectroscopy and ion chromatography. The results revealed that these complexes can undergo anion-exchange under microwave irradiation, and the reversible exchange process depends on the size of the anions. These materials were demonstrated to be efficient heterogeneous catalysts for the direct carboxylation of 1-ethynylbenzene with CO2 under mild conditions, and various propiolic acids were synthesized in moderate to good yields under optimized reaction conditions. Moreover, the catalyst could be recycled up to five times with the retention of both catalytic activity and crystal structure.

A series of coordination polymers constructed by 2-phenylsuccinic acid and flexible bis(imidazole) ligands: Syntheses, structures, and photoluminescent properties

Eight coordination polymers (CPs), namely, [Co(μ-phsuc)(μ-obix)]n(1), {[Co2(μ-phsuc)2(μ-pbix)1.5]⋅2H2O}n(2), [Zn(μ-phsuc)(μ-obix)]n(3), {[Zn(μ-phsuc)(μ-mbix)]⋅H2O}n(4), {[Zn(μ-phsuc)(μ-pbix)]⋅H2O}n(5), {[Zn(μ-phsuc)(μ-pbix)]⋅1.5H2O⋅CH3OH}n(6), [Cd(μ-phsuc)(μ-obix)]n(7) and [Cd(μ3-phsuc)(μ-pbix)0.5]n(8) (phsucH2 = 2-phenylsuccinic acid, obix = 1,2-bis((imidazol-1-yl)methyl)benzene, mbix = 1,3-bis((imidazol-1-yl)methyl)benzene, pbix = 1,4-bis((imidazol-1-yl)methyl)benzene), were solvothermally synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermal analyses. The structural analyses revealed that the compounds were 2D coordination polymers, in which metal ions were in tetrahedral coordination geometries in 1-6 and in octahedral coordination geometries in 2, 7 and 8. Compounds 1, 3, 4, 5, 7 and 8 displayed 4-connected 2D wave sheets with the point symbol of {44.62}. Compound 2 was rare example exhibiting a 2D polyrotaxane structure. Compound 6 showed a two-fold interpenetrated 2D structure with hcb topology (the point symbol of {63}). In the compounds, the neighboring 2D layers were further assembled by π⋅⋅⋅π stacking and weak C–H⋅⋅⋅π interactions into the 3D supramolecular framework. The effects of the bis(imidazole) linkers and metals ions on the framework assemblies have been discussed. In addition, thermal and photoluminescent and optical properties of the compounds were investigated.

Synthesis, Characterization, Ion-Exchange, and Catalytic Properties of Three Isostructural Copper(Ii) Coordination Polymers with a Flexible Bis(Triazole) Ligand

Synthesis, Characterization, Ion-Exchange, and Catalytic Properties of Three Isostructural Copper(Ii) Coordination Polymers with a Flexible Bis(Triazole) Ligand

A Series of Coordination Polymers Constructed by 2-Phenylsuccinic Acid and Flexible Bis(Imidazole) Ligands: Syntheses, Structures, and Photoluminescent Properties

A Series of Coordination Polymers Constructed by 2-Phenylsuccinic Acid and Flexible Bis(Imidazole) Ligands: Syntheses, Structures, and Photoluminescent Properties

Hydrogen bonds and dispersion forces serving as molecular locks for tailored Group 11 bis(amidine) complexes

A flexible polydentate bis(amidine) ligand operates as a molecular lock for CuCl, AgCl, AuCl, and AuMes fragments by forming flexible double macrocycles with N–H⋯R–M hydrogen bonds and additional distinct weak intramolecular forces.

Synthesis and structural characterization of two rotationally flexible bis(benzoxaphosphole)s

Two bis(benzoxaphosphole)s, 2,2′-diphenyl-7,7′-bibenzo[d][1,3]benzoxaphosphole (1) and 1,1′-bis(2-benzo[d][1,3]oxaphosphole)ferrocene (2) have been prepared and fully characterized, including structural characterization by single crystal X-ray diffraction methods. Compound 1 has flexibility about the connecting CC bond as evaluated by DFT calculations. The structure of 2 adopts a configuration in the solid state whereby the two BOP units are held in close proximity, presumably due to π-stacking interactions. Under UV irradiation compound 1 is blue fluorescent with a quantum yield of 18% in THF. Compound 2, however, displays no significant emission, which is attributed to ferrocene’s excited state quenching ability.

Two 2D metal–organic frameworks containing flexible bis(benzimidazole) derivatives for selective sensing of acetylacetone and Fe3+ ions

Two new metal–organic frameworks (MOFs), {[Co2(L)2(OBA)2]·3H2O}n (1) and {Zn(L)(OBA)]·H2O}n (2) were constructed via N-donor and dicarboxylic acids co-ligands (L = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)-2-propanol and H2OBA = 4,4′-oxybisbenzoic acid) under hydrothermal conditions and characterized by physico-chemical and spectroscopic methods. Two MOFs display 2D layers that are simplified as sql networks. 2 is further extended to 3D supramolecular framework via π–π stacking interactions. 1 and 2 feature high thermal and pH stability. Finally, both MOFs can serve as luminescence probes for sensing of acetylacetone and Fe3+ ions, the related sensing mechanisms are discussed in detail.

Crystal structure and physical properties of a new two-dimensional zinc coordination polymer based on 1,4-bis(4-(imidazole-1-yl)benzyl)piperazine and benzophenone-2,4′-dicarboxylate ligands

Abstract A new 2-dimensional (2D) zinc(II) coordination polymer based on a flexible bis(imidazole) ligand, namely, [Zn2(BIBP)(BPDC)2·DMF] n (1) BIBP is 1,4-bis(4-(imidazole-1-yl)benzyl)piperazine and H2BPDC is benzophenone-2,4′-dicarboxylic acid), has been synthesized and characterized through single-crystal X-ray diffraction, infrared (IR) spectroscopy, and elemental and thermal gravimetric analysis. Complex 1 exhibits a 2D framework oriented parallel to [0 2 1] based on [Zn(BPDC)] n chains. The fluorescence and catalytic properties of complex 1 for the photodegradation of methylene blue were investigated.

Two flexible bis(pyrazole)-bis(amide) ligand directed β-octamolybdate-based metal–organic complexes with different adsorption activities towards organic dyes and electrocatalytic properties

Two octamolybdate-based metal–organic complexes (MOCs) constructed from two flexible bis(pyrazole)-bis(amide) ligands, Ni(L1)(H2O)[β-Mo8O26]0.5 (1) and Ni(L2)(H2O)[β-Mo8O26]0.5 (2) (L1 = N, N-bis(3-pyrazolamide)-1,2-ethane, L2 = N, N-bis(3-pyrazolamide)-1,2-propane), have been prepared under hydrothermal conditions. Complexes 1 and 2 are isostructural and both of them present 1D chain structures, which are composed of [β-Mo8O26]4- anions and metal–organic loops [Ni2(L)2]4+ with different size. The complex 2 represents the first example of MOCs constructed from flexible bis(pyrazole)-bis(amide) L2 ligand. Complexes 1 and 2 show different adsorption behaviors towards methylene blue. Their electrocatalytic properties were investigated.