Metal Ion Coordination Research Articles

Cu/MOF-808 Catalyst for Transfer Hydrogenation of 5-Hydroxymethylfurfural to 2, 5-Furandimethanol with Formic Acid Mediation

Biomass platform compound 5-Hydroxymethylfurfural (HMF), with its low price and abundant source, can be used as a renewable resource to replace traditional petrochemicals. MOF-808(Zr) has tunable active sites and excellent stability under high temperatures and acidic as well as basic environments, and the unsaturated coordination of metal ions within its framework structure can exhibit Lewis acidity, facilitating catalytic transfer hydrogenation from HMF to 2, 5-Furandimethanol (BHMF). The hydrothermal–impregnation–reduction method was used to prepare Cu/MOF-808 catalysts with high catalytic performance. Formic acid was chosen as the hydrogen donor solvent. The selectivity and yield of BHMF were 75.65% and 71%, respectively, at 150 °C for 4 h. A reaction pathway for the catalytic hydrogen transfer of HMF to BHMF was proposed. The high activity and stability of the Cu/MOF-808 catalyst with dual active sites provide a viable method for feasible hydrogenation of HMF to high value-added compounds.

Energetics and Dynamics of Metal-Ion Coordination with Ionic Liquid Electrolytes: A Combined DFT and AIMD Investigation for Rechargeable Batteries

Energetics and Dynamics of Metal-Ion Coordination with Ionic Liquid Electrolytes: A Combined DFT and AIMD Investigation for Rechargeable Batteries

In Situ Preparation of MnO2 on the Catechol/Silane-Coated Polypropylene Nonwoven Fabrics for Effective Removal of Cationic Dyes.

Previous studies have confirmed that MnOx removes heavy metal ions and organic pollutants from water with dual effects of adsorption and oxidation coupling, significantly improving the ability to remove impurities. Nanometal oxides have a highly reactive surface but tend to agglomerate during preparation and are challenging to recycle after use. A common method is to combine nano-MnO2 with Fe3O4 to prepare magnetic materials for easy recycling. Our previous research has confirmed that catechol (CA) and (3-aminopropyl) triethoxysilane (KH550) can be co-deposited on the surface of polypropylene nonwovens to form a stable CK coating under alkaline conditions. In addition, the coating has many active groups, including hydroxyl groups, amino groups, etc. This study further investigates the secondary reactivity of CK coatings. The coordination of catechol groups and metal ions was used to anchor manganese ions to the coating. Meanwhile, the hydroxyl and amino groups were used to reduce manganese ions to Mn4+ in situ to prepare PP-(CK-MnO2). We found that the sample had an excellent decolorization effect on cationic dyes but was limited to anionic dyes. The decolorization mechanism of cationic dyes was further discussed. The results showed that the decolorization of cationic dyes had a dual effect of adsorption and oxidative degradation. Under acidic conditions, its oxidation properties were enhanced. It can be used as a highly effective decolorizing agent for cationic dyes, and the decolorization behavior is consistent with the first-order kinetics. As the pH increases, its oxidation properties gradually decrease. Although the electrostatic adsorption effect was enhanced, the overall decolorization performance was significantly reduced. Recycling experiments have proved that it can maintain >90% removal rate after five cycles. This study also demonstrated that the CK coating has dopamine-like properties, which can coordinate with metal ions to prepare metal-organic hybrid materials.

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

A smartphone-integrated bimetallic ratiometric fluorescent probe for specific visual detection of tetracycline antibiotics in food samples and latent fingerprinting

Designing and preparing highly sensitive and accurate fluorescent chemosensors for monitoring tetracycline antibiotics remains a challenge. Herein, a fluorescent chemosensor based on lanthanide metal-organic frameworks (Ln-MOFs) is proposed to realize high-precision monitoring by adjusting the ratio of lanthanide ions. Ln-MOFs with good aqueous stability were prepared by a solvothermal method using Eu3+, Tb3+ and the ligand 4,4′,4″-s-triazine-2,4,6-triyltribenzoic acid (H3TATB) in DMF/NMP/H2O. The Ln-MOFs could recognize oxytetracycline (OTC) and doxycycline (DOX), and the detection limits of OTC and DOX were as low as 8.6 and 4.8 nM, respectively. In particular, Eu(1.4 μM)-Tb-MOF sensors were used for visual detection of OTC and DOX in combination with smartphones with detection lines as low as 9.8 nM and 14.2 nM, respectively. Meanwhile, Eu-MOF, Tb-MOF and Eu(1.4 μM)-Tb-MOF can be used for latent fingerprint (LFP) visualization, demonstrating their potential applications in the field of criminal case investigation. The developed probes were successfully applied to determining OTC and DOX in milk, beef and pork with recoveries ranging from 92.0 % to 109.63 % and relative standard deviations (RSDs) ranging from 1.83 % to 4.56 %. Eu(1.4 μM)-Tb-MOF is believed to utilize its lanthanide metal ion coordination and photoinduced electron transfer (PET) mechanism to achieve highly selective and accurate OTC and DOX detection, which is supported by experimental and density functional theory (DFT) calculations.

Coordination-driven molecular switch on the base of an ESIPT-capable pyrimidine ligand: Synthesis, fine-tuning of emission by the halide anion and theoretical studies

ESIPT-based materials (ESIPT = Excited State Intramolecular Proton Transfer) find diverse applications in optoelectronics and biomedicine owing to the peculiarities of their luminescence properties. Here, an ESIPT-capable compound 2-(3,5-dimethyl-1H-pyrazol-1-yl)-4-(2-hydroxyphenyl)pyrimidine (HL4,2,Me) featuring a short O–H⋅⋅⋅N intramolecular hydrogen bond and two N,N-sites for metal binding has been synthesized. HL4,2,Me is the first reported molecule which can act as an ESIPT molecular switch triggered by metal ion coordination without its deprotonation. Drastic changes in the HL4,2,Me conformation in the [Zn(HL4,2,Me)X2] (X = Cl, Br,I) complexes significantly alter the photoluminescence response compared to the free ligand. In the solid state, HL4,2,Me exhibits barrierless ESIPT and large Stokes-shifted yellow-orange emission due to the interplay of anti-Kasha S2 → S0 fluorescence and Kasha-like T1 → S0 phosphorescence radiative channels. The violation of Kasha’s rule for HL4,2,Me is justified by an extraordinarily large S2 – S1 energy gap (ca. 0.9 eV), slowing down the rate of S2 → S1 internal conversion. The photoluminescence behavior of the ESIPT–incapable zinc(II) coordination compounds strongly depends on the halide anion: the chlorido complex exhibits only fluorescence, the bromido complex displays a minor phosphorescence channel in addition to a major fluorescence channel, while the iodido complex exhibits predominantly phosphorescence. As a result, the emission color of the [Zn(HL4,2,Me)X2] complexes changes gradually from blue for X = Cl to orange for X = I, providing a platform for the fine-tuning of emission by the halide anion.

Synthesis of Sm‐TADDbBP@MCM‐41 as a Robust, Reusable, and Practical Nanocatalyst in the Homoselective [2 + 3] Cycloaddition Reaction

ABSTRACTSchiff‐base materials are known ligands for the coordination of metal ions and the synthesis of various stable and useful complexes. Therefore, herein, a novel Schiff‐base compound {2,2′‐((1E,11E)‐2,5,8,11‐tetra azadodeca‐1,11‐diene‐1,12‐diyl) bis (4‐bromophenol)} was introduced that formed from condensation of triethylenetetramine (TETA) and 5‐bromo‐2‐hydroxybenzaldehyde (5B2HB). This Schiff‐base ligand was labeled as TADDbBP. Besides, mesoporous MCM‐41 was synthesized using tetraethyl orthosilicate (TEOS), hydrolyzing cetyltrimethylammonium bromide (CTAB) and NaOH solution (2 M), followed by calcination at 550 °C, and further, the silanol sites on the MCM‐41's surface were modified by 3‐chloropropyltriethoxysilane (3Cl‐PTES), which modified MCM‐41 was labeled as 3‐Cl‐Pr@MCM‐41. In the next step, the synthesized TADDbBP (as Schiff‐base ligand) was grafted on 3‐Cl‐Pr@MCM‐41, which was labeled as TADDbBP@MCM‐41, and further, it was coordinated with samarium ions (which was labeled as Sm‐TADDbBP@MCM‐41 nanocatalyst) using Sm (CH3COO)3. This is the first report on the production of Sm‐TADDbBP@MCM‐41 nanocatalyst, this nanocatalyst was characterized by TEM, SEM, EDX, elemental mapping, BET method, ICP, XRD, and TGA techniques. In the final step, the catalytic performance of Sm‐TADDbBP@MCM‐41 nanocatalyst has been checked in the homo‐selective producing of tetrazoles through [2 + 3] cycloaddition of benzonitriles and sodium azide (NaN3) in PEG‐400 as available, nontoxic, green, and safe solvent. This nanocatalyst provides excellent selectivity in the synthesis of tetrazoles. In addition, Sm‐TADDbBP@MCM‐41 nanocatalyst can be separated and recycled for several cycles without significant reactivation or metal leaching.

Development of Recoverable Magnetic Bimetallic ZIF-67 (Co/Cu) Adsorbent and Its Enhanced Selective Adsorption of Organic Dyes in Wastewater.

In the critical domain of wastewater treatment, the development of cost-effective, durable, and recyclable adsorbents with high adsorption capacities remains a significant challenge. This study introduces a novel magnetic bimetallic Metal-Organic Framework (MOF) adsorbent, MZIF-67-Co/Cu, doped with copper ions. The MZIF-67-Co/Cu adsorbent was successfully synthesized and structurally characterized, demonstrating remarkable selectivity for removing methyl orange (MO) from water. This high selectivity is attributed to the adsorbent's high porosity and Lewis base properties at the coordinating metal ion center. The incorporation of Cu ions significantly enhances the porous architecture and increases the number of metal adsorption sites, leading to an impressive maximum MO adsorption capacity of 39.02 mg/g under optimized conditions (0.5 g/L adsorbent concentration, pH 3.0, 250 rpm agitation speed, adsorption time > 10 min). The adsorption kinetics closely follow the pseudo-second-order model, and the isotherm data fit well with the Langmuir model. The primary adsorption mechanisms involve electrostatic attraction and mesoporous interaction. This study highlights MZIF-67-Co/Cu as a highly efficient adsorbent with magnetic recovery capabilities, positioning it as a promising candidate for addressing critical issues in wastewater treatment.

The influence of Fe2+ on the self-assembly of a bipyridine containing homopolymer: From bowl-shaped nanoparticles to vesicles

Metal ion coordination has critical influence on the self-assembly behavior of amphiphilic polymers and the morphology of the obtained assemblies. Herein, an amphiphilic homopolymer with 2,2′-bipyridine (BPy) as side chain is synthesized (noted as PBPyAA), which can self-assemble into bowl-shaped nanoparticles (BNPs) in tetrahydrofuran (THF)/water. Taking advantage of the coordination interaction between BPy and metal ions, Fe2+ is chosen to regulate the self-assembly behavior and the morphology of the assemblies of PBPyAA in two pathways. (Ⅰ) The aqueous solution of Fe2+ with various concentrations is added to the THF solution of PBPyAA during self-assembly. (Ⅱ) Fe2+ is added into the THF solution of PBPyAA before self-assembly, followed by the addition of deionized water to promote the self-assembly. The results show that the pathway Ⅰ facilitates the coordination of BPy and Fe2+. With the increase of the concentration of Fe2+ aqueous solution, the coordination efficiency of BPy increases from 0.419 % to 7.789 %, leading to the transformation of BNPs to vesicles. Though the coordination efficiency of BPy also increases with the concentration of Fe2+ in pathway Ⅱ, which is still quite low of 0.274 % to 0.366 %, and the morphology of the BNPs barely changes. In addition, ethylene diamine tetraacetic acid (EDTA), a strong chelating agent, is also added to promote the competitive complexation with BPy, resulting in the dissociation of BPy and Fe2+ and the reversible transformation from vesicles to BNPs. Overall, the effect of Fe2+ coordination on the self-assembly behavior of PBPyAA in two pathways is investigated and the reversible transformation of BNPs to vesicles is also achieved.

Construction of One-Dimensional Covalent-Organic Framework Coordinated with Main Group Metals for Selective Electrochemical Synthesis of H2O2.

Covalent-organic frameworks (COFs) are promising electrocatalysts for the selective synthesis of H2O2 through the two-electron oxygen reduction reaction (2e- ORR). However, the design and synthesis of efficient and stable COF-based electrocatalysts is still challenging. In this work, a predesigned 1,10-phenanthroline-based one-dimensional COF (PYTA-PTDE-COF) was constructed to anchor main group metal (In, Sn, and Sb) as electrocatalysts toward 2e- ORR. The catalysts are featured with fully exposed metalated side chains. Structural characterization revealed that PYTA-PTDE-M's (M = In, Sn, and Sb) are all quite similar, except for the coordinated metal ions with the maintenance of good crystallinity. They all exhibited satisfying activity and selectivity toward 2e- ORR under alkaline conditions. Among them, PYTA-PTDE-Sb exhibited the best performance (Eonset is 0.765 V, the H2O2 selectivity is 96%, and the yield rate is 209.2 mmol gcat-1 h-1). Moreover, it also delivered superior stability with almost no attenuation of current density during the long-time test. Theoretical calculations revealed that the Sb metal site in the COFs has the lowest adsorption strength of *OOH, which could be the main reason for its superior selectivity. The PYTA-PTDE-Sb assembled zinc-air battery realizes not only the supply of clean energy but also the production of green chemicals, showing it is highly promising in practical applications. This work offers an example for designing main group metal-coordinated 1D COFs and reveals fundamental structure-activity relationship toward 2e- ORR.

Probing the Closed Association of Oligoquinoline Foldamers by Time-Resolved Fluorescence Anisotropy.

The metal-mediated dimerization of oligoquinoline foldamers terminated at one end with an oligo(phenylenevinylene) and at the other with a carboxylic acid (OPV-QnA, where n = 4, 8, 17, and 33), and the complexation of OPV-Q8A and Q16A was promoted in chloroform by the addition of a concentrated 16 M aqueous sodium hydroxide solution. UV-vis absorption and time-resolved fluorescence anisotropy (TRFA) experiments were conducted to determine, respectively, the concentration and the average rotational time ⟨ϕ⟩ of the mixture of unassociated and associated foldamers across a range of foldamer concentrations spanning 5 orders of magnitude. Plots of ⟨ϕ⟩ as a function of acid group concentration revealed that ⟨ϕ⟩ increased with increasing foldamer concentration only when the foldamer solution in chloroform was vigorously mixed with the 16 M sodium hydroxide aqueous solution. Furthermore, all plots showed that ⟨ϕ⟩ reached a plateau at high foldamer concentration. The increase in ⟨ϕ⟩ reflected the association of foldamers into larger objects through metal ion coordination with the carboxylate anions generated by deprotonation of the carboxylic acid of OPV-QnA with NaOH, while the plateau obtained at high foldamer concentration indicated that these interactions led to the dimerization of the foldamers via a closed association mechanism. Analysis of the ⟨ϕ⟩ trends yielded the equilibrium constants (K) describing the foldamer dimerization, whose value equaled 1.0 (±0.2) × 106 M-1 for the three longer OPV-QnA foldamers, but was about 10 times smaller for the shortest one (n = 4). Association of OPV-Q8A and Q16A yielded a complex with a ⟨ϕ⟩ matching that of OPV-Q24A, and K for this complexation was similar to that for dimerization. These experiments illustrate the robust nature of TRFA as an experimental method to probe the size of rigid, self-assembled foldamers in solution.

Metal‐Organic Cages: Synthetic Strategies and Photocatalytic Application

AbstractMetal‐organic cages (MOCs) are a class of compounds formed through the coordination of metal ions with organic ligands to create well‐defined and cage‐like structure. These unique structures offer versatile environments for catalyzing a wide range of chemical reactions. The catalytic capabilities of MOCs are significantly influenced by the nature of the metal ions, functional ligands, and the cage structure. Notably, the confined spaces within MOCs can lead to enhanced reaction efficiencies, particularly in processes such as light‐induced hydrogen generation and the photocatalytic reduction of CO₂. Furthermore, MOCs show great potential in photo‐organic synthesis due to the cage structure, which provides a confined environment and allows for encapsulating organic molecules, making them useful for improving the selectivity and efficiency of catalytic process. This review reports the development of MOCs for photocatalysis, focusing on the structural design and regulation strategy to build functional MOCs for photocatalytic hydrogen production, CO2 reduction, organic transformation. Insights into the photocatalysis are discussed including the challenges and further research direction in MOC‐based photocatalysis.

Bioinorganic Chemistry Meets Microbiology: Copper(II) and Zinc(II) Complexes Doing the Cha-Cha with the C-t-CCL-28 Peptide, Dancing till the End of Microbes.

The necessity to move away from conventional antibiotic therapy has sparked interest in antimicrobial peptides (AMPs). One fascinating example is human CCL-28 chemokine produced by acinar epithelial cells in the salivary glands. It can also be released into the oral cavity with saliva, playing a crucial role in oral protection. The C-terminal domain of CCL-28 possesses antifungal and antibacterial properties, which are likely linked to membrane disruption and enzyme leakage. Studies suggest that AMPs can become more potent after they have bound Cu(II) or Zn(II). In many cases, these ions are essential for maximizing effectiveness by altering the peptides' physicochemical properties, such as their local charge or structure. The examined peptide binds Cu(II) and Zn(II) ions very effectively, forming equimolar complexes. Metal ion binding affinity, coordination mode, and antimicrobial activity strongly depend on the pH of the environment. Coordination modes have been proposed based on the results of potentiometric titrations, spectroscopic studies (UV-visible, electron paramagnetic resonance and circular dichroism at different path lengths), and mass spectrometry. The antimicrobial properties of the Cu(II) and Zn(II) complexes with the C-terminal fragment of CCL-28 chemokine have been assessed against fungal and bacterial strains, demonstrating exceptional activity against Candida albicans at pH 5.4. Moreover, the complex with Zn(II) ions shows the same activity against theStreptococcus mutans bacterium as chloramphenicol, a commonly used antibiotic. Cyclic voltammetry proposed a probable antimicrobial mechanism of the studied Cu(II) complex through the formation of reactive oxygen species, which was also confirmed by tests with ascorbic acid in UV-vis and fluorescence spectroscopic studies.

AKTIVITAS ANTIBAKTERI KURKUMIN DAN KOMPLEKS TEMBAGA (II) KURKUMIN TERHADAP S.AUREUS DAN E.COLI

Copper (II) complex of curcumin was prepared from the reaction between curcumin and a metal precursor (CuCl2.2H2O) in ethanol with a mole ratio curcumin to metal 2:1. The FTIR spectrum of Cu2+-curcumin shows a change in the absorption band and a shift in the wave number, especially in the absorption band of the phenolic –OH group 3510.45 cm-1 which is a stretching vibration that becomes wider and shifts to a larger wave number, namely 3514.30 cm-1. Compared with free curcumin spectrum the absorption band of the C=O functional group shows a change where in free curcumin is at 1627.92 cm-1 while in the Cu2+-curcumin complex the is at 1735.93 cm-1 this indicate the coordination of metal ions with curcumin. The IR spectrum shows a typical absorption band for the metal oxygen group, Cu-O 480.28 cm-1 in the Cu2+-curcumin complex. The UV-Vis spectrum of the Cu2+-curcumin complex show a shift towards a larger wavelength (red shift/batochromic) of (~2 nm). Antibacterial activity of Cu2+-curcumin complex compound is active in inhibiting S.aureus and E.coli. After complexation, the activity against the tested microorganisms generally increased and the complex showed higher activity than free curcumin.

GSH responsive AuNRs@TFF nanotheranostic for NIR-II photoacoustic imaging-guided CDT/PTT synergistic cancer therapy

Gold nanorods (AuNRs) are important photothermal therapeutic agents; however, a single therapy does not achieve satisfactory outcomes, and the synthesis process often leads to the adsorption of cetyltrimethylammonium bromide on the surface of AuNRs, which reduces its biocompatibility. Natural polyphenols are abundant in natural plants and have good biocompatibility. The metal-polyphenol network is formed by the coordination of metal ions and polyphenols, which has good drug loading, surface adhesion, and biocompatibility. In this study, the metal-polyphenol network structure formed by a transition metal (iron) and natural polyphenol tannic acid was used to modify the surface of gold nanorods (AuNRs@TF). Additionally, the surfaces of AuNRs were modified using the targeted functional molecule mercapto folic acid (AuNRs@TFF). The constructed composite nanomaterials AuNRs@TFF has good biocompatibility and tumor targeting ability. Tannic acid‑iron degrades in the tumor microenvironment and releases iron ions that catalyze the Fenton reaction, thereby facilitating chemodynamic therapy. The good photo-thermal ability of AuNRs generate good photoacoustic signals to facilitate photoacoustic imaging mediation and enhances photothermal and chemodynamic therapy performance. This study expands on the application of AuNRs in the field of nanomedicine. The simple and effective design of AuNRs@TFF provides a strategy for the development of synergistic therapeutic agents for photothermal therapy and chemodynamic therapy.

Synthesis of Quinone‐Amine‐Linked Covalent Organic Frameworks for Boosting the Photocatalytic Removal of Uranium

AbstractCompared to imine covalent organic frameworks (COFs), the superior stability of amine‐linked COFs renders them more suitable for long‐term harsh real‐world environments. Their numerous amine sites can serve as functional groups or be subjected to post‐modification to further enhance the performance of the material. However, the assortment and abundance of amine‐linked COFs via currently lacking due to restricted monomer varieties and synthetic methods. Herein, this study presents an innovative approach for synthesizing quinone‐amine‐linked COFs by directly combining 2,5‐dihydroxy‐1,4‐benzoquinone (DHBQ) with various amine monomers and introduce a novel photocatalyst, DHBQ‐TAPP‐COF, specifically tailored to efficiently reduce uranium in harsh environments. DHBQ‐TAPP‐COF features a unique donor–acceptor structure, with the DHBQ units serving as acceptors because they contain abundant oxygen atoms that facilitate metal ion coordination, thereby enhancing charge carrier separation, carrier utilization, and uranium reduction efficiency. The quinone‐amine linkages offer improved stability, extended π‐conjugation, heightened local polarity, and conductivity, which enable efficient carrier transfer within the material and thus enhance the overall performance of the uranium photocatalyst. The proposed photocatalyst can efficiently reduce U(VI) without sacrificial agents or decomposition to precipitate UO2 at a recovery rate exceeding 98%. This catalyst provides an efficient and convenient strategy for the stable and high‐performance photocatalytic reduction of uranium.

Why Colloidal Syntheses of Bimetallic Nanoparticles Cannot be Generalized.

Introducing one general synthesis to form bimetallic nanoparticles (NPs) could accelerate the discovery of NPs for promising energy applications. Although colloidal syntheses can provide precise structural and morphological control of bimetallic NPs, the complex chemical nature of multicomponent syntheses challenges the realization of such synthetic simplicity. Common synthetic issues are frequently ascribed to the variation in metal ion precursor reactivities and complex chemical interactions between the different metal surfaces and capping agents employed. However, no systematic studies have shown how these factors compete to ultimately assign the factor limiting the mixing and formation of bimetallic NPs. Here, we provide a parametric investigation of how the intrinsic standard reduction potentials (E0red) of the metal ions and cocapping agents influence the formation of bimetallic AuCu, AuPd, and PdCu NPs. Using a combination of in situ X-ray total scattering along with transmission electron microscopy and nuclear magnetic resonance spectroscopy, we illustrate the multifunctional role of the cocapping agents through interactions with both the metal ion precursors and NP surfaces to stabilize metastable structures. Additionally, we demonstrate how system-specific side reactions and the local metal ion coordination environment can be used to selectively tune the formation kinetics, structure, and morphology of bimetallic NPs. Ultimately, these insights show that the chemical interactions rather than the intrinsic E0red are responsible for the formation of bimetallic NPs. Broadly, these insights should aid the synthetic design of tailored multimetallic NPs.

Self‐Assembled Bioinspired Short Metallopeptide Nanostructures for Plausible Biomedical Applications

AbstractMetal chelation, characterized by its precise interactions with diverse functional groups, assumes a pivotal role in providing structural stability and generating reactive centers within metalloproteins and metallopeptides. This, in turn, orchestrates the architecture and functionality of various biological processes in living organisms. In our biomimetic approach inspired by the intricacies of natural metallopeptides, we have purposefully designed pyridine‐bis‐tyrosine, a concise Metallopeptide Conjugate (sMPC). Demonstrating the capacity to form complexes with various bioactive metal ions, sMPC emerges as a promising tool for advancing our understanding of metal‐binding proteins and catalyzing the development of cutting‐edge biotechnological materials and technologies. Our investigations underscore the hierarchical self‐assembly of these abridged conjugates into toroidal to vesicle nanostructures, influenced by concentration, and their susceptibility to spatial manipulation through metal ion coordination with functional groups. These biocompatible metal peptide complexes and their resultant nanomaterials present specific potential as exceptional therapeutic agents to address problems associated with metal ion deficiencies, offering a facile and low‐cost alternative to traditional metallodrugs.

Coordination Behaviors between Aryl Diamide Amine Ligands and Trivalent Lanthanides: A Spectroscopic and Structural Study

Investigating the complexation of organic ligands with trivalent lanthanides (Ln(III)) is crucial in various fields, particularly in the separation of actinides from lanthanides for spent fuel reprocessing. While alkyl diamide amine ligands have been extensively studied, aryl‐functionalized ligands are rarely reported. To understand the effect of substituents on the coordination mode of diamide amine ligands with Ln(III), two aryl‐substituted diamide amine ligands, 2,2'‐(p‐tolylazanediyl)bis(N‐ethyl‐N‐(p‐tolyl)acetamide) (L1) and 2,2'‐((2‐ethylhexyl)azanediyl)bis(N‐ethyl‐N‐(p‐tolyl)acetamide) (L2), were synthesized and systematically studied. 1H NMR titration showed that metal ion coordination affected the electron density of methylene groups near coordinating atoms more than that of aromatic rings, while fluorescence titration and single‐crystal analysis confirmed 1:1 ligand‐Ln(III) complexes. Compared to alkyl diamide amine ligands, aryl groups increased steric hindrance, enhancing torsional strain and preventing amine nitrogen from participating in complexation, leading to weaker coordination as only two carbonyl oxygen atoms coordinated with Ln(III) in a bidentate mode. This work provides insight into how substituents influence the complexation properties of diamide amine ligands with f‐elements, aiding in the design of new ligands with improved performance.

Modulating the isomerization of bpp-modified azoheteroarene by transition metal ions coordination

A new photoswitchable azoheteroarene L was design and synthesized by replacing one of the phenyl rings of azobenzene moiety with a 2,6-di[pyrazol-1-yl]pyridine(bpp) unit. The assembly of L with transition metal ions results in the formation of three metal complexes, namely, M(L)2(OTf)2 (M=ZnII, FeII and CoII). These complexes are fully characterized by ESI-TOF-MS, UV–vis spectrum, 1H NMR spectrum and single-crystal X-ray diffraction. Upon irradiation with 380 nm light, L exhibits excellent E to Z photoisomerization in solution, achieving up to 82 % Z-configuration with a thermotropic isomerization half-life time of 301 days. After coordination with ZnII, FeII and CoII, the photoisomerization properties of L were significantly varied. Coordinating with the ZnII ion, the conversion of Z-L slightly decreased from 82 % to 77 %. However, this coordination significantly extends thermal isomerization half-life time to 564 days, resulting in a 1.9-fold enhancement compared to free Z-L. In contrast, the coordination with open-shell transition metal ions FeII and CoII noticeably inhibits the formation of Z-L and only yields E-L isomers. Moreover, the spin-crossover behavior of Fe(E-L)2(OTf)2 was also investigated. The analysis of variable temperature NMR indicates that Fe(E-L)2(OTf)2 shows a spin transition temperature of 265 K in solution. This work provides valuable insights into tunning conformational transitions of azoheteroarene molecules.