Metal Ion Ligand Research Articles

Resistive random access memory based on organic-metallic hybrid polymer

Abstract Resistive random access memories (ReRAMs) based on an organic-metallic hybrid polymer, Poly(Fe-btpyb) Purple, were fabricated. This material was synthesized by complexation of metal ion and organic ligand. When applying forward bias, an abrupt resistance change from a low resistance state (LRS) to a high resistance state (HRS), which is known as reset process, was observed. In contrast, a reverse bias switched the resistance from HRS to LRS (set process). The resistive switching phenomenon is probably caused by the electrochemical oxidation-reduction reaction of the metal ion (Fe(II)/Fe(III)). The nonvolatile memory characteristics were measured with data-retention tests, showing no significant degradation over 105 s. The endurance characteristics exhibited sufficient long-term durability, due to no conformational change of the organic ligand. It is proposed that the difference in charge-transfer efficiency between the reduced state (Fe(II)) and oxidized state (Fe(III)) might be the physical mechanism of the resistive switching.

Synchronized crystallization in tin-lead perovskite solar cells

Tin-lead halide perovskites with a bandgap near 1.2 electron-volt hold great promise for thin-film photovoltaics. However, the film quality of solution-processed Sn-Pb perovskites is compromised by the asynchronous crystallization behavior between Sn and Pb components, where the crystallization of Sn-based perovskites tends to occur faster than that of Pb. Here we show that the rapid crystallization of Sn is rooted in its stereochemically active lone pair, which impedes coordination between the metal ion and Lewis base ligands in the perovskite precursor. From this perspective, we introduce a noncovalent binding agent targeting the open metal site of coordinatively unsaturated Sn(II) solvates, thereby synchronizing crystallization kinetics and homogenizing Sn-Pb alloying. The resultant single-junction Sn-Pb perovskite solar cells achieve a certified power conversion efficiency of 24.13 per cent. The encapsulated device retains 90 per cent of the initial efficiency after 795 h of maximum power point operation under simulated one-sun illumination.

Design and Production of Functionalized Electrospun Fibers for Palladium Recovery.

Adsorption stands out as a leading wastewater treatment method for ion removal or recovery. Polymeric fibers, notably electrospun ones, are gaining prominence due to their high capacity and easy recovery. Electrospinning offers a cost-effective means to produce fibers with a large surface area and high adsorption capacity. These fibers can be further functionalized with chemical substances acting as specific ligands for metal ions, bolstering their adsorption capabilities. In this study, dithioester-functionalized electrospun fibers were synthesized as an alternative to conventional sorbents for palladium recovery from acidic chloride solutions, similar to those used in hydrometallurgical processes for platinum group metal recovery (Pd, Pt, Rh···) from spent catalysts. Fibers with identical chemical composition but varying morphology were examined to assess their impact on palladium adsorption efficiency (i.e., beads-free and beads-on-string morphologies). Experimental investigations involved model solutions with varying palladium concentration, temperature, acidity (adjusted with HCl content), and salinity (adjusted with NaCl), utilizing both pure and dithioester-functionalized fibers. Experimental results demonstrate enhanced adsorption efficiency at lower temperatures and in 0.1 M HCl, with a negligible influence from solution salinity. Moreover, both pure polymeric and dithioester-functionalized electrospun fibers exhibit highly efficient palladium recovery. Furthermore, under optimal conditions, starting from an 80 mg/L palladium solution, a 95% recovery of palladium can be achieved with a sorbent dosage below 4 g/L of functionalized electrospun fibers. The adsorption data are well described by the Langmuir isotherm model for the pure polymeric fibers. At the same time, the contribution of dithioesters has been separately accounted for to describe the behavior of functionalized electrospun fibers. Thermal recovery of palladium from the spent sorbents has also been investigated.

Integrating Prior Chemical Knowledge into the Graph Transformer Network to Predict the Stability Constants of Chelating Agents and Metal Ions.

The latest advancements in nuclear medicine indicate that radioactive isotopes and associated metal chelators play crucial roles in the diagnosis and treatment of diseases. The development of metal chelators mainly relies on traditional trial-and-error methods, lacking rational guidance and design. In this study, we propose the structure-aware transformer (SAT) combined with molecular fingerprint (SATCMF), a novel graph transformer network framework that incorporates prior chemical knowledge to construct coordination edges and learns the interactions between chelating agents and metal ions. SATCMF is trained on stability data collected from metal ion-ligand complexes, leveraging the SAT network to extract structural features relevant to the binding of ligands with metal ions. It further integrates molecular fingerprint features to refine the prediction of the stability constants of the chelating agents and metal ions. The experimental results on benchmark data set demonstrate that SATCMF achieves state-of-the-art performance based on four different graph neural network architectures. Additionally, visualizing the learned molecular attention distribution provides interpretable insights from the prediction results, offering valuable guidance for the development of novel metal chelators.

Electroless Copper Plating on a Cotton Surface: Effect of Metal Ion Ligand Stability Constant on Reduction Deposition.

Electroless plating facilitates the metallization of nonconductive substrate surfaces, and of note, the precise control of the bath stability constant influences the deposition process of metal particles. In this paper, trisodium citrate, potassium sodium tartrate, nitrogen triacetic acid, thiourea, and ethylenediamine tetraacetic acid disodium were selected as coordination agents, and the effect of the metal ion ligand stability constant on the reduction deposition was studied. Coordination bonds can be established between the Cu2+ and O/N/S particles in the ligand because paired electrons in O/N/S hybrid orbitals tend to occupy empty Cu2+ hybrid orbitals and establish coordination bonds. More importantly, the copper-potassium sodium tartrate ligand exhibits the lowest stability constant and lowest reduction barrier. As an exception, a consecutive Cu-plated coating with an excellent crystallinity property was deposited on the cotton surface when potassium sodium tartrate was used as the coordination agent in the plating solution. The deposition amounts are 55.2% and 74.1% after 1 and 4 h of electroless copper plating, respectively. The surface resistivity of Cu-plated cotton is 0.38 Ω/cm2, and additionally, the surface resistivity ratio before and after 1000 cycles fluctuated between 0.9 and 1.1, indicating that the Cu-plated cotton exhibits outstanding flexibility. In this paper, the deposition rate can be optimized by adjusting the copper particle ligand stability constant in the plating solution, aiming to achieve optimal results.

Rapidly prepared and screened supramolecular fluorescent sensors for the detection of metal ions

Fluorescent sensors capable of identification and quantitation of metal ions are of great importance for biological and environmental sciences. Supramolecular fluorescent sensors are designed and prepared based on the complexation of host-dye and ligand–metal ion. Two hosts, one commercially-available dye and eight ligands are used to form 16 potential three-component supramolecular sensors, which are screened to discover workable sensors. Among the workable sensors, one fluorescent sensor is capable of the identification of Cu2+ from nine other metal ions. Other suitable fluorescent sensors may be used for the quantitative analysis of metal ions in buffered solution, and metal sensing in live cells. This new analytical method provides an approach to rapidly generate sensors for different metal ions.

N-Alkylcorroles

A series of inner core [Formula: see text]-alkylcorroles were synthesized and characterized. The introduction of both linear and branched alkyl groups was achieved, demonstrating the quite large scope of the reaction. Polyalkylation results in the formation of the [Formula: see text]-21,[Formula: see text]-22 regioisomer, although the introduction of the second alkyl group is less facile than previously observed in the case of the methyl substituent. Complete functionalization of the inner core nitrogens has been investigated, but only the N,N′,N″-trimethyl derivatives were obtained. The characterization of these species demonstrated a different arrangement of the methyl groups to the macrocyclic plane, which is peculiar when compared with the conformation of the analogous porphyrin derivatives. These [Formula: see text]-alkylcorroles should prove to be of potential interest as ligands for various metal ions.

СИНТЕЗ НЕНАСЫЩЕННЫХ ХАЛЬКОГЕНОРГАНИЧЕСКИХ ЛИГАНДОВ НА ОСНОВЕ 1,2,3-ТРИХЛОРПРОПАНА

Unsaturated chalcogen-containing structures were obtained by condensation of 1,2,3-trichloropropane with organic dichalcogenides in the hydrazine hydrate–alkali system. Some of the synthesized com-pounds have proven themselves to be effective π,n-type ligands for heavy metal ions

Capturing cerium ions via hydrogel microspheres promotes vascularization for bone regeneration

The rational design of multifunctional biomaterials with hierarchical porous structure and on-demand biological activity is of great consequence for bone tissue engineering (BTE) in the contemporary world. The advanced combination of trace element cerium ions (Ce3+) with bone repair materials makes the composite material capable of promoting angiogenesis and enhancing osteoblast activity. Herein, a living and phosphorylated injectable porous hydrogel microsphere (P-GelMA-Ce@BMSCs) is constructed by microfluidic technology and coordination reaction with metal ion ligands while loaded with exogenous BMSCs. Exogenous stem cells can adhere to and proliferate on hydrogel microspheres, thus promoting cell-extracellular matrix (ECM) and cell-cell interactions. The active ingredient Ce3+ promotes the proliferation, osteogenic differentiation of rat BMSCs, and angiogenesis of endotheliocytes by promoting mineral deposition, osteogenic gene expression, and VEGF secretion. The enhancement of osteogenesis and improvement of angiogenesis of the P-GelMA-Ce scaffold is mainly associated with the activation of the Wnt/β-catenin pathway. This study could provide novel and meaningful insights for treating bone defects with biofunctional materials on the basis of metal ions.

DFT Exploration of Metal Ion-Ligand Binding: Toward Rational Design of Chelating Agent in Semiconductor Manufacturing.

Chelating agents are commonly employed in microelectronic processes to prevent metal ion contamination. The ligand fragments of a chelating agent largely determine its binding strength to metal ions. Identification of ligands with suitable characteristics will facilitate the design of chelating agents to enhance the capture and removal of metal ions from the substrate in microelectronic processes. This study employed quantum chemical calculations to simulate the binding process between eleven ligands and the hydrated forms of Ni2+, Cu2+, Al3+, and Fe3+ ions. The binding strength between the metal ions and ligands was quantified using binding energy and binding enthalpy. Additionally, we explored the binding interaction mechanisms and explained the differences in binding abilities of the eleven ligands using frontier molecular orbitals, nucleophilic indexes, electrostatic potentials, and energy decomposition calculations based on molecular force fields. Based on our computational results, promising chelating agent structures are proposed, aiming to guide the design of new chelating agents to address metal ion contamination issues in integrated circuit processes.

Unveiling the potential of redox electrolyte additives in enhancing interfacial stability for Zn-ion hybrid capacitors

Zinc-ion hybrid capacitors (ZICs) that combine the characteristics of metal-ion batteries and supercapacitors are emerging to fulfill high energy-power demands. The objective of this study is to address the challenges in the practical implementation of metallic zinc for ZICs. In this work, we explore redox molecules based on anthraquinone compounds as electrolyte additives for the interfacial engineering of Zn anodes. The results reveal that the additives enable favorable solvation of Zn2+ through metal ion-ligand coordination. The redox additives improve the lifespan of Zn//Zn cells from 50 to 1600 cycles at 2 mA cm−2 and 1 mAh cm−2 due to the suppression of parasitic reactions and the mitigation of by-product formations. The redox properties of additives strengthen the pseudocapacitive behavior of the ZICs, enabling efficient interfacial charge and mass transfer. The redox-enhanced device manifests an increased capacity of 195.0 mAh g − 1 with improved cycling stability, compared to that of 149.6 mAh g − 1 for the additive-free electrolyte. The universal strategy, based on the synergistic effects of redox additives, is demonstrated by a collection of molecules with similar structures. This work unveils a conceptually new approach that utilizes redox additives to formulate advanced electrolytes for aqueous energy storage.

Metal ion and organic ligand disubstituted bimetallic metal-organic framework nanosheets for high-performance alkaline zinc-based batteries.

Herein, a disubstitution strategy of metal ions and organic ligands is employed to synthesize metal-organic framework (MOF) nanosheets with a three-dimensional (3D) porous structure and a highly active metal-sulfur (M-S, M = Co and Ni) region. The obtained MOFs//Zn batteries exhibit excellent electrochemical properties and the electrochemical reaction mechanism was elucidated through a series of ex situ characterizations.

Quantitative measurement of cation-mediated adhesion of DNA to anionic surfaces.

Anionic polyelectrolytes, such as DNA, are attracted to anionic surfaces in the presence of multivalent cations. A major barrier toward molecular-level understanding of these attractive interactions is the paucity of measurements of the binding strength. Here, atomic force microscopy-based single molecule force spectroscopy was used to quantify the binding free energy of double-stranded DNA to an anionic surface, with complementary density functional theory calculations of the binding energies of metal ion-ligand complexes. The results support both electrostatic attraction and ion-specific binding. Our study suggests that the correlated interactions between counterions are responsible for attraction between DNA and an anionic surface, but the strength of this attraction is modulated by the identity of the metal ion. We propose a mechanism in which the strength of metal-ligand binding, as well as the preference for particular binding sites, influence both the concentration dependence and the strength of the DNA-surface interactions.

Synthesis of an alternating copolymer of the dense 1,2,3‐triazole backbone carrying t‐butyl ester and nitrile side chains

AbstractIn these decades, synthesis of polymers with controlled monomer sequences has been of increasing importance in polymer chemistry. When we tested synthesis of a heterodimer of 4‐azido‐5‐hexynoic acid derivatives carrying t‐butyl (tBu) ester and tBu amide side chains for preparation of an alternating copolymer, we unexpectedly obtained a heterodimer precursor carrying tBu ester and nitrile side chains, in a high yield. Since dense 1,2,3‐triazole polymers carrying nitrile side chains are expected as a new functional polymer, the heterodimer is polymerized by copper(I)‐catalyzed azide–alkyne cycloaddition polymerization to obtain an alternating copolymer carrying tBu ester and nitrile side chains in this study. Since 1,2,3‐triazole and nitrile moieties are known to be ligands for metal ions, the complex formation of the alternating copolymer with PdCl2 is also investigated by NMR. In the presence of PdCl2, 1H NMR spectra show broad and separated signals due to the free and complexed copolymers, indicative of slow exchange. Pulse‐field‐gradient spin‐echo NMR data indicated that the coordination of alternating copolymer to PdCl2 made the copolymer chains take a more compact conformation under dilute conditions. The density functional theory calculations indicated that the alternating copolymer coordinated to PdCl2 preferentially through the 1,2,3‐triazole nitrogen and nitrile nitrogen atoms.

MOFGalaxyNet: a social network analysis for predicting guest accessibility in metal–organic frameworks utilizing graph convolutional networks

Metal–organic frameworks (MOFs), are porous crystalline structures comprising of metal ions or clusters intricately linked with organic entities, displaying topological diversity and effortless chemical flexibility. These characteristics render them apt for multifarious applications such as adsorption, separation, sensing, and catalysis. Predominantly, the distinctive properties and prospective utility of MOFs are discerned post-manufacture or extrapolation from theoretically conceived models. For empirical researchers unfamiliar with hypothetical structure development, the meticulous crystal engineering of a high-performance MOF for a targeted application via a bottom-up approach resembles a gamble. For example, the precise pore limiting diameter (PLD), which determines the guest accessibility of any MOF cannot be easily inferred with mere knowledge of the metal ion and organic ligand. This limitation in bottom-up conceptual understanding of specific properties of the resultant MOF may contribute to the cautious industrial-scale adoption of MOFs.Consequently, in this study, we take a step towards circumventing this limitation by designing a new tool that predicts the guest accessibility—a MOF key performance indicator—of any given MOF from information on only the organic linkers and the metal ions. This new tool relies on clustering different MOFs in a galaxy-like social network, MOFGalaxyNet, combined with a Graphical Convolutional Network (GCN) to predict the guest accessibility of any new entry in the social network. The proposed network and GCN results provide a robust approach for screening MOFs for various host–guest interaction studies.

Metal-Promoted Higher-Order Assembly of Disulfide-Stapled Helical Barrels.

Peptide-based helical barrels are a noteworthy building block for hierarchical assembly, with a hydrophobic cavity that can serve as a host for cargo. In this study, disulfide-stapled helical barrels were synthesized containing ligands for metal ions on the hydrophilic face of each amphiphilic peptide helix. The major product of the disulfide-stapling reaction was found to be composed of five amphiphilic peptides, thereby going from a 16-amino-acid peptide to a stapled 80-residue protein in one step. The structure of this pentamer, 5HB1, was optimized in silico, indicating a significant hydrophobic cavity of ~6 Å within a helical barrel. Metal-ion-promoted assembly of the helical barrel building blocks generated higher order assemblies with a three-dimensional (3D) matrix morphology. The matrix was decorated with hydrophobic dyes and His-tagged proteins both before and after assembly, taking advantage of the hydrophobic pocket within the helical barrels and coordination sites within the metal ion-peptide framework. As such, this peptide-based biomaterial has potential for a number of biotechnology applications, including supplying small molecule and protein growth factors during cell and tissue growth within the matrix.

Recent Progress and Future Prospects of Laccase Immobilization on MOF Supports for Industrial Applications.

Laccase is a multicopper oxidoreductase enzyme that can oxidize organics such as phenolic compounds. Laccases appear to be unstable at room temperature, and their conformation often changes in a strongly acidic or alkaline environment, making them less effective. Therefore, rationally linking enzymes with supports can effectively improve the stability and reusability of native enzymes and add important industrial value. However, in the process of immobilization, many factors may lead to a decrease in enzymatic activity. Therefore, the selection of a suitable support can ensure the activity and economic utilization of immobilized catalysts. Metal-organic frameworks (MOFs) are porous and simple hybrid support materials. Moreover, the characteristics of the metal ion ligand of MOFs can enable a potential synergistic effect with the metal ions of the active center of metalloenzymes, enhancing the catalytic activity of such enzymes. Therefore, in addition to summarizing the biological characteristics and enzymatic properties of laccase, this article reviews laccase immobilization using MOF supports, as well as the application prospects of immobilized laccase in many fields.

Biosensors Based on the Binding Events of Nitrilotriacetic Acid-Metal Complexes.

Molecular immobilization and recognition are two key events for the development of biosensors. The general ways for the immobilization and recognition of biomolecules include covalent coupling reactions and non-covalent interactions of antigen-antibody, aptamer-target, glycan-lectin, avidin-biotin and boronic acid-diol. Tetradentate nitrilotriacetic acid (NTA) is one of the most common commercial ligands for chelating metal ions. The NTA-metal complexes show high and specific affinity toward hexahistidine tags. Such metal complexes have been widely utilized in protein separation and immobilization for diagnostic applications since most of commercialized proteins have been integrated with hexahistidine tags by synthetic or recombinant techniques. This review focused on the development of biosensors with NTA-metal complexes as the binding units, mainly including surface plasmon resonance, electrochemistry, fluorescence, colorimetry, surface-enhanced Raman scattering spectroscopy, chemiluminescence and so on.

Unusual Effect of Minor Change in Ligand Substitution in Modulation of NIR Emission: A Case Study with [L-ZnII-LnIII] Complexes.

There have been numerous instances of lanthanide NIR emitting material where one or more types of ligands or metal ion-ligand complexes operate as antennas. The antenna's role in NIR emission has also been thoroughly investigated and validated. The emission properties of the different antennae are predicted to differ. Here we describe the structural and photophysical properties of two series of [ZnII-LnIII] complexes, where a minor difference between the two series (ethoxy vs methoxy substitution) affected the photophysical properties, particularly the f-f transition, in an unprecedented manner. Both steady-state and time-resolved luminescence spectra were affected by this change. Detailed single-crystal X-ray diffraction (SCXRD) and X-ray photoelectron spectroscopy (XPS) studies of both complexes revealed the crucial structural differences in crystal packing, which astonishingly remains unaffected in solution.

Development of novel aspartic acid-based calcium bio-MOF designed for the management of severe bleeding

The synthesis of amino acid-based MOF using calcium as metal ion and l-aspartic acid biocompatible ligand for management of severe bleeding.