Unique Zn2 Research Articles

Tunneling Proton Grotthuss Transfer Channels by Hydrophilic-Zincophobic Heterointerface Shielding for High-Performance Zn-MnO2 Batteries.

Hollandite-type manganese dioxide (α-MnO2) is recognized as a promising cathode material upon high-performance aqueous zinc-ion batteries (ZIBs) owing to the high theoretical capacities, high working potentials, unique Zn2+/H+ co-insertion chemistry, and environmental friendliness. However, its practical applications limited by Zn2+ accommodation, where the strong coulombic interaction and sluggish kinetics cause significant lattice deformation, fast capacity degradation, insufficient rate capability, and undesired interface degradation. It remains challenging to accurately modulate H+ intercalation while suppressing Zn2+ insertion for better lattice stability and electrochemical kinetics. Herein, proton Grotthuss transfer channels are first tunneled by shielding MnO2 with hydrophilic-zincophobic heterointerface, fulfilling the H+-dominating diffusion with the state-of-the-art ZIBs performance. Local atomic structure and theoretical simulation confirm that surface-engineered α-MnO2 affords to the synergy of Mn electron t2g-eg activation, oxygen vacancy enrichment, selective H+ Grotthuss transfer, and accelerated desolvation kinetics. Consequently, fortified α-MnO2 achieves prominent low current density cycle stability (≈100% capacity retention at 1C after 400 cycles), remarkable long-lifespan cycling performance (98% capacity retention at 20C after 12000 cycles), and ultrafast rate performance (up to 30C). The study exemplifies a new approach of heterointerface engineering for regulation of H+-dominating Grotthuss transfer and lattice stabilization in α-MnO2 toward reliable ZIBs.

Electrolyte pH and operating potential: critical factors regulating the anodic oxidation and zinc storage mechanisms in aqueous zinc ion battery

The complicated multi-electron reactions and electrochemical/chemical evolution of vanadium oxides in zinc ion batteries make the detailed reaction mechanism difficult to understand. Here, we show that these reactions can be easily interpreted from the reliable potential–V-species (electrochemical) and pH–V-species (chemical) relationships. A systematic investigation of several low-valence vanadium oxides (V6O13, VO2, and V2O3) is conducted to study the detailed reaction mechanisms upon the anodic oxidation and routine zinc storage process. Vanadium oxides are thermodynamically converted to layered zinc pyrovanadate Zn3V2O7(OH)2·2H2O (ZVOH) in a certain range of pH (4.0–8.5) and operating potential following the VOx oxidation →V-species dissolution →ZVOH precipitation processes. The establishment of pH–V-species and potential–V-species relationships can well explain the reaction mechanisms not only in anodic oxidation but also in routine zinc insertion/extraction processes with the combination of electrochemical and chemical reactions. Moreover, due to the favorable open and stable crystal framework and unique Zn2+ storage mechanism, the obtained ZVOH exhibits a highly improved capacity of 492.7 mAh/g within the voltage window of 0.3–1.4 V. Our work highlights the critical roles of operating potential and electrolyte pH in zinc ion battery and offers new knowledge and practices for its commercialization.

Highly reversible zinc metal anode enabled by zinc fluoroborate salt-based hydrous organic electrolyte

Although Zn(BF4)2 contains favorable ingredients of fluorine for the formation of ZnF2 rich-Zn2+ ion conducting solid electrolyte interface (SEI), the aqueous electrolyte based on inorganic Zn salt of Zn(BF4)2⋅xH2O shows high Hammett acidity with pH value <1, which gives rise to severe corrosion of metallic Zn electrode and thermodynamically spontaneous hydrogen evolution reaction (HER). Meanwhile, an uneven and arbitrarily aggregated SEI will result in uneven distribution of Zn2+ ion flux and electric field, leading to rampant dendrite growth. Here, we employ a hydrophilic organic solvent of vinylene carbonate (VC) and hydrate Zn(BF4)2⋅4H2O salt for a hydrous organic electrolyte, denoted as ZnBF-VC. With the ZnBF-VC electrolyte used, the VC molecules preferably adsorb on the Zn surface to block H2O molecules and Zn metals. Meanwhile, the unique Zn2+-solvation sheath of Zn(VC)2.89(H2O)1.28(BF4)1.83 is formed, which forms an organic/inorganic hybrid SEI in-situ with ZnF2 and ZnCO3 as inorganic species. The distinct SEI enables favorable Zn2+ ion transport and can effectively protect metallic Zn electrode from corrosion, side reactions and dendrite formation. Consequently, the ZnǀǀZn cells cycled over 2200 h at 0.5 mA cm−2 and the ZnǀǀCu asymmetric cells maintained an excellent Coulombic efficiency (CE) of ∼99.7% over 550 cycles at 1 mA cm−2. Whereas, the ZnǀǀZn cells broke after only 74 cycles in aqueous electrolyte. Additionally, the full cell we assembled with manganese hexacyanoferrate (MnHCF) in ZnBF-VC electrolyte demonstrates excellent cycling stability, achieving a high specific capacity of 146.2 mAh g − 1, and a high retention rate of 85.3% over 1300 cycles at 0.4 A g − 1, while the cell using the referred ZnBF-H2O electrolyte survived only ∼6 cycles. This work proposes a feasible direction for the study of Zn(BF4)2-based organic electrolyte for Zn batteries.

Interfacial synthesis of strongly-coupled δ-MnO2/MXene heteronanosheets for stable zinc ion batteries with Zn2+-exclusive storage mechanism

Low-cost and nontoxic manganese dioxide (MnO2) cathodes have shown promising application in high-capacity and high-voltage rechargeable zinc ion batteries (ZIBs), but suffer from limited cycling life and energy density mainly due to poor electrical conductivity and structural failure induced by manganese dissolution and H+/Zn2+ co-intercalation in traditional aqueous electrolytes. Herein, two-dimensional strongly-coupled δ-MnO2/MXene heteronanosheets are efficiently developed for high-performance ZIBs, which mainly includes an in-situ polymerization of dopamine on Ti3C2 MXene surface and subsequent redox reaction between KMnO4 and polydopamine. Benefited from the conductive MXene nanosheets for fast electron transfer, and the thin thickness of δ-MnO2 nanosheets for improved Zn2+ insertion kinetics and structural stability, the δ-MnO2/MXene heteronanosheets exhibit unique Zn2+-exclusive storage mechanism without proton storage induced disadvantages (e.g., Mn dissolution in traditional aqueous electrolytes) and superior zinc storage performance in 0.5 M zinc triflate in triethyl phosphate organic electrolyte (Zn(OTf)2/TEP), offering a capacity of ∼163 mAh g−1 at 100 mA g−1, a high capacity retention of 84.5 % after 1000 cycles, and an areal capacity of 1.9 mAh cm−2 when the mass loading is up to 10.5 mg cm−2. This work provides unique Zn2+-exclusive storage mechanism of δ-MnO2 in organic electrolyte and opens up a new approach for building high-performance ZIBs.

Controllable Modulation of Efficient Phosphorescence Through Dynamic Metal‐Ligand Coordination for Reversible Anti‐Counterfeiting Printing of Thermal Development

AbstractDynamically tunable room‐temperature phosphorescence (RTP) organic materials have attracted considerable attention in recent years due to their great potential over a wide variety of advanced applications. However, the precise regulation of the intersystem crossing (ISC) process for efficient RTP materials with dynamically modulated properties in a rigid environment is challenging. Herein, an effective strategy for RTP material preparation with controllably regulated properties is developed via the construction of dynamic metal‐ligand coordination in a host‐guest doped system. The coordination interaction promotes ISC and phosphorescence emission of the guest, thus allowing the modulation of the photophysical properties of doped materials by changing the doping ratio and Zn2+ counterions. By taking advantage of the reversible metal‐ligand coordination interaction, the coordination‐activated, and dissociation‐deactivated RTP is dynamically manipulated. With the unique Zn2+‐responsible RTP enhancement materials, the anti‐counterfeiting applications of thermal development, and color inversion have been constructed for inkjet printing of high‐resolution patterns with high reversibility for many write/erase cycles. The results show that dynamic metal‐ligand coordination strategy is a promising approach for achieving efficient RTP materials with controllably modulated properties.

Redistributing zinc-ion flux by constructing a hybrid conductor interface for dendrite-free zinc anode

Rechargeable aqueous zinc-metal batteries have attracted soaring attention as alternative to conventional lithium-ion batteries for energy storage systems due to the high safety, low cost, and environmental benignancy. However, the spontaneous side reaction and dendrite growth lead to the poor electrochemical performance as well as serious safety issues. Herein, a multifunctional layer composed of zinc alginate (ZA) and vermiculite sheets (VS) is coating on zinc foil surface to simultaneously suppress the side reaction and dendrite growth. Unique Zn2+ channels built by ZA polymer and VS endow the ZAVS film with high zinc-ion transference number (tZn2+ = 0.81), which can both improve the migration of Zn2+ and redistribute the Zn2+ flux on the electrode surface. Consequently, dendrite growth is obviously inhibited. In addition, ZAVS film can serves as a buffer layer to isolate zinc anode from aqueous electrolyte, alleviating the zinc corrosion and hydrogen generation. Benefiting from the inhibition of dendrite growth and side reaction, superior electrochemical performance can be achieved as evidenced by the high Coulombic efficiency of 99.18% for 520 cycles, and ultra-long cycling stability over 1000 h with small voltage hysteresis. The construction of ZAVS artificial layer could be a promising strategy for advanced RAZMBs.

Bidirectional Interface Protection of a Concentrated Electrolyte, Enabling High-Voltage and Long-Life Aqueous Zn Hybrid-Ion Batteries.

Prussian blue analogues (PBAs) as a promising high-voltage cathode material for aqueous zinc-ion batteries (ZIBs) are usually subjected to an ephemeral lifespan and low Coulombic efficiency due to the irreversible phase change and high Zn2+ insertion potential. Besides, Zn dendrites, H2 evolution reaction, and corrosion derived from a Zn anode interface remain huge challenges. Given this, a highly stable zinc hexacyanoferrate (KZnHCF) cathode together with a mixed concentrated electrolyte is prepared to realize a high-voltage and long-life aqueous ZIB, in which the mixed concentrated electrolyte consisting of 30 m KFSI + 1 m Zn(CF3SO3)2 possesses a unique Zn2+ solvation sheath (Zn(CF3SO3)0.3(FSI)3.1(H2O)2.6) that can not only stabilize the cathode interface and improve the Coulombic efficiency but also fundamentally solve the Zn anode interface issues. As a result, the aqueous KZnHCF/Zn battery achieves an ultralong life over 3000 cycles without any capacity decay even under a high discharge voltage of 1.78 V (vs Zn2+/Zn). Such extraordinary performance represents significant progress in aqueous PBA-based ZIBs. This work shares guidance to improve the performance of aqueous ZIBs through optimizing the electrolyte in tuning the stable operation of the cathode and the zinc anode.

Reshaping the electrolyte structure and interface chemistry for stable aqueous zinc batteries

Metallic zinc (Zn) with high safety and low cost is an ideal anode for aqueous batteries, but suffers from water-induced side reactions and dendrite growth. Herein, we significantly stabilize the Zn anode in a non-concentrated aqueous zinc trifluoromethanesulfonate (Zn(OTF)2) electrolyte when 1,2-dimethoxyethane (DME) additive is used to simultaneously regulate the electrolyte structure and Zn interface chemistry. We find that the introduction of DME not only interrupts the original hydrogen-bond network of water but also creates a unique Zn2+-solvation structure with the co-participation of DME and OTF−, which restrains the water-induced parasitic reactions. The in-situ formation of an organic-inorganic hybrid ZnF2-ZnS-rich interphase on Zn derived by the decomposition of DME and OTF− can suppress water penetration onto Zn and homogenize Zn2+ plating. In addition, DME molecules preferentially adsorb on the Zn surface, preventing the random growth of Zn dendrites. This novel H2O+DME electrolyte enables Zn anodes to achieve unprecedented cycling stability (over 5000 h at 2.0 mA cm−2) and high reversibility (99.7% Coulombic efficiency over 800 cycles). The efficacy of DME additives is further demonstrated in Zn//V2O5•nH2O full batteries with both coin- and pouch-type configurations. This work will inspire the design of efficient electrolytes for stable aqueous batteries.

Synthesis of chiral ND-322, ND-364 and ND-364 derivatives as selective inhibitors of human gelatinase

Compounds 10 (ND-322) and 15 (ND-364) are potent selective inhibitors for gelatinases, matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9). However, both of them are racemates. Herein we report facile synthesis of optically active (R)- and (S)-enantiomers of compounds 10 and 15. And the sulfonyl of 15 was transformed to sulfinyl to obtain four epimeric mixtures. All synthesized thiirane-based compounds were evaluated in MMP2 and MMP9 inhibitory assays. Our results indicated that the configuration of thiirane moiety had little effects on gelatinase inhibition, but the substitution of sulfinyl for sulfonyl was detrimental to gelatinase inhibition. Besides, all target compounds exhibited no inhibition against other two Zn2+ dependant metalloproteases, aminopeptidase N (APN) and histone deacetylases (HDACs), which confirmed the unique Zn2+ chelation mechanism of thiirane moiety against gelatinases.

Clioquinol, a lipophilic Zn2+ chelator, augments and attenuates the cytotoxicity of H2O2: a bell-shaped response curve of the effects of the drug

Clioquinol, a lipophilic Zn2+ chelator, has emerged as a potential novel therapeutic agent for several diseases such as cancer and Alzheimer's disease. Clioquinol has different effects on the intracellular Zn2+ concentrations in rat thymocytes, depending on its concentration and extracellular Zn2+ levels. In this study, we examined the effect of clioquinol on cells under oxidative stress induced by hydrogen peroxide (H2O2) by using a conventional flow cytometric technique with appropriate fluorescent probes. We observed a bell-shaped relationship between the clioquinol concentration and changes in H2O2 cytotoxicity; H2O2-induced cytotoxicity was the highest at a clioquinol concentration of 100 nM. Zn2+ chelators significantly decreased the clioquinol-induced increase in H2O2 cytotoxicity. A bell-shaped curve was observed between the increase in H2O2-induced cytotoxicity by clioquinol and the intracellular Zn2+ concentrations, although the maximal increases in Zn2+ levels were induced by 300 nM clioquinol. In addition, clioquinol at concentrations ≥100 nM exerted antioxidant activity by decreasing the cellular oxidant levels. Thus, clioquinol can exert pro-oxidant or antioxidant effects, depending on its concentration and the extracellular concentration of Zn2+. Because of the unique Zn2+-dependent effects and toxicological profile of clioquinol, clioquinol should be considered for clinical use. Clioquinol, a lipophilic Zn2+ chelator, has emerged as a potential novel therapeutic agent for several diseases such as cancer and Alzheimer's disease.

Zinc networks: the cell-specific compartmentalization of zinc for specialized functions

Zinc (Zn2+) is the most abundant trace element in cells and is essential for a vast number of catalytic, structural, and regulatory processes. Mounting evidence indicates that like calcium (Ca2+), intracellular Zn2+ pools are redistributed for specific cellular functions. This occurs through the regulation of 24 Zn2+ transporters whose localization and expression is tissue and cell specific. We propose that the complement and regulation of Zn2+ transporters expressed within a given cell type reflects the function of the cell itself and comprises a 'Zn2+ network.' Importantly, increasing information implicates perturbations in the Zn2+ network with metabolic consequences and disease. Herein, we discuss our current understanding of Zn2+ transporters from the perspective of a Zn2+ network in four specific tissues with unique Zn2+ requirements (mammary gland, prostate, pancreas, and brain). Delineating the entire Zn2+ transporting network within the context of unique cellular Zn2+ needs is important in identifying critical gaps in our knowledge and improving our understanding of the consequences of Zn2+ dysregulation in human health and disease.

Novel Zn2+ Coordination by the Regulatory N-Terminus Metal Binding Domain of Arabidopsis thaliana Zn2+-ATPase HMA2

Arabidopsis thaliana HMA2 is a Zn2+ transporting P1B-type ATPase required for maintaining plant metal homeostasis. HMA2 and all eukaryote Zn2+-ATPases have unique conserved N- and C-terminal sequences that differentiate them from other P1B-type ATPases. Homology modeling and structural comparison by circular dichroism indicate that the 75 amino acid long HMA2 N-terminus shares the betaalphabetabetaalpha folding present in most P1B-type ATPase N-terminal metal binding domains (N-MBDs). However, the characteristic metal binding sequence CysXXCys is replaced by Cys17CysXXGlu21, a sequence present in all plant Zn2+-ATPases. The isolated HMA2 N-MBD fragment binds a single Zn2+ (Kd 0.18 microM), Cd2+ (Kd 0.27 microM), or, with less affinity, Cu+ (Kd 13 microM). Mutagenesis studies indicate that Cys17, Cys18, and Glu21 participate in Zn2+ and Cd2+ coordination, while Cys17 and Glu21, but not Cys18, are required for Cu+ binding. Interestingly, the Glu21Cys mutation that generates a CysCysXXCys site is unable to bind Zn2+ or Cd2+ but it binds Cu+ with affinity (Kd 1 microM) higher than wild type N-MBD. Truncated HMA2 lacking the N-MBD showed reduced ATPase activity without significant changes in metal binding to transmembrane metal binding sites. Likewise, ATPase activity of HMA2 carrying mutations Cys17Ala, Cys18Ala, and Glu21Ala/Cys was also reduced but showed a metal dependence similar to the wild type enzyme. These observations suggest that plant Zn2+-ATPase N-MBDs have a folding and function similar to Cu+-ATPase N-MBDs. However, the unique Zn2+ coordination via two thiols and a carboxyl group provides selective binding of the activating metals to these regulatory domains. Metal binding through these side chains, although found in different sequences, appears as a common feature of both bacterial and eukaryotic Zn2+-ATPase N-MBDs.

The first dinuclear zinc(II) dithiocarbamate complex with butyl substituent groups

The crystal structure of the title compound, bis(μ-N,N-di­butyl­di­thio­carbamato-κ2S:S′)­bis­[(N,N-di­butyl­di­thio­carbamato-κ2S,S′)­zinc(II)], [Zn2(C9H18NS2)4], has been determined at 180 K. The structure contains two crystallographically unique Zn2+ metal centres, showing almost identical slightly distorted tetrahedral coordination environments, and forming a dinuclear complex with two skew-bridging syn-N,N-di­butyl­di­thio­carbamate ligands. Two other di­thio­carbamate ligands are connected to the Zn2+ centres in a syn,syn-chelate coordination mode.

A Human RNA Viral Cysteine Proteinase That Depends upon a Unique Zn2+-binding Finger Connecting the Two Domains of a Papain-like Fold

A cysteine proteinase, papain-like proteinase (PL1pro), of the human coronavirus 229E (HCoV) regulates the expression of the replicase polyproteins, pp1a and ppa1ab, by cleavage between Gly111 and Asn112, far upstream of its own catalytic residue Cys1054. In this report, using bioinformatics tools, we predict that, unlike its distant cellular homologues, HCoV PL1pro and its coronaviral relatives have a poorly conserved Zn2+ finger connecting the left and right hand domains of a papain-like fold. Optical emission spectrometry has been used to confirm the presence of Zn2+ in a purified and proteolytically active form of the HCoV PL1pro fused with theEscherichia coli maltose-binding protein. In denaturation/renaturation experiments using the recombinant protein, its activity was shown to be strongly dependent upon Zn2+, which could be partly substituted by Co2+ during renaturation. The reconstituted, Zn2+-containing PL1pro was not sensitive to 1,10-phenanthroline, and the Zn2+-depleted protein was not reactivated by adding Zn2+ after renaturation. Consistent with the proposed essential structural role of Zn2+, PL1pro was selectively inactivated by mutations in the Zn2+ finger, including replacements of any of four conserved Cys residues predicted to co-ordinate Zn2+. The unique domain organization of HCoV PL1pro provides a potential framework for regulatory processes and may be indicative of a nonproteolytic activity of this enzyme.

Regulation of tumour necrosis factor-alpha processing by a metalloproteinase inhibitor.

Tumour necrosis factor-alpha (TNF-alpha) is a potent pro-inflammatory agent produced primarily by activated monocytes and macrophages. TNF-alpha is synthesized as a precursor protein of M(r) 26,000 (26K) which is processed to a secreted 17K mature form by cleavage of an Ala-Val bond between residues 76-77. The enzyme(s) responsible for processing pro-TNF-alpha has yet to be identified. Here, we describe the capacity of a metalloproteinase inhibitor, GI 129471, to block TNF-alpha secretion both in vitro and in vivo. The inhibition is specific to TNF-alpha; the production of other secreted cytokines, such as the interleukins IL-1 beta, IL-2, or IL-6, is not inhibited. The mechanism of inhibition occurs at a post-translational step in TNF-alpha production. Our data suggest that TNF-alpha processing is mediated by a unique Zn2+ endopeptidase which is inhibited by GI 129471 and would represent a novel target for therapeutic intervention in TNF-alpha associated pathologies.