Metal Cluster Ions Research Articles

Delivery of cations (Mg2+, Al3+, Ga3+, Sn2+, Cr3+, Fe3+) into the cells by anthocyanins through Physico-chemical assessment: A molecular simulation study

Anthocyanins (ACNs) are secondary metabolites responsible for most of the red to purple pigmentation found in flowers, fruits, and leaves. Clusters of metal ions of Mg2+, Al3+, Ga3+, Sn2+, Cr3+, Fe3+ joined to ACNs in water media were studied for unraveling the color shifting of different complexes of these structures in the low ranges of pH. In this verdict, it has been studied the metallic cations diffusing of deprotonating for the anthocyanin (ACN) (B)-ring of Malvidin (Mal), Peonidin (Peo), Delphinidin (Del), Pet, and Cyanidin (Cya) in water. The difference of heat of formation (∆Hf) among clusters of metallic cations jointed to ACNs has been illustrated toward the double bonds and carbonyl groups by the chelation of (B)-ring for cyanidin, delphinidin and petunidin ACNs in two media of gas and water that explains the stability and color of [ACN-metallic cations] cluster chelation. The complexes of Ga3+ → Pet, Cr3+ → Pet, Mg2+ → Pet and Al3+ → Cya, Ga3+ → Cya, Mg2+ → Cya have indicated the maximum absorbance in the low concentration. The mechanism of cation-induced ACNs mainly depends on the location of active zones of functionalized O-atoms in ACN and divalent or trivalent cations characteristics. Regarding the obtained results, regular consumption of some vegetables and fruits, which are rich in ACN molecules, should be helpful to stop viral infectious by decreasing pathogenicity and propagation of viral diseases.

Metal organic framework (MOF): Synthesis and fabrication for the application of electrochemical sensing

Metal-organic frameworks (MOF) are a class of porous hybrid materials of metal ions linked by organic bridging ligands. These materials consist of different families of crystalline frameworks with metal ions and metal-ion clusters linked by the coordination bonds with suitable organic ligands. These porous materials possess high surface area, variable pore sizes, various functions, and excellent thermal stability. As a result, these unique and tailored MOF materials found varied applications in electrochemical sensor development. The review critically examines the approach to synthesizing a wide range of MOF compounds. The utilization of MOF in fabricating a small-scale sensor device demonstrates the ability to detect various water contaminants in aquatic environments. Moreover, it showcased an in-depth advancement in sensor and device development utilizing MOFs materials. The efficient use of electrochemical sensors is discussed critically and presents these studies’ challenges and future perspectives.

Entropy measures of the metal–organic network via topological descriptors

Abstract A family of chemical compounds known as metal–organic networks (MONs) is composed mainly of clusters of metal ions with organic ligands. It can increase volatility or make substances soluble in organic solvents. By using these salient features, organic compounds generate applications in material sciences for sol–gel processing. A graph’s entropy is utilized as a complexity indicator and is interpreted as the structural information content of the graph. Investigating the entropies of relationship systems is a common occurrence in discrete mathematics, computer science, information theory, statistics, chemistry, and biology. In this article, we investigated the degree-based entropies: geometric arithmetic entropy, atom bond connectivity entropy, general Randic′ entropy, and general sum connectivity entropy for MONs. Furthermore, we created tables for all expressions by using 1–10 values for the s s parameter of these entropies.

Construction of 2D layered metal‐organic frameworks based on the norbornene‐derived ligand with fascinating magnetic and luminescent properties

AbstractThree new two‐dimensional metal‐organic frameworks (MOFs), namely [Cu3(NDIC)3 ⋅ C2H5OH ⋅ 2H2O]n (1), [Co2(NDIC)2 ⋅ 2 C3H7NO ⋅ H2O]n ⋅ nC2H5OH (2) and [(Zn3O)2(Zn(H2O)4)(NDIC)6 ⋅ C3H7NO ⋅ C2H5OH ⋅ C2H5O ⋅ 7H2O]n (3) based on the ligand 5‐norbonene‐2,3‐dicarboximide isophthalic acid (H2NDIC) have been synthesized under solvothermal condition, which have been further characterized by single crystal X‐ray diffraction analysis, powder X‐ray diffraction ( PXRD) elemental analysis, ICP, TG and FT‐IR spectroscopy. The ligand displayed distinctive coordination modes to connect mononuclear metal ion, binuclear and trinuclear metal clusters to generate different 2D layered structures in compound 1–3. Compound 1 shows KGM type network based on paddle‐wheel Cu2(COO)4 as secondary building units (SBUs). Compounds 2 and 3 have the undulating 2D (4, 4) SQL topology with the point symbol (44 ⋅ 62) based on Co2(COO)4 and Zn3(μ3‐O)(COO)4 as SBUs, respectively. The magnetic properties of compound 1–2 and the luminescent property of compound 3 and its fluorescent detection for Fe3+ has been investigated and discussed.

Concomitant role of metal clusters and ligands in the synthesis and control of porosity in Metal-Organic Frameworks: A literature review

A clossal increase in the number of research articles on metal–organic frameworks (MOFs) have recently been anticipated as next-generation functional materials. The characteristic coordination behavior between metal ion and organic linker in MOFs provide them hydrid functional features of both the moieties. For the substantial improved performance of MOFs and to achieve widespread applications of MOFs in diverse fields, it is essential to develop effective synthetic strategies and understand the role of metal ion cluster or coordination sphere or secondary building units (SBU’s) and organic linker in detail. The augmentation in porosity and large surface area with multitude in diverse topologies provide a boost for the application of these materials in diverse allied fields. This review article provides a detailed introduction of the porous MOF materials; encompassing the role of secondary building units or metal cluster and organic linkers in defining the porosity of MOF materials. Detailed investigations about the role of metal ion clusters and expanded organic linkers that lead to MOFs with ultrahigh porosity have been done and portrayed carefully. The structural aspects of zirconium, zinc and copper cluster based porous MOFs and organic linkers (porphyrin and pyrene based) have been thoroughly portrayed owing to their various application in various fields. This review article will provide better understanding about the various factors involved in synthesis and controll of the porosity toward desired applications.

Ionization of aluminum clusters

Near-threshold photoionization cross sections for several aluminum clusters have been estimated from the ionization efficiency curves. Their magnitude raises the possibility that the edge of a collective electron resonance (surface plasmon) may contribute to the photoemission channel. On the other hand, electron impact ionization efficiently produces multiply charged metal cluster ions and is unaccompanied by noticeable fragmentation. Consequently it does not appear to involve collective excitations.

Recent Progress in the Application of Metal Organic Frameworks in Surface-Enhanced Raman Scattering Detection

Metal–organic framework (MOF) compounds are centered on metal ions or metal ion clusters, forming lattices with a highly ordered periodic porous network structure by connecting organic ligands. As MOFs have the advantages of high porosity, large specific surface area, controllable pore size, etc., they are widely used in gas storage, catalysis, adsorption, separation and other fields. SERS substrate based on MOFs can not only improve the sensitivity of SERS analysis but also solve the problem of easy aggregation of substrate nanoparticles. By combining MOFs with SERS, SERS performance is further improved, and tremendous research progress has been made in recent years. In this review, three methods of preparing MOF-based SERS substrates are introduced, and the latest applications of MOF-based SERS substrates in biosensors, the environment, gases and medical treatments are discussed. Finally, the current status and prospects of MOF-based SERS analysis are summarized.

Analytical performance of single particle aerosol mass spectrometer for accurate sizing and isotopic analysis of individual particles

The commercial Hexin Single particle aerosol mass spectrometer (SPAMS) has been widely used for environmental aerosol monitoring and source apportionment. However, particle size measurement is easily affected by environment pressure fluctuation and sampling orifice clogging. The capability for quantitative analysis is poor, and few isotope measurement has been reported. This paper aims to evaluate the analytical performance of SPAMS and extend its application. First, the flight time of standard particles having different densities and sizes was measured under various conditions (aerodynamic lens upstream pressure and carrier gas). We proposed a universal method for particle size calibration, measurement and correction, taking into account the effects of lens geometry (acceleration nozzle diameter), particle parameters (density, diameter, and shape factor), and operating conditions (lens upstream pressure and carrier gas). Then, isotope measurement was performed when introducing a solution droplet containing a single element. Metal oxide and metal cluster ions were observed in the mass spectrum, indicating incomplete ionization of the sample droplet. The mass discrimination effect was carefully evaluated to correct the measured isotope ratio. Results show that the achievable accuracy of the corrected isotope ratio for elements investigated was 5%. The instrumental performance was relatively poor for elements having great ionization potential or bond energy. Finally, Ag/Eu2O3 suspension and yellow cake/ethanol suspension were analyzed for size, elemental and isotopic analysis. We confirmed that the mass discrimination effect during suspension introduction could be corrected using the mass discrimination correction factor obtained during solution introduction. The Ag, Eu and U in these suspension particles were all found to be at natural abundance. The uranium in the yellow cake was identified as sodium duranyate (Na2U2O7) with volumetric equivalent diameter of approximately 65 nm. The work presented here is beneficial for instrument improvement and wide application.

In silico simulations for prediction and modeling of protein engineering within catalytic subunit of direct electron transfer type FAD glucose dehydrogenase for increases in substrate specificity and structural stability.

The bacterial flavin adenine dinucleotide (FAD) glucose dehydrogenase (FADGDH) is composed of three subunits; 1) a catalytic subunit which belongs to the glucose-methanol-choline (GMC) oxidoreductase family contains an FAD cofactor and 3Fe-4S cluster in its redox center, 2) a hitchhiker protein subunit functioning in the bacterial TAT secretion system, and 3) a membrane-bound subunit with three heme c moieties, responsible for the transfer of electrons between the active-site cofactor and external electron acceptors. The presence of the electron transfer subunit makes this enzyme able to transfer electron directly to the electrode, thereby designates this enzyme as a direct electron transfer (DET) type GDH. The recent X-ray crystal structure elucidation of its catalytic subunit complexed with small subunit, revealed the unique substrate binding cavity of this enzyme. This enzyme was then mutated within its substrate pocket to increase substrate specificity towards glucose as a validation for later energy minimization and molecular dynamics simulations using AMBER MD. Modeling both the FAD and 3Fe-4S cluster elucidated a new methodology for modeling proteins involving covalent bonding of cofactors and namely metal ion cluster harboring proteins. From this modeling, the electron transfer pathway involving both cofactors and metal ion clusters can be further investigated in DET type enzymes. With these new modeling techniques, we can take a new approach in designing future mutational candidates by first evaluating them in silico then applying those results to our wet lab testing for higher throughput and a more targeted approach in designing and creating mutations.

Metal-organic coordination polymers for delivery of immunomodulatory agents, and infectious disease and cancer vaccines.

Metal-organic coordination polymers (CPs) are a broad class of materials that include metal-organic frameworks (MOFs). CPs are highly ordered crystalline materials that are composed of metal ions (or metal ion clusters) and multidentate organic ligands that serve as linkers. One-, two-, and three-dimensional CPs can be formed, with 2D and 3D structures referred to as MOFs. CPs have gained a lot of attention due to attractive structural features like structure versatility and tunability, and well-defined pores that enable the encapsulation of cargo. Further, CPs show a lot of promise for drug delivery applications, but only a very limited number of CPs are currently being evaluated in clinical trials. In this review, we outlined features that are desired for CP-based drug delivery platform, and briefly described most relevant characterization techniques. We highlighted some of the recent efforts directed toward developing CP-based drug delivery platforms with the emphasis on vaccines against cancer, infectious diseases, and viruses. We hope this review will be a helpful guide for those interested in the design and evaluation of CP-based immunological drug delivery platforms. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A novel peptide hydrogel of metal ion clusters for accelerating bone defect regeneration.

In the absence of adequate treatment, effective bone regeneration remains a great challenge. Exploring hydrogels with properties of excellent bioactivity, stability, non-immunogenicity, and commercialization is an important step to develop hydrogel-based bone regeneration materials. In this study, we engineered a self-assembled chelating peptide hydrogel loaded with an osteogenic metal ion cluster extracted from the processed pyritum decoction, including Fe2+, Cu2+, Zn2+, Mn2+, Mg2+, and Ca2+ ions, named processed pyritum hydrogel (PPH). We demonstrated that as a reservoir of beneficial metal ion clusters in bone regeneration, PPH has been shown to regulate a variety of genes in the process of bone regeneration. These genes are mainly involved in extracellular matrix synthesis, cell adhesion and migration, cytokine expression, antimicrobial and inflammation. Therefore, PPH accelerated the progress of various bone healing stages, and shortened the bone healing cycle by 4weeks. Our investigation outcomes showed that the engineered metal ion cluster hydrogel is a novel, simple, and commercializable bone-regenerating hydrogel with potential clinical use.

Capturing the Trajectory of Metal-Ion-Cluster Formation: Stepwise Accumulation of Zn(II) Ions in a Robust Coordination Space Formed by a Rigid Tridentate Carboxylate Ligand.

Organic ligand-directed synthesis of metal-ion clusters with a well-defined number and arrangement of metal ions is an important subject toward the development of functional inorganic-organic nanohybrids. Here we report the synthesis of multinuclear Zn-oxo clusters using a triptycene-based rigid ligand (H3L) featuring three metal-coordination sites arranged in a triangular shape. Upon complexation of H3L with zinc acetate dihydrate, a decanuclear Zn-oxo cluster and multinuclear Zn-oxo clusters with a smaller number of Zn(II) ions were formed as the final product and its intermediates, respectively. A comparison of the X-ray structure of the final product with those of the intermediates revealed the cluster-formation process, where four triptycene ligands preorganize to form a robust coordination space to which Zn(II) ions accumulate in a stepwise manner. This stepwise metal-ion accumulation, along with the formation of a large tetrahedral decanuclear Zn-oxo cluster, highlights the potential of ligand design using 1,8,13-substituted triptycenes for the development of various metal-ion clusters.

An uncommon [K+(Mg2+)2] metal ion triad imparts stability and selectivity to the Guanidine-I riboswitch.

The widespread ykkC-I riboswitch class exemplifies divergent riboswitch evolution. To analyze how natural selection has diversified its versatile RNA fold, we determined the X-ray crystal structure of the Burkholderia sp. TJI49 ykkC-I subtype-1 (Guanidine-I) riboswitch aptamer domain. Differing from the previously reported structures of orthologs from Dickeya dadantii and Sulfobacillus acidophilus, our Burkholderia structure reveals a chelated K+ ion adjacent to two Mg2+ ions in the guanidine-binding pocket. Thermal melting analysis shows that K+ chelation, which induces localized conformational changes in the binding pocket, improves guanidinium-RNA interactions. Analysis of ribosome structures suggests that the [K+(Mg2+)2] ion triad is uncommon. It is, however, reminiscent of metal ion clusters found in the active sites of ribozymes and DNA polymerases. Previous structural characterization of ykkC-I subtype-2 RNAs, which bind the effector ligands ppGpp and PRPP, indicate that in those paralogs, an adenine responsible for K+ chelation in the Burkholderia Guanidine-I riboswitch is replaced by a pyrimidine. This mutation results in a water molecule and Mg2+ ion binding in place of the K+ ion. Thus, our structural analysis demonstrates how ion and solvent chelation tune divergent ligand specificity and affinity among ykkC-I riboswitches.

The Modulating Effect of Ethanol on the Morphology of a Zr-Based Metal–Organic Framework at Room Temperature in a Cosolvent System

We report that ethanol, used together with water, plays a crucial role in tuning the structures of a zirconium-based metal–organic framework and the 12-connected MOF-801, as well as the possible mechanisms of this modulating effect. By employing a cosolvent system of ethanol and water at just under room temperature without the presence of a monotopic carboxylic acid as the modulator, MOF-801 in various morphologies of different sizes could be synthesized. A linear correlation between the ethanol/water ratio and the crystal sizes is also demonstrated. The growth mechanism is mainly explained by ethanol’s bonding with the metal ion clusters and the Marangoni flow effect. Ethanol competes with the linker molecules in coordinating with the Zr metal clusters, a role similar to that of the modulators. The Marangoni flow effect, which dominates at a certain solvent ratio, further promotes the 1D alignment of the MOF-801 crystals.

Pristine, metal ion and metal cluster modified conjugated triazine frameworks as electrocatalysts for hydrogen evolution reaction

Two covalent triazine frameworks with homoporous and heteroporous structures were modified with metal ions and metal clusters. Their electrocatalytic hydrogen evolution reaction exhibits good performance with low overpotential and small Tafel slope.

Various Effects of Alkali Metal Ions on H2O2 Reduction Reactions at Pt Electrodes

The hydrogen peroxide reduction reaction (HPRR) has attracted much attention because it is involved in the oxygen reduction reaction which is an important cathode reaction in several fuel cell systems. Pt has an excellent electrocatalytic activity toward the HPRR. Thus, the HPRR at Pt electrodes has been widely studied including effects of electrolyte components and additives on it.Katsounaros and Mayrhofer have reported that alkali metal cations such as Li+, Na+, and K+ inhibit the HPRR in basic media [1]. The hydrated alkali metal cations and chemisorbed OH species on Pt, denoted as M+(H2O) x and OHads respectively, non-covalently stabilize each other, leading to the formation of quasi-specifically adsorbed hydrated metal ion clusters that blocks electrochemical reactions. The inhibition becomes stronger as the strength of the non-covalent interaction increases (K+ < Na+ < Li+), and consequently the rest potential decreases in this order, as reproduced in Figure 1a.We have recently found that the HPRR in strongly acidic media is also affected by the alkali metal ions. As shown in Figure 1b, the HPRR is inhibited at U < 0.7 V in the presence of the ions. This indicates that the alkali metal ions inhibit the transport of electroactive species, namely, H+ and H2O2, toward the electrode surface. The HPRR current becomes smaller (in absolute value) in the following order: Li+ < Na+ < K+, that is, the inhibition becomes stronger in the reverse order of the strength of the non-covalent interaction. In this work, to explain this inhibition, we study the HPRR by electrochemical impedance method.Interestingly, the metal ions induce a significance increase in the local pH at the electrode surface (pHs) during the HPRR when the concentration of H2O2 is relatively high, that is, when the HPRR consumes a large amount of H+ [2]. For instance, the pHs becomes strongly basic when 0.01 M H2SO4 + 0.05 M H2O2 + 0.05 M M2SO4 (where M stands for Li, Na, and K) is used as the electrolyte solution. We thus think that the non-covalent interaction can be induced during the HPRR even in the acidic media. Note that the pHs remains acidic in the case of Figure 1b because of the lower concentration of H2O2. In this work, we summarize the above-mentioned effects of the alkali metal ions on the HPRR. REFERENCES [1] I. Katsounaros and K. J. J. Mayrhofer, Chem. Commun., 48, 6660-6662 (2012).[2] Y. Mukouyama, H. Kawasaki, D. Hara, Y. Yamada, S. Nakanishi, J. Electrochem. Soc., 164 (2017) H675. FIGURE CAPTION Figure 1. The current (I) – potential (E) curves for a Pt-plate electrode in basic and acidic solutions measured under potential controlled conditions at a scan rate of 0.01 Vs-1. The basic solutions are 0.05 M alkali hydroxide (denoted as MOH) + 0.01 M H2O2, and the acidic ones are 0.05 M H2SO4 + 0.01 M H2O2 with or without 0.05 M alkali sulfate (denoted as M2SO4). Figure 1

Activation of dinitrogen by gas-phase species

Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes. Activation of the very inert N≡N triple bond of dinitrogen molecule by isolated gas-phase species has attracted considerable interest in the past few decades. Apart from molecular adsorption and dissociative adsorption, interesting processes such as C-N coupling and degenerate ligand exchange were discovered. The present review focuses on the recent progress on adsorption, activation, and functionalization of N2 by gas-phase species (particularly metal cluster ions) using mass spectrometry, infrared photo-dissociation spectroscopy, anion photoelectron spectroscopy, and quantum chemical calculations including density functional theory and high-level ab initio calculations. Recent advances including characterization of adsorption products, dependence of clusters’ reactivity on their sizes and structures, and mechanisms of N≡N weakening and splitting have been emphasized and prospects have been discussed.

Polyoxometalates in Biomedicine: Update and Overview.

Polyoxometalates (POMs) are negatively charged metal-oxo clusters of early transition metal ions in high oxidation states (e.g., WVI, MoVI, VV). POMs are of interest in the fields of catalysis, electronics, magnetic materials and nanotechnology. Moreover, POMs were shown to exhibit biological activities in vitro and in vivo, such as antitumor, antimicrobial, and antidiabetic. The literature search for this peer-reviewed article was performed using PubMed and Scopus databases with the help of appropriate keywords. This review gives a comprehensive overview of recent studies regarding biological activities of polyoxometalates, and their biomedical applications as promising anti-viral, anti-bacterial, anti-tumor, and anti-diabetic agents. Additionally, their putative mechanisms of action and molecular targets are particularly considered. Although a wide range of biological activities of Polyoxometalates (POMs) has been reported, they are to the best of our knowledge not close to a clinical trial or a final application in the treatment of diabetes or infectious and malignant diseases. Accordingly, further studies should be directed towards determining the mechanism of POM biological actions, which would enable fine-tuning at the molecular level, and consequently efficient action towards biological targets and as low toxicity as possible. Furthermore, biomedical studies should be performed on solutionstable POMs employing physiological conditions and concentrations.

Structure, optical and magnetic properties of a novel homometallic coordination polymers: Experimental and Computational studies

Single crystal of 1D homometallic coordination polymer involving cobalt metal ion and P2Mo5 Strandberg type polyoxometallate cluster (C6H10N2)2[Co(H2O)4P2Mo5O23].6H2O, is prepared in aqueous solution and characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance, fluorescence and magnetism. Single crystal X-ray diffraction analysis reveals that this compound crystallizes in the triclinic system with space group P ,bar{1}. The 3-(ammoniomethyl)pyridine C6H8N2 organic fragment is used merely as stabilizer for the promotion of topological structure. DRS data indicate that the synthesized material can be identified as a ferromagnetic semiconductor with optical bands gaps energy of 1.81 and 2.74 eV, respectively. The large value of refractive index observed in the visible region make the simple a promising candidate for visible optical communication devices and fluorescent emisson result provides that the complex belongs to a blue luminescent compounds. Moreover, magnetic measurements and electronic structure calculations show that P2Mo5 Strandberg polyoxoanion can be reported as a new class of ligand that is candidate to construct metal-inorganic framworks with long distance ferromagnetic superechange between Co(II) centers. The evidence from this study suggests that the syntesized polymer can become a great multifunctional material openning the door for the developpement of new coordination polymers based on Strandberg type polyxoxmetalate with potential applications.

Mg2+ vs Ca2+ bound active site of group II intron– A MD study

Group II introns are enzymes which undergo self-splicing and remove itself from pre-messenger RNA. X-ray structures of group II intron of Oceanobacillus iheyensis at various stages of the self-splicing pathway (pre-hydrolytic, post-hydrolytic, and ligand-free state) revealed intricate atomic interaction network in the active site of the intron. It has been confirmed that a heteronuclear metal ion cluster consisting of four metal ions (K1, K2 sites with K+ and M1, M2 sites with Mg2+) are crucial for function. Substitution of Mg2+ by Ca2+ results in loss of enzymatic activity. The X-ray structures not only opens up the possibility of modelling Mg2+ and Ca2+ bound active site of group II intron and quantitatively estimate the energetics of Mg2+ vs Ca2+ preference but also explore the relative structural and dynamical differences in response to divalent metal ion substitution. Thus, using X-ray structures as a template we performed molecular dynamics simulations to compare structural and dynamical differences between Mg2+ and Ca2+ bound active site of group II intron at various stages of the splicing pathway (i.e., pre-hydrolytic, post-hydrolytic, and ligand-free state). Quantitative estimation of Mg2+ vs Ca2+ selectivity at the M1, M2 sites confirmed Mg2+ preference at intron active sites relative to Ca2+. Ca2+ is relatively more hydrated in the intron active site relative to Mg2+. The local environment (bound nucleophilic water, interaction with scissile phosphate) around M2 is strikingly different between Mg2+ and Ca2+ bound pre-hydrolytic state. In the post-hydrolytic state, the exon part of the hydrolysis product is involved in direct interaction with the M1, whereas the intron part is highly flexible in our MD trajectories. Solvent exposure of M1, M2 sites are least in the pre-hydrolytic state, highest in the ligand-free state, and intermediate in the post-hydrolytic state.