Formation Of Coordination Bonds Research Articles

(5-Fluoro-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-1-ido-κN 1)(1,4,8,11-tetraazacyclotetradecane-κ4 N)zinc(II) perchlorate

In the structure of the title complex, [Zn(C4H2FN2O2)(C10H24N4)]ClO4, the zinc(II) ion forms coordination bonds with the four nitrogen atoms of cyclam (1,4,8,11-tetraazacyclotetradecane or [14]aneN4) as well as with the nitrogen atom of a deprotonated 5-fluorouracil ion (FU−). Cyclam adopts a trans-I type conformation within this structure. The coordination structure of the zinc(II) ion is a square pyramid with a distorted base plane formed by the four nitrogen atoms of the cyclam. FU− engages in intermolecular hydrogen bonding with neighboring FU− molecules and with the cyclam molecule.

Solvation structure design for stabilizing MXene in transition metal ion solutions

AbstractAlthough MXene has attracted great interest in diverse fields, it is susceptible to oxidation in water (H2O) with transition metal ions such as Co2+, Fe2+, and Cu2+, which is pronounced at high temperatures. This impedes the preparation of MXene‐based composites and their functional applications. Here, this study revealed that Co2+ increases the maximum and average atomic charge of H in H2O to improve the reactivity of H2O, which leads to the fact that Co2+ catalyzes the oxidation of Ti3C2Tx MXene. Furthermore, the addition of N,N‐dimethyl formamide (DMF) reduces the H2O activity and improves the oxidation stability of Ti3C2Tx in the presence of Co2+ via preferentially forming coordination bonds with Co2+. This strategy is also effective in enhancing the oxidation tolerance of Ti3C2Tx to Fe2+ in H2O. Moreover, it is feasible to enhance the oxidation stability of Ti2CTx MXene in H2O with the existence of Co2+. By virtue of these, the CoO/Ti3C2Tx composite was successfully prepared without obvious Ti3C2Tx oxidation, which is desirable to harness the advantages of Ti3C2Tx as the complementary component for lithium‐ion batteries. This work provides a straightforward paradigm to enhance the oxidation resistance of MXene in H2O in the presence of transition metal ions and at high temperatures, which opens a new vista to use MXene for target applications.

A turn-off fluorescent sensor based on Schiff base incorporating diformyl phenol moiety for the detection of Cu2+ in aqueous solution at nanomolar level and its application in living cells

Given the critical role of trace copper ion in human health, its sensitive detection in environmental and biological samples is crucial. We, herein, designed and synthesized a diformyl phenol-based turn-off fluorescent sensor ((5-(tert-butyl)-2-hydroxy-1,3-phenylene)bis (methanylylidene)) bis (azanylylidene)) bis(4-hydroxy-2H-chromen-2-one) (MH-4)) for the spectrofluorometric detection of Cu2+ ion, which has sensitive and selective fluorescence quenching over other competitive metal ions. The efficiency and fast response of the sensor were confirmed by UV–Visible, fluorescence spectral changes, which may be due to the formation of coordination bond between MH-4 and Cu2+ ions. The binding stoichiometry of MH-4 with Cu2+ was examined with the help of UV–Vis and fluorescence titrations, and Job’s plot, which gives a 1:1 coordination stoichiometry; this is further confirmed through MS studies. The binding constant of the complex was found to be 9.4 x 107 M−1. Then, the absorbance and fluorescence-based detection limits were calculated to define the sensitivity range of the proposed sensor and were found to be 69.30 nM and 37.40 nM, respectively. Finally, a live cell image study of MH-4 in L929 (murine aneuploid fibrosarcoma) cells was also performed to test the cell permeability of MH-4 and its effectiveness for selective detection of Cu2+ in living cells.

Wood dimensional stability enhancement by multivalent metal-cation-induced lignocellulosic microfibrils crosslinking

Wood is a hygroscopic material that responds to the moisture changes of the surrounding environment through swelling and shrinkage, making it dimensionally unstable. Here, we introduce a facile metal-ion-modification (MIM) approach to enhance the dimensional stability of wood. The MIM process involved swelling the wood samples with aqueous metal ion solutions and drying. The high valent metal cations, such as Fe3+, Al3+, and Zr4+, interacted with the hydrophilic groups (e.g., OH, COOH) present in the wood fibers, limiting their access to water and moisture, thereby enhancing the wood's hydrophobicity and dimensional stability. Evaluation of three wood species, southern yellow pine, poplar, and red oak, revealed water contact angles of 120–130° after MIM, indicative of enhanced surface hydrophobicity. Fe3+ treatment decreased southern yellow pine's swelling ratio from 6 % to 4 %. Fe3+-treated wood exhibited tangential anti-swelling efficiencies ranging from 39.83 % to 57.14 % and radial anti-swelling efficiencies from 34.74 % to 48.33 %, varying across wood species. The enhancement of wood dimensional stability can be attributed to the formation of irreversible coordination bonds between metal cations and lignocellulosic microfibrils in the wood cell wall. These bonds prevent the microfibrils from slipping in response to moisture absorption and desorption.

The influence of cyclodextrin on hydrophobicity of pipeline and asphalt distribution: A green and efficient corrosion inhibitor

Corrosion inhibitors face significant limitations due to their non-degradability and poor applicability to asphalt systems. The molecular simulation studies show that cyclodextrin (CD) and asphalt can form supramolecular corrosion inhibitors with pipeline hydrophobic modification and corrosion inhibition effects. In particular, the rich hydroxyl structure of CD enables it to stably bind to the pipeline by forming coordination bonds and feedback bonds. When 2 CD molecules are added, the initial wetting time of the emulsion is delayed by 257.81 % compared to Span 80 with the same mass fraction. When 4 CD molecules are added, the emulsion cannot wet the iron surface within the simulation time. Furthermore, the combination of CD and asphalt allows more than 90 % of the asphalt to emulsify and prevent the emulsion from spreading on the pipeline. This results in a synergistic corrosion inhibition effect. These findings suggest that CD-based supramolecular corrosion inhibitors have the potential to be effective and environmentally friendly alternatives to traditional inhibitors in asphalt systems.

Z-Type Ligand Enables Efficient and Stable Deep-Blue Perovskite Light-Emitting Diodes.

During the synthesis of deep-blue perovskite quantum dots (PQDs), they generally emerge as a two-dimensional byproduct with poor yield and low photoluminescence quantum yield (PLQY) due to amine ligand enrichment-induced abundant surface defects. Herein, we provide a colloidal synthesis method to prepare deep-blue CsPbBr3 PQDs in a green nontoxic solvent via strategic Z-type ligand engineering. Z-type ligands of zinc octanoate enable the formation of robust coordination bonds with surface bromide ions of PQDs, maintaining acid-base equilibrium and reducing excess amine enrichment on the PQDs surface. Consequently, homogeneous and monodispersed PQDs with improved PLQY of 73% are successfully synthesized, achieving efficient deep-blue LEDs with a peak EQE of 5.46%, a maximum luminance of 847.6 cd/m2, and an operational half-lifetime of 14 min. The devices exhibit color coordinates of (0.137, 0.049), closely approximating the Rec. 2020 blue standard. Our work offers a potentially eco-friendly and viable route for realizing high-performance LEDs in the deep-blue region.

Amphiphilic Post‐Modification of Red Algae‐Derived Carrageenan Coatings for Balanced Marine Antifouling Applications

AbstractPolysaccharide coatings are of interest for marine antifouling applications because of their good marine antifouling properties and environmentally benign characteristics. However, the hydrophilic nature of polysaccharide coatings can lead to the adsorption of marine sediment, which can negatively impact their antifouling properties. Amphiphilic modification of polysaccharide coatings has been demonstrated to address these issues. In this study, we report a simple method for post‐modification of a sulfated polysaccharide carrageenan (CAR) coating to make it amphiphilic. A hydrophilic CAR coating is first formed on solid substrates, followed by grafting hydrophobic molecules onto the CAR‐coated surfaces through metal‐ion‐mediated coordinate bond formation. The resulting amphiphilic CAR coating effectively reduces both marine sediment (silt) adsorption and marine diatom adhesion, achieving a balanced marine antifouling performance.

Camellia meal-based adhesive with synergistic crosslinking of physical and chemical interaction for preparing aldehyde-free, anti-mildew, water-resistant wood-based composites

Wood adhesives containing toxic aldehyde-based adhesives play a vital role in the performance of wood-based panels, while the mechanical properties and water and mildew resistance of aldehyde-free adhesives are lacking. In this study, a high-strength aldehyde-free adhesive was constructed via a combination of physical and chemical crosslinks. Inexpensive alum was used to ensure a high degree of crosslinking and to increase the crystallinity. Metal ions in alum opened the protein helix, exposed the active groups, increased the number of hydrogen bonds, and ultimately improved the internal physical crosslinking ability of the adhesive. The compound formed by the Schiff base reaction formed coordination bonds with metal ions, thus forming a covalently-crosslinked network. The high-strength polymer produced in this study contained multiple physical and covalent crosslinks, resulting in significantly improved mechanical properties of the adhesive. Its water-resistant adhesive strength reached 1.96 MPa, which was 180.2% higher than that of ordinary phytogenic protein adhesive (0.69 MPa), and it can still reach 1.28 MPa after hot water circulation soaking experiment. The adhesive also possessed antifungal properties and flame-retardant capabilities, achieving a V-1 rating in the UL-94 test. This strategy expanded the application of phytogenic protein adhesives in environmentally friendly wood composite materials by replacing synthetic resins that released formaldehyde and provided an economical and feasible industrial scale production method for the preparation of high strength, water, and mildew resistant, flame retardant indoor and outdoor wood-based panels.

Metal-Assisted Carbohydrate Assembly.

The sequence-controlled assembly of nucleic acids and amino acids into well-defined superstructures constitutes one of the most revolutionary technologies in modern science. The elaboration of such superstructures from carbohydrates, however, remains elusive and largely unexplored on account of their intrinsic constitutional and configurational complexity, not to mention their inherent conformational flexibility. Here, we report the bottom-up assembly of two classes of hierarchical superstructures that are formed from a highly flexible cyclo-oligosaccharide─namely, cyclofructan-6 (CF-6). The formation of coordinative bonds between the oxygen atoms of CF-6 and alkali metal cations (i) locks a myriad of flexible conformations of CF-6 into a few rigid conformations, (ii) bridges adjacent CF-6 ligands, and (iii) gives rise to the multiple-level assembly of three extended frameworks. The hierarchical superstructures present in these frameworks have been shown to modulate their nanomechanical properties. This research highlights the unique opportunities of constructing convoluted superstructures from carbohydrates and should encourage future endeavors in this underinvestigated field of science.

Metal Complexes of Adenine Azo Ligand: Synthesis, Identification and Study some of their Applications

This scientific paper presents two novel lanthanide metal complexes [Sm (III) and Ce (IV)] synthesized through a series of reactions involving organic ligand 8-[3-(pyrazoyl)azo]adenine (PAA). Ligand (PAA) and their complexes were characterized using various analytical techniques, including C.H.N.S elemental analysis, magnetic measurement, X-ray diffraction, thermal analysis, SEM, (TGA) UV-Vis spectroscopy, FT-IR spectroscopy, and HNMR analysis. These techniques were employed to support the mode of binding and geometrical structure for ligand (PAA) and its Lanthanide (Ln) complexes. The FTIR and HNMR spectral results showed that (PAA) acts as neutral N,N-bidentate with [Sm (III) and Ce (IV)]. The geometric shape of the synthesized Ln-complexes is octahedral. Also, TGA was used to investigate the thermal behavior of ligand and its complex. The results showed that the ligand dissociated in three steps, while the complex dissociated in five steps. This indicates that the complex is more thermally stable than the ligand, likely due to the formation of strong coordination bonds between the ligand and the metal ions. These findings can contribute to the understanding of the thermal stability of metal complexes and inform the design of new metal-based materials with desirable properties. Finally, this paper examined the antibacterial, antifungal and anticancer activities of PAA and its complexes. The results indicated that all of these compounds exhibited significant activity against bacterial and fungal pathogens, as well as cancer cells.

Improved photothermal properties of a functionalized polydopamine mediated by chelating iron ions

Because of its good photothermal conversion performance, biocompatibility and adhesion of polydopamine nanoparticles (PDA NPs), PDA has been widely used in the biomedical field. However, its hydrophilicity and stability are not good, and the photothermal properties and absorbance of PDA need to be improved. Functionalized polydopamine nanoparticles (NPDA NPs) were prepared by chelating iron ions to solve this problem. The photothermal conversion capacity and light absorption capacity of NPDA were significantly improved. This was attributed to the catalytic effect of iron ions, which can promote the oxidation reaction of PDA and increase the number of oxygen-containing functional groups. The stability of NPDA was significantly enhanced, which was attributed to the fact that iron ions can form coordination bonds with some phenolic hydroxyl groups in PDA. Additionally, there was no significant difference between the photothermal properties of NPDA and drug-loaded NPDA. Two kinds of drug-loaded NPDA NPs, celecoxib loaded NPDA (NPDA@Cel) and desferrioxamine mesylate loaded NPDA (NPDA@DFO), exhibited drug release properties in slightly acidic environment. Near infrared light promoted drug release of NPDA@Cel. This paper provides new ideas for the biomedical applications of PDA nanomaterials.

Recently Reported Biological Activities and Action Targets of Pt(II)- and Cu(II)-Based Complexes.

Most diseases that affect human beings across the world are now treated with drugs of organic origin. However, some of these are associated with side effects, toxicity, and resistance phenomena. For the treatment of many illnesses, the development of new molecules with pharmacological potential is now an urgent matter. The biological activities of metal complexes have been reported to have antitumor, antimicrobial, anti-inflammatory, anti-infective and antiparasitic effects, amongst others. Metal complexes are effective because they possess unique properties. For example, the complex entity possesses the effective biological activity, then the formation of coordination bonds between the metal ions and ligands is controlled, metal ions provide it with extraordinary mechanisms of action because of characteristics such as d-orbitals, oxidation states, and specific orientations; metal complexes also exhibit good stability and good physicochemical properties such as water solubility. Platinum is a transition metal widely used in the design of drugs with antineoplastic activities; however, platinum is associated with side effects which have made it necessary to search for, and design, novel complexes based on other metals. Copper is a biometal which is found in living systems; it is now used in the design of metal complexes with biological activities that have demonstrated antitumoral, antimicrobial and anti-inflammatory effects, amongst others. In this review, we consider the open horizons of Cu(II)- and Pt(II)-based complexes, new trends in their design, their synthesis, their biological activities and their targets of action.

Polymer Lewis Base for Improving the Charge Transfer in Tin-Lead Mixed Perovskite Solar Cells.

The poor film stability of Sn-Pb mixed perovskite film and the mismatched interface energy levels pose significant challenges in enhancing the efficiency of tin-lead (Sn-Pb) mixed perovskite solar cells. In this study, polyvinylpyrrolidone (PVP) is introduced into the PVK perovskite precursor solution, effectively enhancing the overall stability of the film. This improvement is achieved through the formation of robust coordination bonds between the carbonyl (C=O) in the pyrrole ring and the undercoordinated SnII and PbII, thereby facilitating the passivation of defects. Furthermore, the introduction of PVP inhibits the oxidation of tin (Sn), thereby enhancing the n-type characteristics of the perovskite film. This adjustment in the energy level of the PVK perovskite film proves instrumental in reducing interface energy loss, subsequently improving interface charge transfer and mitigating device recombination. Consequently, perovskite solar cells incorporating PVP achieve an outstanding champion power conversion efficiency (PCE) of 21.31%.

Interferometric fiber sensor for lead ion detection based on MoS2 hydrogel coating

A fiber optic sensor coated with molybdenum disulfide (MoS2) hydrogel is firstly proposed for the detection of lead ion (Pb2+). By splicing a dispersion-compensating fiber (DCF) between two single-mode fibers (SMFs) to form a Mach-Zehnder interferometer (MZI), and using a fusion splicer to discharge the SMF input and output to form a thick waist cone to act as a coupler. A portion of the DCF cladding is etched to excite higher order cladding patterns and a hydrogel sensing film is applied to the etched area, the sulfur atoms in the sensing film form coordination bonds with Pb2+ and change the refractive index (RI) of the sensing film, which further leads to the wavelength shift of the resonant dip. The production process is simple and environmentally friendly. By monitoring the wavelength shift, the adsorption of Pb2+ is continuously monitored, and the sensor has a sensitivity of 3.25 × 108 nm/(mol/L) in the range of 0–1.1 × 10−8 mol/L Pb2+ in aqueous solution. The theoretical detection limit of Pb2+ concentration is 6.15 × 10−11 mol/L at a spectrometer resolution of 0.02 nm. In addition, the experimental results show that the sensor has good repeatability, selectivity and stability, and has a broad application prospect in the field of Pb2+ detection in industry and agriculture.

Bio‐inspired acid‐sensitive polyurethane woven artificial muscle nanofibers with tunable mechanical properties via electrostatic spinning

AbstractPolyurethane (PU) is a traditional chemical known for its chemical stability and mechanical performance. Inspired by the similarity between the formation and breakage of chemical coordination bonds and the energy storage and release of muscle fibers, muscle‐like electrostatically spun fibers with acid‐responsive energy storage and release were prepared by introducing bio‐inspired elastic energy storage groups and bio‐active degradation groups (PU‐BPY‐Fe) in the main chain of PU, taking advantage of the good mechanical properties of PU. The fabricated electrospinning film PU‐BPY‐Fe can respond to external stimulation, which generated high strain (32 MPa), stretch of 206%, outperforming the nanofiber membrane before stimulation, similar and even higher than the biological muscles. The variable mechanical properties and elastic energy storage capacity of PU‐BPY‐Fe were attributed to the reversible hydrogen bonding and the destabilization of metal coordination bonds (Fe3+ to Fe2+) within the material under acidic stimulation. Cytotoxicity testing of the synthesized fibers indicated a degree of biocompatibility, suggesting potential for in vivo applications. This method of storing and releasing elastic energy was demonstrated and has endowed the PU‐BPY‐Fe with stimuli‐responsibility and muscle‐like mechanical properties, which may inspire the design of soft muscles materials for robots and tissue engineering applications.

Purification, Characterization, cDNA Cloning, and Bioinformatic Analysis of Zinc-Binding Protein from Magallana hongkongensis.

Oysters contain significant amounts of the zinc element, which may also be found in their proteins. In this study, a novel zinc-binding protein was purified from the mantle of the oyster Magallana hongkongensis using two kinds of gel filtration chromatograms. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that its molecular weight was approximately 36 kDa. The protein identified by the Q-Exactive mass spectrometer shared the highest sequence identity with carbonic anhydrase derived from Crassostrea gigas concerning amino acid sequence similarity. Based on homologous cloning and RACE PCR, the full-length cDNA of carbonic anhydrase from Magallana hongkongensis (designated as MhCA) was cloned and sequenced. The cDNA of MhCA encodes a 315-amino-acid protein with 89.74% homology to carbonic anhydrase derived from Crassostrea gigas. Molecular docking revealed that the two zinc ions primarily form coordination bonds with histidine residues in the MhCA protein. These results strongly suggest that MhCA is a novel zinc-binding protein in Magallana hongkongensis.

Role of tea polyphenols in enhancing the performance, sustainability, and catalytic cleaning capability of membrane separation for water-soluble pollutant removal

Tea polyphenols (TPs), like green tea polyphenol (GTP) and black tea polyphenol (BTP), with phenolic hydroxyl structures, form coordination and hydrogen bonds, making them effective for bridging inorganic catalysts and membranes. Here, TPs were employed as interface agents for the preparation of TPs-modified needle-clustered NiCo-layered double hydroxide/graphene oxide membranes (NiCo-LDH-TPs/GO). The incorporation of porous guest material, NiCo-LDH-TPs, facilitated water channel expansion, enhancing membrane permeability and resulting in the development of high-performance, sustainable catalytic cleaning membranes. The introduction of TPs through coordination weakened the surface electronegativity of NiCo-LDH, promoting a uniform mixed dispersion with GO and facilitating membrane self-assembly. NiCo-LDH-GTP/GO-5 and NiCo-LDH-BTP/GO-5 membranes demonstrated permeances of 85.98 and 90.76 L m−2 h−1 bar−1, respectively, with rejections of 98.73% and 99.54% for methylene blue (MB). Notably, the NiCo-LDH-BTP/GO-5 membrane maintained a high rejection of 97.11% even after 18 cycles in the catalytic cleaning process. Furthermore, the modification of GTP and BTP enhanced MB degradation through PMS activation, resulting in a 0.33% and 0.35% increase in the reaction rate constants of NiCo-LDH, respectively, while reducing metal ion spillover. These findings highlighted the potential of TPs in enhancing the efficiency and sustainability of catalytic cleaning GO membranes for water purification and separation processes.

Organic Synthesis through Radical Innovation: Frustrated Radical Pairs†

AbstractFrustrated Lewis Pairs (FLPs) represent a unique class of interactions in Lewis acid‐base chemistry, driven by spatial hindrance or incongruent orbital energy levels that hinder the formation of effective coordination bonds. FLPs have received significant attention for their application in activating small molecules and facilitating organic synthesis reactions. Recent developments have led to the emergence of Frustrated Radical Pairs (FRPs) as an extension of the radical family. FRPs are formed from FLPs through Single Electron Transfer (SET) and exhibit the ability to activate a variety of chemical bonds. While research on FLPs is well‐established, investigations into FRPs in organic reactions remain limited. This review highlights the current state of FRPs in organic synthesis, delves into mechanistic insights, explores their potential, and underscores the challenges in this emerging field.

MOFs Modulate Copper Trafficking in Tumor Cells for Bioorthogonal Therapy.

In situ drug synthesis using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has attracted considerable attention in tumor therapy because of its satisfactory effectiveness and reduced side-effects. However, the exogenous addition of copper catalysts can cause cytotoxicity and has hampered biomedical applications in vivo. Here, we design and synthesize a metal-organic framework (MOF) to mimic copper chaperone, which can selectively modulate copper trafficking for bioorthogonal synthesis with no need of exogenous addition of copper catalysts. Like copper chaperones, the prepared ZIF-8 copper chaperone mimics specifically bind copper ions through the formation of coordination bonds. Moreover, the copper is unloaded under the acidic environment due to the dissipation of the coordination interactions between metal ions and ligands. In this way, the cancer cell-targeted copper chaperone mimics can selectively transport copper ions into cells. Regulation of intracellular copper trafficking may inspire constructing bioorthogonal catalysis system with reduced metal cytotoxicity in live cells.

Spectroscopic Investigation of Coumarin Based Novel Fluorescent TURN OFF Sensor for the Selective Detection of Fe3+: In-vitro Live Cell Imaging Application.

The novel TURN-OFF fluorescent sensors 4-(Benzo[1,3]dioxol-5-yloxymethyl)-7-hydroxy-chromen-2-one (4BHC) and 4-(6-Bromo-benzo[1,3]dioxol-5-yloxymethyl)-7-hydroxy-chromen-2-one (4BBHC) are designed and synthesized for the spectrofluorometric detection of the biologically important Fe3+ ions, which has sensitive and selective fluorescence quenching over other competitive metal ions. The effectiveness of the sensors and rapid response are validated through UV-Visible, and fluorescence spectral changes. These spectral changes could be due to the formation of coordination bond between ligand and metal ion. The binding stoichiometry of both sensors with Fe3+ ions is studied with the help of Job's plot, which gives a 1:2 coordination ratio; this is further confirmed through DFT, IR and NMR studies. The association constants of 4BHC and 4BBHC are calculated through Benesie-Hildebrand plots, and they are found to be 6 × 104M-1 and 11.2 × 104M-1 respectively. Following, LOD is calculated to define the range of sensitivity of the proposed sensors and is found to be 3.43μM and 2.14μM respectively. The chemical hardness parameter suggested that both sensors are soft molecules. In addition, low cytotoxicity levels of 4BHC and 4BBHC led to the demonstration of their efficacy in In-Vitro imaging of Fe3+ ions inside living cells, which ensures that these sensors are promising candidates for bioimaging.