Central Cu2 Research Articles

Lysyl oxidase nanozyme-loaded hydrogel for sustained release and promotion of diabetic bone defect regeneration.

The process of regenerating bone injuries in diabetic presents significant challenges because lysine oxidase (LOX), a key catalytic enzyme for collagen cross-linking, is inhibited in hyperglycemia. The supplementation of LOX is constrained by inadequate sources and diminished enzymatic activity, necessitating the development of effective alternatives for enhancing bone regeneration in diabetes. Herein, we reported a lysyl oxidase nanozyme (LON), derived from the catalytic domain of LOX. LON formed a stable coordination structure with the active center Cu2+ through histidine imidazolyl nitrogen and quinone oxygen, which is consistent with the conformation of the LOX. Our findings suggested that LON demonstrated the capacity to substitute LOX in promoting collagen synthesis and biomineralization. To enable sustained LON delivery, it was incorporated into a GelMA hydrogel (GH), forming a sustained-release reservoir known as LON-GelMA hydrogel (LONGH). Mechanism of LONGH promoting bone healing to accelerate the crosslinking and maturation stage of collagen were also explored, and the 23 genes closely associated with collagen regeneration and osteogenesis were found to be upregulated. The present investigation outcomes reveal that the engineered LONGH hydrogel presents a novel, simple, and commercially viable approach for bone regeneration, offering significant potential for clinical applications.

Two-Dimensional π-d Conjugated Conductive Metal-Organic Framework with Triple Active Centers as High-Performance Cathodes for Flexible Zinc Batteries.

Conductive metal-organic frameworks (C-MOFs) have received extensive interest in high-performance zinc-ion batteries (ZIBs) owing to multi-redox sites and high electrical conductivity. Here, we present a π-d C-MOF by coordinating 2,3,5,6-tetraaminobenzoquinone (TABQ) ligands with Cu2+ ions (2D Cu-TABQ) acting as cathodes for ZIBs. Benefiting from a triple active center (Cu2+, C=O, and C=N), 2D Cu-TABQ shows an ultra-high reversible capacity of 297.7 mAh g-1 at 0.2 A g-1. Meanwhile, 2D Cu-TABQ also has superior cycle stability with a capacity of up to 98.2 mAh g-1 after 1000 times at 2.0 A g-1. Considering the instability of the ligand bonds of C-MOFs in aqueous electrolytes, this work uses gel electrolytes to reduce the dissolution of organic ligands into the electrolyte, thus suppressing the shuttle effect, significantly improving the cycling stability of 2D Cu-TABQ. The flexible battery assembled by 2D Cu-TABQ shows excellent capacity retention (64.4 %) after 50 times at 0.2 A g-1, which is significantly better than 36.4 % in the common electrolyte, as well as outstanding bending resistance and electrochemical properties at different folding angles. This investigation will highlight the electrochemical application of C-MOFs in flexible zinc ion batteries and offer novel ideas for the structural design of cathodes with multiple active centers.

Ion-selective supramolecular membrane with pH-regulated smart nanochannels for lithium extraction

Tunable gating ion-conducting membranes with high water permeability and precise ion selectivity remain urgently demanded in smart nanofiltration for efficient lithium extraction. Herein, inspired by the filtration function of protein channels, we report a smart and high-performance supramolecular membrane constructed via coordination between quaternary ammonium ligands (m-phenylenediamine/polyethyleneimine) and metal ion center (Cu2+). The pore architecture of the supramolecular membrane is dynamic and can be switched by applying pH stimulus, where coordinated interchain expands when exposed to acidic operating conditions and induces concomitantly reinforced electrostatic exclusion due to enhanced local charge density. The tunable gating regularity enables operando modulation of precise ionic separation in situ. The resulting membrane exhibits significantly enhanced water permeance (19.8 L m−2 h−1·bar−1) and simultaneously promoted Li+/Mg2+ selectivity (RMg2+ = 96.4 %), surpassing typical trade-off between permeability and selectivity at pH 3 condition. This study demonstrates the amazing capability of environmental-responsive regulation of membrane pore-channel structure, and provides inspiration for engineering advanced supramolecular membranes for lithium extraction and beyond.

Enhancing sulfur resistance of oxides in carbon monoxide oxidation by a high‐entropy‐stabilized strategy

AbstractIndustrial chemical processes require sulfur‐resistant catalysts, which reduce catalyst replacement costs and simplify process operations. Herein, a high‐entropy‐stabilized strategy was put forward for sulfur‐resistant catalysis. A spinel high entropy (Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4) was introduced by ball milling process with aluminum isopropoxide as the main precursor. Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4 possessed a high surface area of 171.2 m2 g−1, higher than typical high‐entropy oxides (HEOs). The high‐entropy spinel catalyst exhibited better SO2‐resistance performance in the oxidation of carbon monoxide, better than the simple oxides. The SO2‐resistance of Zn0.2Mg0.2Cu0.2Mn0.2Co0.2Al2O4 was primarily improved by reinforcing the stability of the oxide using a high‐entropy structure to decrease the absorption of SO2 on its surface. Any adsorbed SO2 on the surface of the HEO was then selectively trapped by sacrificial metal ions with stronger electron‐withdrawing ability, protecting the active center (Cu2+, Co2+) from poisoning. This work reveals the significance of high‐entropy structures in sulfur resistance.

Interfacially Modulated S‐Scheme Van der Waals Heterojunctional Photocatalyst for Selective CO2 Photoreduction Coupled with Organic Pollutant Degradation

This study introduces a novel strategy employing a phosphate‐mediated S‐scheme 2D/2D Van der Waals heterojunction, xCu[acs]/yP‐BCN, linking copper phthalocyanine (CuPc) with boron‐doped and nitrogen‐deficient graphitic carbon nitride (BCN). By leveraging phosphate as a charge transfer mediator, spatial constraints are mitigated, facilitating efficient electron transition from BCN to CuPc upon excitation. The captured photoelectrons by CuPc central Cu2+ ion promote CO2 conversion into valuable products, boosting photocatalytic efficiency by 78‐fold compared to standalone BCN. In situ µs transient absorption spectroscopy quantitatively demonstrates a remarkable 36.4% electron transfer efficiency for CO2 reduction with xCu[acs]/yP‐BCN, surpassing other catalyst configurations. Additionally, a 4% CuPc integration into BCN substantially increases photodegradation efficiency of methylene blue (MB) to 96%, attributed to the heterojunction's ability to prevent charge carrier recombination. Moreover, under direct sunlight, the optimized heterostructure achieves a bisphenol‐A (BPA) photodegradation efficiency of approximately 70.6%, highlighting the potential of interface‐tailored photocatalysts in efficiently reducing CO2 and degrading environmental pollutants.

Cleaving DNA with DNA: Cooperative Tuning of Structure and Reactivity Driven by Copper Ions.

A copper-dependent self-cleaving DNA (DNAzyme or deoyxyribozyme) previously isolated by in vitro selection has been analyzed by a combination of Molecular Dynamics (MD) simulations and advanced Electron Paramagnetic Resonance (Electron Spin Resonance) EPR/ESR spectroscopy, providing insights on the structural and mechanistic features of the cleavage reaction. The modeled 46-nucleotide deoxyribozyme in MD simulations forms duplex and triplex sub-structures that flank a highly conserved catalytic core. The DNA self-cleaving construct can also form a bimolecular complex that has a distinct substrate and enzyme domains. The highly dynamic structure combined with an oxidative site-specific cleavage of the substrate are two key-aspects to elucidate. By combining EPR/ESR spectroscopy with selectively isotopically labeled nucleotides it has been possible to overcome the major drawback related to the "metal-soup" scenario, also known as "super-stoichiometric" ratios of cofactors versus substrate, conventionally required for the DNA cleavage reaction within those nucleic acids-based enzymes. The focus on the endogenous paramagnetic center (Cu2+ ) here described paves the way for analysis on mixtures where several different cofactors are involved. Furthermore, the insertion of cleavage reaction within more complex architectures is now a realistic perspective towards the applicability of EPR/ESR spectroscopic studies.

Nano metal-photosensitizer based on Aza-BODIPY-Cu complex for CDT-enhanced dual phototherapy

Chemodynamic therapy (CDT) combined with dual phototherapy (photothermal therapy (PTT) and photodynamic therapy (PDT)) is an efficient way to synergistically improve anti-tumor efficacy. However, the combination of multiple modes often makes the composition of the system more complex, which is not conducive to clinical application. In this study, a dual phototherapy ligand carboxyl-modified Aza-BODIPY (BOD-COOH) and metal active center Cu2+ were used to construct multiple-modes metal-photosensitizer nanoparticles (BOD-Cu NPs) via one-step coordination self-assembly for combination therapy of CDT/PDT/PTT. In order to improve delivery efficiency, the targeted hydrophilic molecule pyridine-modified glucose derivative (G-Py) was synthesized and coated onto the BOD-Cu NPs to form a glycosylated nano metal-photosensitizer BOD-Cu@G by electrostatic interaction. The Cu2+ in BOD-Cu@G could not only be used as a coordination node for metal-driven self-assembly but also consume intracellular glutathione (GSH), and then catalyze Fenton-like reaction to generate hydroxyl radical (·OH) for CDT. In vitro and in vivo studies revealed that BOD-Cu@G could achieve excellent anti-tumor efficiency by CDT-enhanced dual phototherapy.

New copper(II) complexes with hydroxypyridines: Synthesis, structural, thermal, and magnetic properties

We have synthesized and characterized four new copper(II) complexes with 2-hydroxypyridine in its lactam tautomeric form (2-pydo) and 4-hydroxypyridine in both lactim (4-hpy) and lactam (2-pydo) tautomeric forms: [Cu2(µ-Ac)4(4-pydo)2]·2CH3CH (1), [Cu(Ac)2(4-hpy)2(H2O)] (2), [Cu(2-pydo)4(NO3)2] (3), and [Cu(4-pydo)2(NO3)(H2O)2]NO3 (4). The products were characterized structurally by single-crystal X-ray analysis and FT-IR spectroscopy. The complexes consist of five or six coordinated central Cu2+ ion with 4-pydo, 4-hpy, 2-pydo, acetate, nitrate, and water ligands. Magnetic measurements carried out between 2 and 300 K give the results of µeff ≈ 1.7 BM at room temperature, as expected for Cu2+. The thermal analysis showed that the final product, obtained by heating the title compounds to 600 °C in nitrogen, is nanosized elemental copper. The results are comparable to those reported in literature for analogous compounds.

Controllable synthesis of CuPc/N-rich doped (0 0 1) TiO2 S-scheme nanosheet heterojunctions for efficiently wide-visible light-driven CO2 reduction

Inspired by natural photosynthesis, the rational design of efficient S-scheme heterojunctions holds promises for CO2 conversion by utilizing solar light. Herein, nitrogen-rich doped 001-exposed anatase nanosheets (NPT) have been designed and fabricated by post-treatment with NH3 at a high temperature of 600 °C to phosphate modified TiO2 firstly, and then controllably coupled with copper phthalocyanine (CuPc) via a hydroxyl-induced assembly process to construct a wide-visible-light responsive heterojunction towards CO2 conversion. The optimized CuPc/NPT heterojunction achieves a high production rate of CO (∼5 μmol/g/h) under visible light irradiation, with ∼9-fold enhancement compared with generally N-doped TiO2. Based on the experimental results mainly from photocurrent action spectra, electron paramagnetic resonance measurements, electrochemical reduction curves and in-situ diffuse reflectance infrared Fourier transform spectra, it is confirmed that the exceptional photoactivity is attributed to the N-rich doping for increasing visible-light absorption of TiO2, the effective S-scheme charge transfer from the closely-contacted CuPc/NPT heterojunction with wide visible-light absorption, and subsequently to the electron transfer from the Pc ligand to central metal Cu2+ with good catalytic function for CO2 reduction. This work provides feasible routes for the design and preparation of TiO2-based photocatalysts for solar-driven CO2 conversion.

Experimental-Theoretical Approach for the Chemical Detection of Glyphosate and Its Potential Interferents Using a Copper Complex Fluorescent Probe

The present contribution proposes an optical method for the detection of glyphosate (GLY) using a Cu(II) bis-(oxamate) complex ([Cu(opba)]2−) as the fluorescent probe. It wa found that in acetonitrile solution, its fluorescence increases in the presence of GLY and scales linearly (R2 = 0.99) with GLY concentration in the range of 0.7 to 5.5 µM, which is far below that established by different international regulations. The probe is also selective to GLY in the presence of potential interferents, namely aminomethyl phosphonic acid and N-nitrosoglyphosate. Theoretical results obtained by time-dependent density functional theory coupled to a simplified treatment of the liquid environment by using a self-consistent reaction-field revealed that GLY molecules do not coordinate with the central Cu2+ ion of [Cu(opba)]2−; instead, they interact with its peripheral ligand through hydrogen bond formation. Thereby, GLY plays mainly the role of the proton donor. The results also suggest that GLY increases the dielectric constant of the medium when it contributes to the stabilization of the excited state of the [Cu(opba)]2− and enhancement of its fluorescence.

A theoretical study of structure properties and stability in different ligands coordinated Cu-MOFs

A comprehensively theoretical study of structural properties and thermostability is performed to investigate the role of ligands in Metal Organic Frameworks (MOFs). By fitting the experimental EPR spectra, the high order perturbation formulae of a 3 d9 ion in four Cu-MOFs with ligands btm, bte, btp and btb are adopted for orthorhombically and tetragonally elongated octahedral [CuO2N4]12− groups so as to reveal the local environment around central Cu2+, including the detail structure information and local electromagnetic properties. Since the application of MOFs are normally limited by the unsatisfied thermostability, the molecule dynamic (MD) calculation based on density functional theory (DFT) is performed to clarify the influence on the stability of MOFs from the different ligands. Based on the above investigations, the mechanism of ligands substitution in MOFs can be comprehensively understood, which would be useful for designing and synthesizing novel MOFs.

Exploring the Electronic Influence of β‐Br Substitutions in CuTPP on Electrochemical Overall Water Splitting in Alkaline Medium

AbstractBeta substitution has a marked influence on the electronic environment of porphyrin ring atoms and the structure of the substituted porphyrin. In this work, we explore the influence of the bromo (Br) substitution at the β‐positions of copper tetraphenylporphyrin (CuTPP) and its consequent influence on the electrocatalytic alkaline overall water splitting. The β‐Br substitution is expected to exercise a strong influence on the electronic environment of central Cu through the electronic effects of Br. The overall influence of electronic effects is seen to lead to the net increase in the electron density of the central Cu (observed from XPS shifts) which is ultimately reflected in their different HER and OER performance in the alkaline medium. We observe the HER overpotentials (for 10 mA cm−2) of 697 mV, 760 mV, 838 mV, and 883 mV for the unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The OER performance on the contrary depicts the reverse order with the overpotentials of 1118 mV, 827 mV, 637 mV, and 420 mV respectively for unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The observed shifts in the catalytic performance can directly be attributed to increasing charge density on the central metal Cu2+ with the increase in the number of Br groups which in turn has opposite consequences for HER and OER performance.

A new ternary copper (Ⅱ) complex of 2,4-dihydroxybenzoic acid: Synthesis, crystal structure and its catalytic decomposition effect on AP and RDX

In order to solve the unclear problems of structure and composition for 2,4-dihydroxybenzoic acid (2,4-DHBA) copper salt (β-Cu), a new insoluble ternary copper (Ⅱ) complex of 2,4-DHBA ([Cu(C12H8N2)2(C7H5O4)](C7H5O4)) was designed and synthesized in water. The ternary complex crystallizes in the monoclinic system with the space group P21/n. The central Cu2+ is coordinated with four nitrogen atoms from two 1,10-phenanthroline ligands and one carboxyl oxygen atom from a 2,4-DHBA anion. The other 2,4-DHBA anion does not participate in coordination and only provides the action of balance charge. In addition, compared with β-Cu, no water molecules exist in the ternary complex. The thermal stability of the ternary complex was investigated, as well as its catalytic decomposition activity on AP and RDX. With the addition of the ternary complex, the exothermic decomposition peak temperatures of AP and RDX were reduced from 406.5 to 353.9 ​°C, and 242.3 to 181.4 ​°C respectively, and the apparent activation energies were reduced from 293.1 to 207.4 ​kJ ​mol−1, and 239.6 to 177.5 ​kJ ​mol−1, respectively. Moreover, the addition of the ternary complex has greatly improved the heat release of AP and RDX. The catalytic decomposition performance of the new ternary complex on AP and RDX is much better than that of the traditional β-Cu. Moreover, the new copper (Ⅱ) complex completely changed the thermal decomposition process of RDX from melting decomposition to direct solid phase decomposition, and such catalytic effect is uncommon. Therefore, the new ternary copper (Ⅱ) complex presents a better potential application for modified double-base propellant of RDX.

Effect of SrO and TeO2 on the physical and spectral properties of strontium tellurite boro-titanate glasses doped with Cu2+ ions

A new glass series of strontium tellurite boro-titanate glasses doped with Cu2+ ions were prepared with the composition (30-x)SrO-xTeO2–10TiO2–59B2O3–1CuO [STTBC] (where x = 5,4,3,2&1 mol%) using the melt quenching technique. The effect of varying the mol% of SrO and TeO2 on the physical and spectroscopic properties were investigated. XRD, SEM, EDS, UV–VIS, EPR and FTIR analysis were carried out to observe changes in the STTBC glass structure. From the optical absorption data the cut-off wave length, the optical band gap, Urbach energy values, etc., were calculated. The electron paramagnetic resonance (EPR) spectra (experimental & theoretical) of these glasses were extensively studied by deriving the spin-Hamiltonian parameters, bonding coefficients, paramagnetic susceptibility and crystal-field parameters etc. The higher order perturbation approach is employed to study the interaction between the ligand and the central Cu2+ ion.

Au-Modulated Z-Scheme CuPc/BiVO4 Nanosheet Heterojunctions toward Efficient CO2 Conversion under Wide-Visible-Light Irradiation

Unraveling the sluggish charge separation, insufficient catalytic sites, and limited visible-light absorption for Z-scheme heterojunction photocatalysts still remains a great challenge toward CO2 conversion. Herein, ultrafine Au-modulated copper phthalocyanine/BiVO4 nanosheet heterojunctions (CuPc/Au-BVNS) with wide-visible-light responses have been successfully fabricated as efficient photocatalysts for CO2 conversion to CO, achieving 9-time and 35-time photoactivity improvement compared to pristine BVNS (ca. 5 nm) and the previously reported BiVO4 nanoflake (ca. 15 nm), respectively. The exceptional photoactivity is mainly attributed to the ultrafine Au interfacial modulation, which is well capable of inducing the directional electron migration of BVNS and the highly dispersed CuPc assembly with the increased loading amount, synergistically strengthening the Z-scheme charge transfer and separation mainly based on the surface photovoltage spectroscopy assisted with the monochromatic beam and electron paramagnetic resonance technique. Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy, CO2 temperature-programmed desorption measurement, and electrochemical results demonstrate that the central metal Cu2+ in the high-dispersion CuPc exhibits potential catalytic functions for CO2 reduction, much superior to other metals in MPc (M = Co and Ni)-modified ones. This work highlights the importance of strengthening artificial Z-scheme charge transfer and provides new strategies for designing BiVO4-based heterojunctions by controllably assembling MPc toward efficient solar-driven CO2 conversion.

Perovskite surface management by thiol and amine copper porphyrin for stable and clean solar cells

The leakage of noxious lead and the instability of perovskite film induced by interfacial defects have impeded the practical application of perovskite solar cells (PSCs). Here, we develop a perovskite surface management strategy by the post-treatment with a copper porphyrin containing thiol and secondary amine group (Cu-Por). The thiol-terminal in Cu-Por can coordinate with the Pb defects on the perovskite surface. The central Cu2+ ions in Cu-Por tune the electron distribution within porphyrin ring, thereby effectively binding the I− and I2 on the perovskite surface by π-I interaction and the hydrogen-bonds between the side chain N–H group with I− and I2. Finally, the Cu-Por-treated PSCs gave the best efficiency of 21.24%. More importantly, the modified device maintained over 90% of its initial efficiency under AM 1.5G illumination or heated at 85 °C in N2 atmosphere after 2000 h. Especially, the Cu-Por treated PSCs can prevent the leakage of lead. This finding provides a new perovskite surface management strategy to fabricate the stable and clean PSCs.

Syntheses, structures and magnetic behaviors of 1D and 3D µ1,5-dicyanamide bridged copper(II) coordination polymers containing a symmetrical 1,2-diamine as a chelator

Two neutral copper(II) coordination polymers, [Cu(en)(µ1,5-dca)(dca)]n (1) and [Cu3(en)2(µ1,5-dca)6]n (2) [en = 1,2-ethanediamine, dca = dicyanamide], with µ1,5-dicyanamide bridges have been isolated. X-ray structural analysis reveals that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of the symmetrical 1,2-ethanediamine (en) ligand, one nitrile N atom of a terminal dca ligand and two nitrile N atoms of the μ1,5 bridging dca ligand. 1 is an example of coordination polymer containing both μ1,5-dca and terminal dca. Adjacent copper atoms are connected by dca ligands in the μ1,5-bridging mode affording a 1D chain structure. In the crystalline state, these 1D chains are further associated through weak intermolecular NH⋯N hydrogen bonds to form a 2D sheet structure, viewed along the crystallographic b axis. The asymmetric unit of 2 contains two types of copper(II) centers (Cu1 and Cu2). Cu1 adopts a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the bidentate ligand (en) and three nitrile N atoms of three different μ1,5 bridged dca ligands, whereas Cu2 is connected to six nitrile atoms of six different μ1,5 bridged dca ligands, resulting in a distorted octahedral geometry with a CuN6 chromophore. Adjacent copper atoms are connected by μ1,5-bridging dca ligands to form a 3D network coordination polymer structure, which contains multiple NH∙∙∙N hydrogen bonds in the crystalline state. A variable-temperature magnetic susceptibility study shows very weak antiferromagnetic interactions among the neighboring metal centers through the μ1,5-dca bridges with J = −0.12 cm−1 for complex 1 and J = −0.19 cm−1 for complex 2.

Cathodic electrodeposited Cu-BTC MOFs assembled from Cu(II) and trimesic acid for electrochemical determination of bisphenol A.

The authors describe a novel electrochemical determination method for bisphenol A (BPA) based on the electrosynthesised Cu-BTC (H3BTC: trimesic acid) films. Using H3BTC as the ligand, Cu(NO3)2 as the precursor of copper ions, and triethylamine hydrochloride (Et3NHCl) as the probase source, Cu-BTC films were directly deposited on glassy carbon electrode (GCE) surface via cathodic electrochemical reduction under -1.30V. Considering the electrocatalytic activity of metal center Cu2+, Cu-BTC films were applied to construct the electrochemical determination platform for BPA. Chronocoulometry and electrochemical impedance spectroscopy were used to study the signal enhancement mechanism. The determination conditions were optimized. As a result, a sensitive electrochemical method was constructed for BPA. The peak currents, best measured at voltage of 0.496V vs. SCE (KCl saturated calomel reference electrode), increase linearly in the range from 5.0 to 2000nM. The value of determination limit is 0.72nM. The proposed method was successfully applied to determine BPA in spiked urine, spiked waste water samples and plastic products. The results were in good agreement with those obtained for the same samples by high-performance liquid chromatography (HPLC). Graphical abstract Schematics for the construction of electrochemical determination for bisphenol A.

1-AminoTriazole Transition-Metal Complexes as Laser-Ignitable and Lead-Free Primary Explosives.

This unique complex study describes two isomeric aminotriazoles as auspicious nitrogen-rich ligands for energetic coordination compounds (ECCs) to replace the commonly used highly poisonous and environmentally harmful lead-based primary explosives. The triazoles were obtained by easily scalable and convenient synthetic routes starting solely from commercially available starting materials. 1-Amino-1,2,3-triazole (1, 1-ATRI) and, for the first time, 1-amino-1,2,4-triazole (2, 1A-1,2,4-TRI) were employed as ligands to form highly energetic transition-metal(II) complexes. The desired characteristics could be altered successively by using various nonpoisonous metal(II) centers (Cu2+ , Mn2+ , Fe2+ , and Zn2+ ) and anions (Cl- , NO3 - , ClO3 - , ClO4 - , picrate, styphnate, 2,4,6-trinitro-3-hydroxyphenolate, and 2,4,6-trinitro-3,5-dihydroxyphenolate). The 14 synthesized coordination compounds were characterized comprehensively by XRD, IR and UV/Vis spectroscopy, elemental analysis, and differential thermal and thermogravimetric analyses. Ball-drop impact, electrostatic discharge (ESD), and mechanical (impact and friction) sensitivities were determined according to BAM standard methods. In addition to laser ignition experiments, selected ECCs were evaluated in classical secondary explosive initiation tests (detonators filled with pentaerythritol tetranitrate (nitropenta)), which revealed their enormous potential and proved them to be very attractive for future applications in explosives.

Dielectric relaxation in pure and doped with Cu lead germanate single crystal

Dielectric permittivity of pure and doped with copper lead germanate Pb5Ge3O11 (PGO) crystal was studied in wide frequency (20 Hz to 3 GHz) and temperature (120 K to 450 K) range. The ferroelectric phase transition in PGO crystals is mixed “order-disoder” and displacive. Second order phase transition temperature shifts to lower temperature with increase the concentration of Cu2+ dopant. At low temperatures the dielectric relaxation caused by off center Cu2+ ion dynamics was detected. Dielectric dispersion in PGO:Cu crystals is attributed to domain wall dynamics and dipole glass freezing. It is shown that the domain relaxation requires lower energy then for the random freezing dipoles.