Search Results (127)

The reaction of copper nitrate, phthalic acid (1,2-H₂BDC), and bipyridine in ammonia/ethanol media affords two multi-copper (II) cluster-based coordination polymers, namely {[Cu₄(bpy)₄(OH)₂(BDC)₂]·2OH·13H₂O}_n (USC-CP-6) and {[Cu₂(BDC)₂(bpy)₂(H₂O)]·3H₂O}_n (USC-CP-7), under ambient conditions, with CP-6 forming at the bottom and CP-7 at the upper edge of the same beaker. The single-crystal structures reveal that it is a rare case of gradient-induced formation of different multi-copper(II) cluster-based CPs within a single-solution chemical reaction. CP-6 crystallizes in the monoclinic system, sp. gr. P2₁/c, and is composed of chair-like tetranuclear [Cu₄(μ₃-OH)₂(bpy)₄(BDC)₂]²⁺ clusters as secondary building units, bridged by BDC²⁻ ligands to form a two-dimensional layer framework, while CP-7 crystallizes in the monoclinic system, sp. gr. P2₁/n, with binuclear [Cu₂(1,2-BDC)₂(bpy)₂(H₂O)] clusters linked by bridging BDC²⁻ ligands to form a one-dimensional looped double chain. Through intermolecular π–π stacking and hydrogen bonds between the coordination water, lattice water, and free oxygen atoms from carboxylate, both compounds yield a 3D supramolecular structure. Full article

Five new coordination compounds that included three coordination polymers and two supramolecular complexes were obtained by reactions of different cadmium salts (tetrafluoroborate, nitrate, and perchlorate) with dianiline chromophores, 4,4′-diaminodiphenylmethane (ddpm), and 4,4′-diaminodiphenylethane (ddpe). The crystal structures were studied by single-crystal X-ray analysis. The coordination arrays with the ddpm chromophore included {[Cd(OH)(H₂O)(ddpm)₂](BF₄)}_n (1) as a one-dimensional (1D) coordination garland chain, {[Cd(NO₃)(ddpm)₂](H₂O)(NO₃)}_n (2) as a two-dimensional (2D) coordination layer, and [Cd(bpy)₂(ddpm)₂](ddpm)(NO₃)₂ (3) as a supramolecular complex. The products with the ddpe chromophore were identified as {[Cd(phen)₂(ddpe)](ClO₄)₂}_n (4) in the form of a linear coordination chain and [Cd(phen)₃](ClO₄)₂(ddpe)_0.5(CH₃CN)_0.5 (5) as a supramolecular complex. The extension of coordination arrays in 1, 2, and 4 was achieved via dianiline ligands as bidentate linkers and additionally via bridging of nitrate anions in 2. The diversification of products became possible due to usage of 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) as co-ligands forming the terminal corner fragments [Cd(bpy)₂]²⁺, [Cd(phen)₂]²⁺, and [Cd(phen)₃]²⁺ in 3–5, respectively. The assembling of coordination entities occurred via the interplay of hydrogen bonds with the participation of amino groups, water molecules, and inorganic anions. Two dianilines were powerful luminophores in the crystalline phase, while the photoluminescence in 1–5 was considerably weaker than in the pure ddpm and ddpe luminophores and redistributed along the spectrum. Full article

The electrocatalyst layers (ECLs) in polymer electrolyte membrane (PEM) electrolyzers are fundamentally comprised of IrOx catalysts, support material, and an ionomer. Their stability is critically dependent on structure and composition, necessitating a thorough understanding of ionization potential and work function. We employ Density Functional Theory (DFT) to determine the ionization states of ECLs and to optimize their electronic properties. Furthermore, advanced deep learning simulations (DLSs) significantly enhance the kinetic and transport behaviors of these layers. This work integrates DFT and DLS to elucidate the characteristics of ECLs within PEM electrolyzer cells. We strategically utilize DFT to refine catalyst molecules and assess their electronic properties, while DLS is employed to predict the potential energy of support molecules in the catalyst layers. We establish a clear relationship between the energy and geometry of IrOx molecules. The DFT-DLS framework robustly calculates potential energy and reaction coordinates, effectively bridging theoretical computations with the dynamic behavior of molecules in catalyst layers. We validate our model by comparing it with the experimental polarization curve of the IrOx-based anode catalyst layer in a functioning electrolyzer. The observed Tafel slope and exchange current density unequivocally confirm that the oxygen evolution reaction (OER) occurs through a well-defined electrochemical pathway, with oxygen generation proceeding according to the charge transfer mechanism predicted by the DFT-DLS framework. Full article

Chiral layered coordination polymers have attracted considerable attention not only because of their intriguing physicochemical properties but also because of their ability to exfoliate into chiral nanosheets. Chiral metal phosphonates with layered structures are of particular interest due to their relatively high thermal and water stabilities, but their corresponding nanosheets are rarely reported on. Herein, we report on a pair of enantiopure zinc phosphonates with the formula S- and R-Zn₈(cyampH)₈Cl₈ (S-Zn, R-Zn), where S- and R-cyampH₂ represent S- and R-(1-cyclohexylamino)methylphosphonic acids. They have layered structures in which the {ZnO₃Cl} tetrahedra are connected by {PO₃C} tetrahedra via corner-sharing. By doping analogous chromophore ligands S- and R-(1-naphthalenethylamino)methylphosphonic acid (S-, R-nempH₂), we obtained compounds S- and R-Zn₈(cyampH)_8-n(nempH)_nCl₈ (S-, R-Zn-x%, x = 2, 4, 6), which exhibited obvious circular dichroism (CD) and circularly polarized luminescence (CPL) properties. The bulk samples of S-Zn and S-Zn-4% were further subjected to exfoliation in acetone, resulting in chiral nanosheets of one–three-layer thicknesses. Full article

We report the synthesis and characterization of new, user-friendly gold(I) [Au₄(μ-(NH)₂CC₂F₅)₄]_n coordination polymer and [Au₂Cl₂(NH₂(NH=)CC₂F₅)₂]_n complex. These compounds were investigated for potential application as precursors in chemical vapor deposition (CVD) and focused electron/ion beam-induced deposition (FEBID/FIBID), which are additive methods to produce nanomaterials. Single-crystal X-ray diffraction, elemental analysis, and infrared spectroscopy were used to determine the complexes’ composition and structure. We studied their thermal stability and volatility using thermal analysis and variable-temperature infrared spectroscopy (VT IR) and by conducting sublimation experiments. The gold(I) amidinate [Au₂(μ-(NH)₂CC₂F₅)₂]_n sublimates at 413 K under 10⁻² mbar pressure. The electron-induced decomposition of the complexes’ molecules in the gas phase and of their thin layers on silicon substrates was analyzed using electron impact mass spectrometry (EI MS) and microscopy studies (SEM/EDX), respectively, to provide insights for FEBID and FIBID precursor design. The [Au₂Cl₂(NH₂(NH=)CC₂F₅)₂]_n hydrogen chloride molecules evolved during heating, with the formation of gold(I) amidinate. The obtained results revealed that the new gold(I) amidinate may be a promising source of metal for nanomaterial fabrication by gas-assisted methods. Full article

Herein, we present the synthesis and structural characterisation of two layered MOFs with the asymmetric ligand 3-chloro,6-cyano-2,5-dihydroxy-1,4-benzoquinone dianion (C₆O₄(CN)Cl²⁻ = chlorocyananilato). These compounds, formulated as (H₃O)[Eu(C₆O₄(CN)Cl)₂(H₂O)]·34H₂O (1) and (H₃O)[Dy(C₆O₄(CN)Cl)₂(H₂O)]·44H₂O (2), are isostructural and show a (4,4)-layered square structure with the crystallisation water molecules located between the layers. The lanthanoid ions are surrounded by four bis-bidentate chlorocyananilato ligands that connect each Ln^III centre with other four, giving rise to square cavities formed by Ln^III centres in the vertices and chlorocyananilato ligands as the sides. There is an additional coordinated water molecule that occupies the caped position of the capped square antiprismatic coordination geometry around the Ln^III centres. The magnetic properties show the presence of a field-induced slow relaxation of the magnetisation in the Dy^III derivative at low temperatures that follows Direct and Orbach relaxation mechanisms with an energy barrier of 36(3) K. Full article

The ethanol–water layered syntheses and crystal structures of the coordination polymers [Cd(C₁₇H₂₂N₂)₂(H₂O)₂]·2(ClO₄)·C₁₇H₂₂N₂·C₂H₅OH 2 and [Cd(C₁₇H₂₂N₂)₂(NO₃)₂] 3 are reported, where C₁₇H₂₂N₂ is a flexible spacer, 1,7-bis(4-pyridyl)heptane. In compound 2, trans-CdO₂N₄ octahedral nodes are linked by pairs of bridging ligands to result in [001] looped polymeric chains. The chains stack in the [100] direction to form (010) pseudo layers. Sandwiched between them are secondary sheets of free ligands, perchlorate ions and ethanol solvent molecules. Hydrogen bonds between these species help to consolidate the structure. Compound 3 contains trans-CdO₂N₄ octahedral nodes as parts of regular 4⁴ nets, which propagate in the (103) plane. Three independent nets are interpenetrated. Full article

A systematic investigation of optical, electrochemical, photophysical, and electrooptical properties of printable green color-emitting polymer (poly(9,9-dioctylfluorene-alt-bithiophene)) (F8T2) and spiro-copolymer (SPG-01T) was conducted to explore their potentiality as an emissive layer for wearable polymer light-emitting diode (PLED) applications. We compared the two photoactive polymers in terms of their spectral characteristics and color purity, as these are the most critical factors for wearable lighting sources and optical sensors. Low-cost, solution-based methods and facile architecture were applied to produce rigid and flexible light-emitting devices with high luminance efficiencies. Emission bandwidths, color coordinates, operational characteristics, and luminance were also derived to evaluate the device’s stability. The tuning of emission’s spectral features by layer thickness variation was realized and was correlated with the interplay between H-aggregates and J-aggregates formations for both conjugated polymers. Finally, we applied the functional green light-emitting PLED devices based on the two studied materials for the detection of Rhodamine 6G. It was determined that the optical detection of the R6G photoluminescence is heavily influenced by the emission spectrum characteristics of the PLED and changes in the thickness of the active layer. Full article

A Dy(III) coordination polymer (CP), [Dy(spasds)(H₂O)₂]_n (1) (Na₂Hspasds = 5-(4-sulfophenylazo)salicylic disodium salt), has been synthesized using a hydrothermal method and characterized. 1 features a 2D layered structure, where the spasda³⁻ anions act as pentadentate ligands, adopting carboxylate, sulfonate and phenolate groups to bridge with four Dy centers in η₃-μ¹: μ², η₂-μ¹: μ¹, and monodentate coordination modes, respectively. It possesses a unique (4,4)-connected net with a Schläfli symbol of {4⁴·6²}{4}₂. The luminescence study revealed that 1 exhibited a broad fluorescent emission band at 392 nm. Moreover, the visual blue color has been confirmed by the CIE plot. 1 can serve as a dual-functional luminescent sensor toward Fe³⁺ and MnO₄⁻ through the luminescence quenching effect, with limits of detection (LODs) of 9.30 × 10⁻⁷ and 1.19 × 10⁻⁶ M, respectively. The LODs are relatively low in comparison with those of the reported CP-based sensors for Fe³⁺ and MnO₄⁻. In addition, 1 also has high selectivity and remarkable anti-interference ability, as well as good recyclability for at least five cycles. Furthermore, the potential application of the sensor for the detection of Fe³⁺ and MnO₄⁻ was studied through simulated wastewater samples with different concentrations. The possible sensing mechanisms were investigated using Ultraviolet-Visible (UV-Vis) absorption spectroscopy and density functional theory (DFT) calculations. The results revealed that the luminescence turn-off effects toward Fe³⁺ and MnO₄⁻ were caused by competitive absorption and photoinduced electron transfer (PET), and competitive absorption and inner filter effect (IFE), respectively. Full article

The reactions of the angular ligand 4,4′-oxybis(N-(pyridin-3-yl)benzamide) (L¹) and 1,4-naphthalenedicarboxylic acid (1,4-H₂NDC) with divalent metal salts yielded three distinct coordination polymers (CPs): {[Zn₂(L¹)(1,4-NDC)₂]·MeOH}_n, 1, {[Cu(L¹)(1,4-NDC)(H₂O)]·3H₂O}_n, 2, and {[Cd(L¹)(1,4-NDC)]·2H₂O}_n, 3. Complex 1 features a 2-fold interpenetrated 3D framework with the (4¹²·6³)-pcu topology, while complex 2 reveals a 1D triple-strained helical chain and complex 3 displays a 3-fold interpenetrated 3D framework with (6⁶)-dia topology. Additionally, the reactions of the flexible ligand N,N′-bis(3-methylpyridyl) adipoamide (L²) afforded {[Co₄(L²)_0.5(1,4-NDC)₃(H₂O)₃(µ₃-OH)₂]·EtOH·2H₂O}_n, 4, {[Zn₂(L²)(1,4-NDC)₂]·2CH₃OH}_n, 5, and [Cd(L²)(adipic)(H₂O)]_n (H₂adipic = adipic acid), 6, exhibiting a self-catenated 3D framework with the (4²⁰·6⁸)-8T32 topology, a 2D layer with the (4¹³·6²) − (4,4)IIb topology, and a 2D layer with the (4⁴·6²)-sql topology, respectively. The structural diversity observed in complexes 1–6 highlights the pivotal influence of the metal center on the degree of entanglement in CPs within mixed-ligand systems. The thermal stability and luminescent properties of complexes 1–3, 4, and 6 are also discussed. Full article

The industrial adoption of material extrusion of polymers (MEX/P) is hindered by the geometric quality of manufactured parts. Contact image sensors (CISs), commonly used in flatbed scanners, have been proposed as a suitable technology for layer-wise characterization of contour deviations, paving the way for the application of corrective measures. Nevertheless, despite the high resolution of CIS digital images, the accurate characterization of layer contours in MEX/P is affected by contrast patterns between the layer and the background. Conventional edge-recognition algorithms struggle to comprehensively characterize layer contours, thereby diminishing the reliability of deviation measurements. In this work, we introduce a novel approach to precisely locate contour points in the context of MEX/P based on evaluating the similarity between the grayscale pattern near a particular tentative contour point and a previously defined gradient reference pattern. Initially, contrast patterns corresponding to various contour orientations and layer-to-background distances are captured. Subsequently, contour points are identified and located in the images, with coordinate measuring machine (CMM) verification serving as a ground truth. This information is then utilized by an adaptive edge-detection algorithm (AEDA) designed to identify boundaries in manufactured layers. The proposed method has been evaluated on test targets produced through MEX/P. The results indicate that the average deviation of point position compared to that achievable with a CMM in a metrology laboratory ranges from 8.02 µm to 13.11 µm within the experimental limits. This is a substantial improvement in the reliability of contour reconstruction when compared to previous research, and it could be crucial for implementing routines for the automated detection and correction of geometric deviations in AM parts. Full article

The study presented herein concerns the mechanical properties of two common polymers for potential biomedical applications, PLA and PETG, processed through fused filament fabrication (FFF)—Material Extrusion (ME). For the uniaxial tension tests carried out, two printing orientations—XY (Horizontal, H) and YZ (Vertical, V)—were considered according to the general principles for part positioning, coordinates, and orientation typically used in additive manufacturing (AM). In addition, six specimens were tested for each printing orientation and material, providing insights into mechanical properties such as Tensile Strength, Young’s Modulus, and Ultimate Strain, suggesting the materials’ potential for biomedical applications. The experimental results were then compared with correspondent mechanical properties obtained from the literature for other polymers like ASA, PC, PP, ULTEM 9085, Copolyester, and Nylon. Thereafter, fatigue resistance curves (S-N curves) for PLA and PETG, printed along 45°, were determined at room temperature for a load ratio, R, of 0.2. Scanning electron microscope observations revealed fibre arrangements, compression/adhesion between layers, and fracture zones, shedding light on the failure mechanisms involved in the fatigue crack propagation of such materials and giving design reference values for future applications. In addition, fractographic analyses of the fatigue fracture surfaces were carried out, as well as X-ray Computed Tomography (XCT) and Thermogravimetric (TGA)/Differential Scanning Calorimetric (DSC) tests. Full article

A reaction between copper(II) nitrate and trans-1,4-cyclohexanedicarboxylic acid (H₂chdc) carried out under hydrothermal conditions led to a new metal-organic coordination polymer [Cu₂(Hchdc)₂(chdc)]_n. According to single-crystal XRD data, the compound is based on bi-nuclear paddlewheel-type carboxylate blocks that are joined with polymeric chains due to the (μ₃-κ¹:κ²) coordination of carboxylate groups. The chains are interconnected by chdc²⁻ bridging ligands into layers containing free COOH groups of terminal Hchdc⁻. The neighboring layers adopt a RCOOH···OOCR hydrogen bond-assisted arrangement into a dense-packed structure. Magnetization measurements showed the presence of a strong antiferromagnetic exchange interaction (J/k_B = −495 K) inside the bi-nuclear blocks. At the same time, no significant interaction was found between the {-Cu₂(OOCR)₄-} units in spite of their polymeric in-chain packing. Patterns of magnetic behavior of [Cu₂(Hchdc)₂(chdc)]_n were thoroughly analyzed and explained from a structural point of view. Full article

As one of the most important sources for green hydrogen, anion exchange membrane water electrolyzers (AEMWEs) have been developing rapidly in recent decades. Among these components, anion exchange membranes (AEMs) with high ionic conductivity and good stability play an important role in the performance of AEMWEs. In this study, we have developed a simple blending method to fabricate the blended membrane ImPSF-PEGx via the introduction of a hydrophilic PEG into the PSF-based ionic polymer. Given their hydrophilicity and coordination properties, the introduced PEGs are beneficial in assembling the ionic groups to form the ion-conducting channels. Moreover, an asymmetric structure is observed in ImPSF-PEGx membranes with a layer of finger-like cracks at the upper surface because PEGs can act as pore-forming agents. During the study, the ImPSF-PEGx membranes exhibited higher water uptake and ionic conductivity with lower swelling ratios and much better mechanical properties in comparison to the pristine ImPSF membrane. The ImPSF-PEG1000 membrane showed the best overall performance among the membranes with higher ionic conductivity (82.6 mS cm⁻¹ at 80 °C), which was approximately two times higher than the conductivity of ImPSF, and demonstrated better mechanical and alkaline stability. The alkaline water electrolyzer assembled by ImPSF-PEG1000 achieved a current density of 606 mA cm⁻² at 80 °C under conditions of 1 M KOH and 2.06 V, and maintained an essentially unchanged performance after 48 h running. Full article

Metal-coordinated hydrogels are becoming increasingly popular in the biomedical field due to their unique properties. However, the mechanism behind gel forming involving metal ions is not yet fully understood. In this work, terahertz spectroscopy was used to investigate the role of interfacial water in the gelation process of copper ion-coordinated poly(vinyl alcohol) hydrogels. The results showed that the binding of copper ions could alter the interfacial hydration dynamics of the poly(vinyl alcohol) polymers. Combined with the results of differential scanning calorimetry (DSC), we propose a possible hydration layer-mediated mechanism for the formation of cooper ion-coordinated hydrogel during the freeze–thaw cycle. These results highlight the value of terahertz spectroscopy as a sensor for studying the hydration process in hydrogels and provide an important clue for understanding the mechanism of hydrogelation in ion-coordinated hydrogels. Full article