Transition Metal Ions Research Articles

Na3.5(MnVFeTi)0.5(PO4)3: A Multi‐Transition‐Metal‐Ion‐Engineered NASICON‐Type Cathodes for Sodium Ion Batteries

AbstractElectrochemically active Na‐superionic conductor (NASICON)‐type cathodes have the structural flexibility to include various transition elements, thus enabling high power outputs benefited by multi‐electron redox reactions. This study amalgamated multiple transition metal ions to construct a new NASICON‐type cathode i. e., carbon coated Na3.5(MnVFeTi)0.5(PO4)3 (NMVFTP/C) for Na‐ion batteries (NIBs). The NMVFTP/C cathode engineered in this study demonstrated stable Na+‐storage capacity, including long‐term cycling stability up to 4000 cycles at 3000 mA g−1 with 96 % capacity retention and a high‐rate output capacity of 85.16 mAh g−1 at 2500 mA g−1. To elucidate the ion transport process within the cathode, density functional theory modeling was employed. The low energy barrier for the diffusion of Na+ in the NMVFTP/C materials was proved to be a key factor supporting our material's superior electrochemical performances.

Complexes of Iron(II), Cobalt(II), and Nickel(II) with DOTA-Tetraglycinate for pH and Temperature Imaging Using Hyperfine Shifts of an Amide Moiety.

Paramagnetic complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA4-) derivatives have shown potential for molecular imaging with magnetic resonance. DOTA-tetraglycinate (DOTA-4AmC4-) coordinated with lanthanide metal ions (Ln3+) demonstrates pH/temperature sensing with Biosensor Imaging of Redundant Deviation in Shifts (BIRDS) and Chemical Exchange Saturation Transfer (CEST), respectively, detecting nonexchangeable (e.g., -CHy, where 3 ≥ y ≥ 1) and exchangeable (e.g., -OH or -NHx, where 2 ≥ x ≥ 1) protons. Herein, we report paramagnetic complexes of divalent transition-metal ions (M2+ = Fe2+, Co2+, Ni2+) with DOTA-4AmC4- that endow a unique amide proton (-NH) moiety for pH/temperature sensing. Crystallographic data reveal that DOTA-4AmC4- coordinates with M2+ through oxygen and nitrogen donor atoms, ranging in coordination numbers from 8-coordinate in Fe(II)DOTA-4AmC2-, 7-coordinate in Co(II)DOTA-4AmC2-, and 6-coordinate in Ni(II)DOTA-4AmC2-. The -CHy protons in M(II)DOTA-4AmC2- displayed modest pH/temperature sensitivities, but -NH protons exhibited higher intensity, suggesting prominent BIRDS properties. The pH sensitivity was the highest for Ni(II)DOTA-4AmC2- (1.42 ppm/pH), followed by Co(II)DOTA-4AmC2- (0.21 ppm/pH) and Fe(II)DOTA-4AmC2- (0.16 ppm/pH), whereas temperature sensitivities were comparable (i.e., 0.22, 0.13, and 0.17 ppm/°C, respectively). The CEST image contrast for -NH in M(II)DOTA-4AmC2- was much weaker compared to that of Ln(III)DOTA-4AmC-. Given its high pH sensitivity and low cytotoxicity, Ni(II)DOTA-4AmC2- shows promise for use in preclinical BIRDS-based pH imaging.

Cobalt(II) and Manganese(II) Complexes of Sodium Monensinate a Bearing Nitrate Co-Ligands

Monensic acid is a natural polyether ionophore and is a therapeutic of first choice in veterinary medicine for the control of coccidiosis. Although known as a sodium-binding ligand, it can also form a variety of coordination species depending on experimental conditions applied. In this study, we present the crystal structures and properties of Co(II) and Mn(II) complexes of sodium monensinate (MonNa) derived from the reaction of MonNa with cobalt or manganese dinitrates. The newly obtained coordination compounds have the same composition [M(MonNa)2(NO3)2] but the transition metal ions are placed in a different environment. The two nitrate ligands behave mono- or bidentately bound in the Co(II)- and Mn(II)-containing species, respectively, while the monensinate ligands act in a similar manner through their monodentate carboxylate functions. The formed CoO4 and MnO6 units determine the geometry of the corresponding inner coordination cores of the complexes as a tetrahedron in the case of Co(II), and as a strongly distorted octahedral structure in Mn(II) species. The effect of inorganic anions on the antibacterial performance of sodium monensinate appears to be negligible, while the presence of Co(II) or Mn(II) cations preserves or enhances the activity of unmodified MonNa, which differentially affects the growth of Bacillus subtilis, Bacillus cereus, Kocuria rhizophila, Staphilococcus aureus, and Staphilococcus saprophyticus strains.

Synergistic Interplay between Fe-based Perovskite Oxides and Co in Electrolyte for Efficient Oxygen Evolution Reaction.

Perovskite oxides have been extensively investigated as active electrocatalysts for the oxygen evolution reaction (OER) in alkaline solution. While the OER activity of some perovskite oxides is positively influenced by Fe ions in the electrolyte, the impact of other transition metal ions in the electrolyte remains unclear. In this study, we compared the influence of Co ions intentionally added to the electrolyte on the OER activities of two Fe-based perovskite oxides (Ba0.5Sr0.5FeO3-δ and LaFeO3). While the OER activity ofBa0.5Sr0.5FeO3-δis significantly enhanced by adding Co ions to the electrolyte, LaFeO3 showed little difference in the OER behavior between the Co-free and Co-containing electrolytes. In the case of Ba0.5Sr0.5FeO3-δ, an amorphous layer was formed, and the Co ions from the electrolyte were incorporated on the surface as a result of OER cycling. On the other hand, Co ions were also detected on the surface ofLaFeO3, but its crystalline structure remains unchanged during the OER. Our study suggests that synergistic interplay between the perovskite oxides undergoing a structural transformation at the surface and transition metal ions in the electrolyte can improve the OER activity.

Design of high-performance binary carbonate/hydroxide Ni-based supercapacitors for photo-storage systems

Silicon solar cells were used to convert solar energy into electrical energy, and a supercapacitor was designed to store this energy. To maximize the surface area of the electrodes, a three-dimensional Ni foam substrate was employed, onto which Ni-based compounds were deposited to enhance the electrochemical performance of the electrodes. Specifically, to address the conductivity reduction problem that arises when using only Ni ions, we introduced transition metal ions such as Mn, Co, Cu, Fe, and Zn to create binary compounds as electrode material. These binary metal compounds provided high electronic conductivity, structural stability, and reversible capacity, thereby optimizing the performance of the supercapacitor. As a result, the optimized NiCo(CO3)(OH)2 electrode demonstrated high capacity and excellent cycle stability, exhibiting an energy density of 35.5 Wh kg−1 and a power density of 2555.6 W kg−1 as an asymmetric supercapacitor device. Furthermore, when this device was combined directly with silicon solar cells, it achieved a storage efficiency of 63 % and an overall efficiency of 5.17 % under an illumination intensity of 10 mW cm−2. These findings suggest the potential for commercializing high-performance self-charging energy storage devices and contribute significantly to the advancement of energy storage technology.

Exact-Two-Component Complete Active Space Method with Variational Treatment of Magnetic Field and Spin-Orbit Coupling: Application to X-ray Magnetic Circular Dichroism Spectroscopy.

We introduce an exact-two-component complete active space self-consistent-field (X2C-CASSCF) method formulated under the restricted-magnetic-balance condition. This framework allows for the nonperturbative treatment of static magnetic fields using gauge-including atomic orbitals (GIAOs). The GIAO-X2C-CASSCF methodology effectively captures all microstates within the same 2J + 1-degenerate manifold and their splitting in a static magnetic field, which are not accessible through single-reference-based methods. We also present mathematical recursive expressions for evaluating one-electron relativistic integrals by using GIAOs in the presence of a finite magnetic field. Benchmark studies include oxygen and nitrogen K-edge X-ray magnetic circular dichroism spectroscopy (XMCD) for closed-shell organic compounds, as well as L-edge XMCD spectroscopy for the high-spin open-shell transition metal ion Mn2+ and the tetrahedral Mn(II)O46- complex.

Optical and surface properties of Schiff base ligands and Cu(II) and Co(II) complexes

Objectives. To study the transition of electrons in 1,2-phenyl(4’-carboxy)benzylidene Schiff base ligand and transition metal ions, optical properties, as well as the surface chemistry of supported transition metals using diffuse reflectance spectroscopy (DRS); to study the roughness and morphology of the Schiff base ligand and its complexes using atomic force microscopy (AFM).Methods. DRS, AFM, and Fourier-transform infrared spectroscopy instruments were used to identify electron transitions, optical properties, and surface morphology in Schiff base ligands and their complexes.Results. The DRS revealed the d–d transitions and charge transfer shifts of all compounds, and helped identify the structure of the ligand. One of the optical properties studied was the energy gap calculation of the ligand and its complexes. The copper complex exhibited more semiconducting behavior with surface morphology properties such as surface roughness parameters lower than those of the ligand and the cobalt complex. This can be attributed to the smaller size of the copper atom, as well as lower electron transitions compared to the cobalt complex and the square planar bonding shape.Conclusions. In Schiff base ligands, the reflectance spectrum bands reveal three electron transitions: n→π*, π→π*, and σ→σ* transitions. In cobalt complexes, four transitions are indicated: 4A2(F)→4T1(F), 4A2(F)→4T1(P), charge transfer bands, and tetrahedral geometry. Copper complexes exhibit three transitions: 2B1g→2A1g, 2B1g→2Eg, and charge transfer bands, with a square planar geometry for their structure. The energy gap calculations were 2.42, 2.29, and 2.30 eV, respectively. In the case of the SH ligands, copper complexes, and cobalt complexes, all compounds exhibited semiconductor properties. However, the complexes displayed increased conductivity due to the influence of the metal and coordination structure.

Engineering Electrolytes with Transition Metal Ions for the Rapid Sulfur Redox and In Situ Solidification of Polysulfides in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have been pursued due to their high theoretical energy density and superb cost-effectiveness. However, the dissolution-conversion mechanism of sulfur inevitably leads to shuttle effects and interface passivation issues, which impede Li-S battery practical application. Herein, the approach of adopting transition metal salts (CoI2) to engineering the electrolyte is proposed. Different from anchored transition metal catalysts in the cathode, soluble cobalt ions can chemically reduce and solidify polysulfides, alleviating the dependence of sulfur conversion on the conductive interface while suppressing the shuttle effect. Importantly, all elements in CoI2 are in the lowest valence state and solid complexes are formed after the redox reaction, which prevents the migration of high valent Co3+ to the anode, thus overcoming the poor compatibility between redox mediator and Li anode. Notably, I3- has the function of eliminating dead sulfur and dead lithium, which we apply to Li-S batteries. After activating I3- at a certain frequency, Li-S batteries indeed achieve a longer and more stable cycle life. By combining the regulatory behavior of anions and cations, the electrolyte is engineered for Li-S batteries with high capacity, long lifespan, and excellent rate performance.

A Dual Effect Additive Modified Electrolyte Strategy to Improve the Electrochemical Performance of Zinc-Based Prussian Blue Analogs Energy Storage Device.

Prussian blue analogs (PBA) exhibit excellent potential for energy storage due to their unique three-dimensional open framework and abundant redox active sites. However, the dissolution of transition metal ions in water can compromise the structural integrity of PBAs, leading to significant issues such as low cycle life and capacity decay. To address these challenges, we proposed a dual-effect additive-modified electrolyte method to alleviate such issues, introducing sodium ferrocyanide (Na4Fe(CN)6) into aqueous alkaline electrolytes. It could not only capture Zn2+ dissolved on the surface of Na1.86Zn1.46[Fe(CN)6]0.87 (ZnHCF) electrode material during the cycling process but also conduct redox reactions on the electrode surface to provide additional capacitance. Through experiments and molecular simulation calculations, it showed that Na4Fe(CN)6 can restrict the movement of Zn dissolution into the electrolyte on the electrode surface. Based on this, an asymmetric supercapacitor based on ZnHCF//activated carbon was assembled with a modified electrolyte. The assembled supercapacitor displayed a specific capacitance of 1,329.65 mF cm-2, a power density of 2,900 mW cm-2, and an energy density of 388.28 mW h cm-2. This study provides a new idea for the design and construction of stable and efficient PBA energy storage materials by inhibiting the leaching of transition metals in PBA.

Synthesis of Yellow-Emitting Fluorescent Aniline-Doped Ellagic Acid via C-N Coupling Reaction and Its Application in the Selective Detection of Metal Ions

Ellagic acid (EA), a natural polyphenol, features a highly organized planar structure with an extensive sp2 carbon-conjugated area, making it favorable for light energy absorption and fluorescent emission. However, this planar structure can easily aggregate through π-π stacking, leading to aggregation-caused quenching of fluorescence. In this research, aniline-doped ellagic acid (EAAn2) was successfully synthesized via a C-N coupling reaction to address this issue. The fluorescence properties of EAAn2 in various organic solvents were thoroughly investigated. Compared to EA, EAAn2 exhibited a red shift in fluorescence emission, primarily revealing yellow fluorescence instead of the green fluorescence of EA. Moreover, the fluorescence intensity and the concentration at which aggregation-caused quenching occurs for EAAn2 were substantially improved due to the two grafted aniline molecules.EAAn2 was utilized as a molecular fluorescent probe in DMSO to detect three kinds of metal ions: alkali and alkaline-earth metal ions, transition metal ions, and post-transition metal ions, using EA as a control. It was found that the combination of EAAn2 with these metal ions exhibited stronger fluorescence intensity than EA and effectively resisted the blue shift in fluorescence emission due to aniline doping. Based on these results, Mg2⁺ ions could be clearly distinguished from other alkali and alkaline-earth metal ions by differences in their fluorescence emission, as could Cr2⁺ ions among transition metals. This research effectively enhances the fluorescence properties of EA through C-N coupling and demonstrates its greater potential in the detection of metal ions, providing fundamental and valuable information for future fluorescent applications.

The role of multivalent cations in determining the cross-linking affinity of alginate hydrogels: A combined experimental and modeling study

This study explores the development of a comprehensive mathematical model to predict the cross-link density of alginate hydrogels using varying concentrations of divalent and trivalent ions. By systematically investigating the effects of Ca²⁺, Ba²⁺, Cu²⁺, Sr²⁺, Mg²⁺, Fe3⁺ and Al³⁺, the research describes the relationship between ion concentration and cross-link density. Experimental data reveals that the type and concentration of these ions critically influence the mechanical properties of the resulting hydrogels, with trivalent ions such as Fe³⁺ forming stronger, triple cross-links that significantly enhance the hydrogel's mechanical strength. Among the divalent ions, the trend in binding affinity is as follows: Ba²⁺ with the highest affinity followed by Sr²⁺, Ca²⁺ and Cu²⁺, while Mg²⁺ stands out with the lowest affinity, significantly differing from the others. The deviation of Cu²⁺ (transition metal ion) from the expected trend in ion interactions suggests that coordination chemistry, along with ionic radius, valence, and cation coordination abilities, plays a significant role in determining interaction strength with alginate. The proposed model, enhanced with fitting parameters k1 and k2 to account for ion-specific effects, leverages the unique binding affinities and coordination chemistry of each ion to tailor alginate hydrogels for specific applications. The parameter k1 reflects the affinity of the ions for the alginate chains, while k2 captures the coordination abilities and cross-linking efficiency. This work not only advances the understanding of ion-mediated cross-linking in alginate systems but also offers a valuable tool for the design and optimization of hydrogels with precise mechanical properties governed by various applications.

Retraction notice to “The structural, optical, magnetic and photocatalytic properties of transition metal ions doped TiO2 nanoparticles” [J. Alloy. Compd. 581 (2013) 71–78

Retraction notice to “The structural, optical, magnetic and photocatalytic properties of transition metal ions doped TiO2 nanoparticles” [J. Alloy. Compd. 581 (2013) 71–78

Efficient leaching of valuable metals from spent lithium-ion batteries using green deep eutectic solvents: Process optimization, mechanistic analysis, and environmental impact assessment

The accumulation of over 11 million tons of spent lithium-ion batteries (LIBs) by 2030 highlights a critical environmental challenge posed by their large-scale retirement. The efficient recycling valuable metals from spent LIBs can both reduces environmental impact and mitigates the pressing issue of metal resource scarcity. In this context, deep eutectic solvents (DESs) have become a promising option as an eco-friendly solvent, exhibiting great potential for recycling spent LIBs. Therefore, this work proposed an innovative green DES system consisting of choline chloride (ChCl), DL-malic acid (MAL), and glycerol for the efficient leaching of valuable metals from spent LIBs. Comprehensive experiments were conducted to determine the optimum leaching conditions (130 °C, 60 g/L, MChCl:MAL:Glycerol of 1:1:3, 3 h), achieving high leaching efficiencies of 94.6% for Ni, 96.8% for Co, 93.8% for Mn, and 96.4% for Li. Through characterization techniques, kinetics studies, and density functional theory (DFT) calculations, the leaching process was predominantly governed by surface chemical reaction (1-(1-x)1/3 = kt) within the shrinking core model, exhibited activation energies of 49.89 kJ/mol, 47.66 kJ/mol, 50.51 kJ/mol, and 22.24 kJ/mol for Ni, Co, Mn, and Li, respectively. The propensity for DES to leach metal ions followed the order: Li > Co > Ni > Mn, determined by binding energy and energy gaps. Cl− and −COOH within the DES were capable of forming stable complexes with reduced transition metal ions, revealing an efficient coordination leaching mechanism. Additionally, a life cycle assessment (LCA) was conducted on the environmental impacts of the DES leaching process, confirming it as an effective and environmentally friendly method for recycling spent LIBs. This work avoided the employment of corrosive acids and alleviated the generally harsh conditions associated with DESs leaching, providing a viable solution for recovering spent LIBs.

Research on the application of catalytic complex between transitional metal ion cobalt (II) and citric acid to treat organic pollutants contained in textile wastewater

Research on the application of catalytic complex between transitional metal ion cobalt (II) and citric acid to treat organic pollutants contained in textile wastewater

Heterostructure Engineering of Biphase‐Coupled Ternary Transition Metal Phosphoselenide by Topological Transformation Enabling High Performance for Supercapacitors

AbstractThe exploration of promising electrode materials with structural stability and rapid interfacial reaction kinetics is highly desirable for supercapacitors toward large‐scale applications. Herein, the synthesis of biphase‐coupled CoPSe/NiP0.24Se1.76 with multiple in‐plane heterointerfaces using the in situ topological transformation approach is presented. As a novel ternary metal phosphoselenide (TMPSe) for supercapacitor cathode that is fabricated by synchronous phosphoselenization strategy, it realizes a superior lifespan with cycling compared to conventional transition metal selenides. The depleted anti‐bonding eg* orbitals of transition metal ions (Co/Ni) in the CoPSe/NiP0.24Se1.76, as proved by preliminary theoretical calculations, strengthens the chemical bonding between Co/Ni and coordinating atoms, thereby enhancing the chemical stability. Simultaneously, the CoPSe/NiP0.24Se1.76 in‐plane multi‐heterostructures can not only alleviate the volume change during the charge–discharge process but also expose more active sites, promoting the adsorption of OH− ions, which is conducive to the rapid redox reaction kinetics of the CoPSe/NiP0.24Se1.76, and consequently, it delivers a remarkable reversible capacity and excellent long‐term cycle stability with 97.7% initial capacitance retention over 16 000 cycles. Moreover, the asymmetric supercapacitors with this cathode demonstrate outstanding rate capability and high energy density. This strategy of constructing biphase‐coupled CoPSe/NiP0.24Se1.76 by topological transformation is of great potential application for the high‐performance electrode material.

Accelerating Small Electron Polaron Dissociation and Hole Transfer at Solid-Liquid Interface for Enhanced Heterogeneous Photoreaction.

In a photocatalysis process, quick charge recombination induced by small electron polarons in a photocatalyst and sluggish kinetics of hole transfer at the solid-liquid interface have greatly limited photocatalytic efficiency. Herein, we demonstrate hydrated transition metal ions as mediators that can simultaneously accelerate small electron polaron dissociation (via metal ion reduction) and hole transfer (through high-valence metal production) at the solid-liquid interface for improved photocatalytic pollutant degradation. Fe3+, by virtue of its excellent redox ability as a homogeneous mediator, enables the BiVO4 photocatalyst to achieve drastically increased photocatalytic degradation performance, up to 684 times that without Fe3+. The enhanced performance results from Fe(IV) species production (via Fe3+ oxidation) induced by dissociation of small electron polarons (via Fe3+ reduction), featuring an extremely low kinetic barrier (5.4 kJ mol-1) for oxygen atom transfer thanks to the donor-acceptor orbital interaction between Fe(IV) and organic pollutants. This work constructs a high-efficiency artificial photosynthetic system through synergistically eliminating electron localization and breaking hole transfer limitation at the solid-liquid interface for constructing high-efficiency artificial photosynthetic systems.

Elevating Nonlinear Optical Response Through D-Electron Modulation in Metal-Organic Frameworks.

Electronic structure and excited state behavior is of pronounced influence on regulation of nonlinear optical (NLO) response. Herein, a serials of transition metal ions bearing different d-electron numbers were in situ coordinated within porphyrinic metal-organic frameworks (MOFs), creating NLO-responsive M-metal (metal=Fe, Co, Ni, Cu, and Zn) frameworks. It demonstrated that the NLO properties can be optimized with the increased occupancy of the d-shell, which enhances the degree of delocalization. Specifically, the full-filled (d10) electron configuration of Zn2+ stabilizes the electronic structure, combination with π-π* local excitation character of M-Zn, promoting charge transfer process and resulting in outstanding NLO properties. Moreover, parameters related to the nonlinear process (β, n2, Imχ(3), Reχ(3) and χ(3)) of M-Zn are calculated to be higher than those of other materials, consistent with theoretical calculations. This work paves the way for NLO modulation based on electronic analysis and provides a promising approach for constructing high-performance NLO materials.

Nanoflower-like NiCoFe layered hydroxide by in-situ electrochemical corrosion as highly efficient electrocatalyst for water oxidation

Layered double hydroxides have been widely applied for oxygen evolution reaction (OER) in the alkaline water electrolysis. However, the issues of poor connection between the catalyst and nickel foam and the specific mechanisms for active sites has not been fully documented. In this study, the in-situ nickel foam etching in a mixed solution of ferric chloride and cobalt nitrate at low temperatures was adopted for NiCoFe layered ternary hydroxides (NiCoFe LTHs) synthesis with a better tight integration. Physicochemical characterization indicated that the NiCoFe LTHs could grow directly through corroding nickel foam with a nano-flower-like morphology and structures. That is favorable for electron transfer from the catalytic layer to the conductive substrate. With the transition metal ions interaction and the tight integration construction, NiCo1Fe4-LTH-T60/NF presented an enhanced electrolysis performance with the overpotential of 234 mV (1.464 V vs. RHE) at current density of 100 mA cm−2 in 1 M KOH electrolyte. The Tafel slope for NiCo1Fe4-LTH-T60/NF electrode was 36.19 mV dec−1 for an enhanced OER kinetics. Besides, it demonstrated faster interfacial charge transfer process, better intrinsic electrochemical activity and stability in large current stability testing. It was revealed that the synergistic effect of the transition metal ions interaction enhancement and the mechanism of oxygen evolution elementary reaction for NiCo1Fe4-LTH-T60/NF during the water electrolysis by the electrochemical and theoretical calculation. This work provides theoretical basis and experimental support for the design and synthesis of future OER catalyst and substrate, which is significant for hydrogen and oxygen generation from water electrolysis.

Fabrication of a novel mixed-valent copper-based coordination polymer as a fluorescent sensor for selective and efficient detection of multiple analytes

A novel three-dimensional fluorescent mixed-valent copper-based coordination polymer (CP), namely {[CuICuII4(triazol)6(bpta)2]Cl}n (Cu-CP), was synthesized hydrothermally in the presence of Cu(II) ion, 2,4,6-tri(1H-1,2,4-triazol-1-yl)-1,3,5-triazine (TTT), and 2,2′,4,4′-biphenyltetracarboxylic acid (H4bpta). The structure of the Cu-CP was studied using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD). Interestingly, the crystallographic data revealed that a part of Cu(II) ions were reduced in situ to Cu(I) ions as well as the nitrogen-containing ligand TTT was converted to triazol, which possessed excellent fluorescence characteristics as a transition metal ion with a d10 electronic configuration, prompting further investigation into the fluorescence sensing properties of Cu-CP. The results confirmed that Cu-CP exhibited excellent fluorescence performance which an outstanding candidate as a fluorescence sensor for Fe3+, Cr2O72−, CrO42−, MnO4− and nitrobenzene (NB), with a low limit of detection. For ethylene glycol (EG) detection, Cu-CP showed high-efficiency fluorescence enhancement across a range of temperatures. The underlying mechanism of fluorescence enhancement was investigated through comprehensive experimental studies.

Bimetallic Uranium Complexes with 2,6-Dipicolinoylbis(N,N-Dialkylthioureas).

2,6-Dipicolinoylbis(N,N-dialkylthioureas), H2LR, readily react with uranyl salts under formation of monomeric or dimeric complexes of the compositions [UO2(LR)(solv)] (solv = donor solvents such as H2O, MeOH or DMF) or [{UO2(LR)(µ-OMe)}2]2- (1). In such complexes, the uranyl ions are exclusively coordinated by the "hard" O,N,O or N,N,N donor atom sets of the central ligand unit and the lateral sulfur donor atoms do not participate in the coordination. Different conformations have been found for the dimeric anions. The bridging methanolato ligands and the four uncoordinated sulfur atoms can adopt different orientations with respect to the equatorial coordination spheres of the uranyl units. The presence of non-coordinated sulfur atoms offers the opportunity for the coordination of additional, preferably "soft" metal ions. Thus, reactions with [AuCl(PPh3)], lead acetate or acetates of transition metal ions such as Ni2+, Co2+, Fe2+, Mn2+, Zn2+, or Cd2+, were considered for the syntheses of bimetallic complexes. Various oligometallic complexes with uranyl units were prepared: [{UO2(LR)(μ-OMe)(Au(PPh3)}2] (2), [(UO2)3Pb2(LR)4(MeOH)2(μ-OMe)2] (3), [M{UO2(LR)(OAc)}2] (M= Zn, Ni, Co, Fe, Mn or Cd) (R = Et: 5, RR = morph: 6), or [(UO2)(NiI)2(LR)2] (7). The products were extensively studied spectroscopically and by X-ray diffraction.