Ethylenediamine Ligands Research Articles

Chelating ligand-bridged IO-Gd nanoparticles with enhanced contrast performance for dual-mode MRI

Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that has been widely applied in the clinical diagnosis of diseases across various fields. Currently, there is a dearth of high-performance dual-mode contrast agents that provide precise diagnostic information for complex diseases. In this study, iron oxide-gadolinium nanoparticles (IO-Gd NPs) bridged by hydrophilic ligand ethylenediamine tetramethylenephosphonic acid (EDTMP) are designed inspired by Solomon-Bloembergen–Morgan (SBM) theory, where T1 and T2 relaxivity increase with a reduction in Gd content. In particular, the NPs with minimum Gd content exhibit excellent dual-mode contrast performance (r1 = 94.42 mM−1 s−1, r2 = 343.62 mM−1 s−1). The underlying mechanism is that the bridged EDTMP coordinate limits Gd tumbling and forces Gd3+ to expose itself to the surface of the NPs. This provides more opportunities for water molecules to coordinate with Gd3+ and significantly enhances proton relaxivity. Moreover, the hydrophilicity of the ligand enhances the water dispersion stability of the NPs and increases the exchange rate of water protons near the NPs, further enhancing the dual-mode contrast effect. Finally, the biocompatibility and in vitro/vivo imaging performances of the IO@EDTMP-Gd NPs are systematically evaluated, and the results demonstrate their potential as dual-mode contrast agents. This study provides a new strategy for developing dual-mode MRI contrast agents that can further improve the accuracy of MRI in the diagnosis of complex diseases.

Isolation of Sillica from Pantai Cermin Sand and Modification with Sodium Lauryl Sulfate and Ligan Ethylendyamine Through Coating Method as Absorption of Pb Metal

Research on the formation of synthesis and modification coating of silica and obtained silica with a quartz structure used to absorb lead metal ions. This isolation was performed by extracting silica from sand with the co-precipitation method using NaOH 7M and then adding HCl 2M. The resulting silica was coated with sodium lauryl sulfate and ethylenediamine to increase adsorption. The FT-IR spectrum on silica shows the presence of Si-O-Si, Si-O-, Si-OH, S–O, SO3, CH2, and NH—Sillica coating, which sodium lauryl sulfate and ethylenediamine ligands were carried out by coating method at pH 2. The results obtained before and after coating on silica were characterized by FT-IR, XRD, and SEM EDX analysis. The FT-IR spectrum on sillica showed the presence of Si-O-Si, Si-O, and Si-OH functional groups. After the coating, there was a change in the spectrum, indicating new functional groups in the S-O, SO3, CH2, and NH spectra. Characterization using XRD shows the diffraction peaks were of 2𝛳 27,6297°, which indicates the amorph. After coating, the diffraction peaks appeared at an angle of 2𝛳 in the area of 19.62 °, 20.47°, 21.04 °, 25.56 °, 26.50 °, and 29.73 ° with a high enough intensity indicating increased crystallinity. The morphology, composition, and size of the silica produced before and after coating were observed by SEM-EDX. Where there is a change in the size before and after a modification, that is 100,788 nm to 85,3773 nm. Silica before and after coating is used as an adsorbent to reduce levels of heavy metal lead (Pb). This analysis showed that the adsorption of Pb²⁺ with silica was 4,5162 ppm, while the adsorption of Pb²⁺ after coating was 1,1146 ppm.

Investigating the Effect of Tuning the Metal Center in Complexes for Nonlinear Optical Application

In this study, the new transition metal complexes, ML with M = Zn (II), Ni (II), and Pd (II) based on the N,N'-Bis[O-(diphenylphosphino)benzylidene)ethylenediamine ligand were successfully synthesized with a percentage yield of between 33 – 68%. As a result of fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy (UV-vis), and 1H nuclear magnetic resonance (proton NMR) was used to design and completely describe the metal complexes properties. Moreover, for computational study, the Gaussian16 software installed in the high-performance computer (HPC) is used for NLO calculation. The method used to perform this study is Density Functional Theory (DFT) method. 6-31G(d,p) basis set is used with LANL2DZ for zinc, nickel, and palladium along with the keyword ‘GEN’. The molecular structure has been optimized and checked both bond length and bond angle before starting to run the calculation. Thus, NLO calculation had been performed. The dipole moment and the HOMO-LUMO energy gap were employed to verify the first hyperpolarizability, βtot, which can be utilized as an indication of second nonlinear optical characteristics. Transition metal-based complexes produce impressive results because they provide additional flexibility by offering charge transfer (CT) transitions between the metal and the ligands, resulting in a higher NLO response. Due to the charge transfer excitations, it was discovered that the nickel complex with 2.87 D had the largest NLO response (117215.66 x 10-30 esu), particularly in comparison with the zinc complex (2329.72 x 10-30 esu) and palladium complex (191.07 x 10-30 esu) with 6.52 D and 4.04 D values, respectively.

Green and Cost-Effective Separation of Cadmium from Base Metals in Chloride Medium with Halide-Loaded Anion Exchanger

A novel strategy for the separation of cadmium from base metals in chloride medium by anion exchange based on the formation of cadmium halo-complexes is presented in this article. Instead of using excess Br− or I− in the feed solution, the anion exchange resin or fibre was first preloaded with Br− or I− for Cd2+ adsorption from Cl− solution. Thus, the consumption of iodide or bromide was minimized while promising high adsorption stability of Cd2+. The adsorption thermodynamics and kinetics of Cd2+ were studied. The adsorption thermodynamics results were processed with Langmuir and Freundlich models and adsorption kinetics results were treated with Pseudo first order model, Pseudo second order model and intraparticle diffusion model. The adsorption mechanism was studied with the aid of FTIR and elemental analysis. Three strategies were applied for the stripping of Cd2+, including the use of water for disequilibrating its halo-complex formation, the formation of positively charged species with ammonia, and the formation of positively charged chelate with multidentate ligand ethylenediamine. On the bases of these results, separation performance was investigated with strongly basic anion exchange resin and fibre, and it was shown that Cd2+ can be efficiently separated from base metals in a wide range of acidity, and that pure Cd2+ solution can be obtained, thus providing a robust, environmentally friendly, and economic technology for its separation.

Size-Controlled Palladium Nanoparticles Encapsulated in Silicalite-1 for Methane Catalytic Combustion

A series of Pd catalysts with different nanoparticle sizes encapsulated in Silicalite-1 (S-1) zeolite were synthesized using the one-step hydrothermal method to investigate the size dependence on methane catalytic oxidation. The obtained Pd nanoparticle (NP) sizes ranging from 1.8 to 3.2 nm were modulated by changing the addition of the ethylenediamine (EN) ligand during the synthesis process, and Pd/S-1-in-6EN (2.1 nm, the molar composition of 1 Pd:6 EN) displayed the remarkable catalytic performance. Meanwhile, long-term stability tests indicate the outstanding water resistance of Pd/S-1-in-6EN with a smaller particle size. According to the results of in situ CO-DRIFTS, a volcano-shaped curve between the fraction of the step site by size control of Pd nanoparticles and the catalytic performance was presented, and Pd/S-1-in-6EN possessed the optimum one. These allow the further study of the particle size effect on zeolite-confined noble metal catalysts for methane combustion.

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1-15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210-596 m2·g-1, an apparent density of 0.403-0.740 cm3·g-1 and a porosity of 60-78%. The actual cobalt content in the aerogels was 0.01-1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.

Sintering-resistant and highly active Au/SBA-15 catalyst for carbon monoxide oxidation

The low thermal stability of gold-based catalysts is a significant obstacle to their practical application, especially under demanding conditions, such as those prevailing in automotive exhaust gas converters. In this work, we demonstrate that it is possible to strongly anchor 2–3 nm size gold nanoparticles inside the pores of SBA-15 mesoporous silica. The Au/SBA-15 catalyst showed high thermal stability, even at a temperature of 700–800 °C. The gold was evenly distributed inside the SBA-15 mesopores using the adsorption of the [Au(en)2]Cl3 complex (en = ethylenediamine) in an alkaline environment. Due to the very small size of gold nanoparticles, the obtained catalyst was highly active in low-temperature CO oxidation. The high resistance of Au particles to sintering can be explained by the confinement effect and the strong metal-support interaction, induced during the catalyst precursor decomposition under an oxygen-free atmosphere at 400 °C. The carbonaceous layer, formed from ethylenediamine ligands decomposition, plays an essential role in stabilizing gold nanoparticles inside the SBA-15 pores. We believe that our findings may contribute to solving the problem of carbon monoxide emission during engine start-up.

Acetone Factor in the Design of Cu4-, Cu6-, and Cu9-Based Cage Coppersilsesquioxanes: Synthesis, Structural Features, and Catalytic Functionalization of Alkanes

The present study describes a new feature in the self-assembly of cagelike copperphenylsilsesquioxanes: the strong influence of acetone solvates on cage structure formation. By this simple approach, a series of novel tetra-, hexa-, or nonacoppersilsesquioxanes were isolated and characterized. In addition, several new complexes of Cu4 or Cu6 nuclearity bearing additional nitrogen-based ligands (ethylenediamine, 2,2'-bipyridine, phenanthroline, bathophenanthroline, or neocuproine) were produced. Single-crystal X-ray diffraction studies established molecular architectures of all of the synthesized products. Several coppersilsesquioxanes represent a novel feature of cagelike metallasilsesquioxane (CLMS) in terms of molecular topology. A Cu4-silsesquioxane complex with ethylenediamine (En) ligands was isolated via the unprecedented self-assembly of a partly condensed framework of silsesquioxane ligands, followed by the formation of a sandwich-like cage. Two prismatic Cu6 complexes represent the different conformers─regular and elliptical hexagonal prisms, "cylinders", determined by the different orientations of the coordinated acetone ligands ("shape-switch effect"). A heterometallic Cu4Na4-sandwich-like derivative represents the first example of a metallasilsesquioxane complex with diacetone alcohol ligands formed in situ due to acetone condensation reaction. As a selected example, the compound [(Ph6Si6O11)2Cu4En2]·(acetone)2 was explored in homogeneous oxidation catalysis. It catalyzes the oxidation of alkanes to alkyl hydroperoxides with hydrogen peroxide and the oxidation of alcohols to ketones with tert-butyl hydroperoxide. Radical species take part in the oxidation of alkanes. Besides, [(Ph6Si6O11)2Cu4En2]·(acetone)2 catalyzes the mild oxidative functionalization of gaseous alkanes (ethane, propane, n-butane, and i-butane). Two different model reactions were investigated: (1) the oxidation of gaseous alkanes with hydrogen peroxide to give a mixture of oxygenates (alcohols, ketones, or aldehydes) and (2) the carboxylation of Cn gaseous alkanes with carbon monoxide, water, and potassium peroxodisulfate to give Cn+1 carboxylic acids (main products), along with the corresponding Cn oxygenates. For these reactions, the effects of acid promoter, reaction time, and substrate scope were explored. As expected for free-radical-type reactions, the alkane reactivity follows the trend C2H6 < C3H8 < n-C4H10 < i-C4H10. The highest total product yields were observed in the carboxylation of i-butane (up to 61% based on i-C4H10). The product yields and catalyst turnover numbers (TONs) are remarkable, given an inertness of gaseous alkanes and very mild reaction conditions applied (low pressures, 50-60 °C temperatures).

Tuning of Cr-Cr Magnetic Exchange through Chalcogenide Linkers in Cr2 Molecular Dimers.

A set of three Cr-dimer compounds, Cr2Q2(en)4X2 (Q: S, Se; X: Br, Cl; en: ethylenediamine), with monoatomic chalcogenide bridges have been synthesized via a single-step solvothermal route. Chalcogenide linkers mediate magnetic exchange between Cr3+ centers, while bidentate ethylenediamine ligands complete the distorted octahedral coordination of Cr centers. Unlike the compounds previously reported, none of the chalcogenide atoms are connected to extra ligands. Magnetic susceptibility studies indicate antiferromagnetic coupling between Cr3+ centers, which are moderate in Cr2Se2(en)4X2 and stronger in Cr2S2(en)4Cl2. Fitting the magnetic data requires a biquadratic exchange term. High-frequency EPR spectra showing characteristic signals due to coupled S = 1 spin states could be interpreted in terms of the "giant spin" Hamiltonian. A fourth compound, Cr2Se8(en)4, has a single diatomic Se bridge connecting the two Cr3+ centers and shows weak ferromagnetic exchange interactions. This work demonstrates the tunability in strength and type of exchange interactions between metal centers by manipulating the interatomic distances and number of bridging chalcogenide linkers.

Solvothermal Synthesis of [Cr7 S8 (en)8 Cl2 ]Cl3 ⋅ 2H2 O with Magnetically Frustrated [Cr7 S8 ]5+ Double-Cubes.

A novel transition metal chalcohalide [Cr7S8(en)8Cl2]Cl3 ⋅ 2H2O, with [Cr7S8]5+ dicubane cationic clusters, has been synthesized by a low temperature solvothermal method, using dimethyl sulfoxide (DMSO) and ethylenediamine (en) solvents. Ethylenediamine ligand exhibits bi‐ and monodentate coordination modes; in the latter case ethylenediamine coordinates to Cr atoms of adjacent clusters, giving rise to a 2D polymeric structure. Although magnetic susceptibility shows no magnetic ordering down to 1.8 K, a highly negative Weiss constant, θ=−224(2) K, obtained from Curie‐Weiss fit of inverse susceptibility, suggests strong antiferromagnetic (AFM) interactions between S=3/2 Cr(III) centers. Due to the complexity of the system with (2S+1)7=16384 microstates from seven Cr3+ centers, a simplified model with only two exchange constants was used for simulations. Density‐functional theory (DFT) calculations yielded the two exchange constants to be J 1=−21.4 cm−1 and J 2=−30.2 cm−1, confirming competing AFM coupling between the shared Cr3+ center and the peripheral Cr3+ ions of the dicubane cluster. The best simulation of the experimental data was obtained with J 1=−20.0 cm−1 and J 2=−21.0 cm−1, in agreement with the slightly stronger AFM exchange within the triangles of the peripheral Cr3+ ions as compared to the AFM exchange between the central and peripheral Cr3+ ions. This compound is proposed as a synthon towards magnetically frustrated systems assembled by linking dicubane transition metal‐chalcogenide clusters into polymeric networks.

Synthesis and structure determination of racemic (Δ/Λ)-tris-(ethyl-enedi-amine)-cobalt(III) trichloride hemi(hexa-aqua-sodium chloride).

The synthesis and crystal structure of the title racemic compound, [Co(C2H8N2)3]Cl3.{[Na(H2O)6]Cl}0.5, are reported. The trivalent cobalt atom, which resides on a crystallographic threefold axis, is chelated by a single ethyl-ene di-amine (en) ligand and yields the tris-chelate [Co(en)3]3+ cation with distorted octa-hedral geometry after the application of crystal symmetry. The sodium cation (site symmetry ), has a single water mol-ecule bound to it in the asymmetric unit and yields a distorted, octa-hedrally coordinated hydrated [Na(H2O)6]+ cation after the application of symmetry. One of the chloride ions lies on a general position and the other has site symmetry. An extensive array of C-H⋯O, N-H⋯Cl and O-H⋯Cl hydrogen bonds exists between the ethyl-ene di-amine ligands, the water mol-ecules of hydration, and the anions present, thereby furnishing solid-state stability.

Amino-grafted Cu and Sc Metal-Organic Frameworks involved in the green synthesis of 2-amino-4H-chromenes. Mechanistic understanding

In this work, we report for the first time a new methodology for the eco-synthesis of 2-amino-4 H -chromenes 1 , from salycilaldehydes and cyano compounds, under solvent-free and mild conditions, using amino-grafted MOFs as catalysts. The selected MOFs − commercial CuBTC and MIL-100(Sc) previously synthetized in our laboratories − can be easily functionalyzed with amines of different nature showing notable differences in their composition and textural properties. The total or partial functionalization of the metal centers in starting MOFs is strongly depending on the functionalization method used. Our results indicate that the catalytic performance is mainly conditioned by the type and concentration of basic sites, porosity of the samples barely showing any influence. The methodology herein reported could be considered as an environmental friendly alternative to the selective chromene synthesis, which allows to achieve high yields in relatively short reaction times (up to 90% over 1 h), using notably small amounts of easily prepared catalysts. Furthermore, our experiments in combination with theoretical calculations strongly suggest that free-amine groups in ethylenediamine (EN) functionalized catalysts can act either as individual catalytic sites, as for EN-M/CuBTC sample, in which all metal centers are functionalized with EN ligands and shows the highest concentration of basic catalytic sites, or acting in cooperation with the closest metal centers in samples partially functionalized, as in the case of EN/CuBTC sample. • Amino-grafted MOFs are able to efficiently catalyze the chromene synthesis • Functionalization of selected MOF is strongly depending on the method used • Amine functions in MOF can be act as individual catalytic sites • A cooperation of amine groups with the nearest metal CUS probably takes place in the reaction

Thermal properties of the hybrid compound [Cu(en)2(VO3)2]•3H2O — phase analysis upon heating and cooling. Crystal structure characterization of its two polymorphic modifications

The inorganic-organic hybrid compound [Cu(en)2(VO3)2]•3H2O (1) was prepared by crystallization at room temperature from the CuSO4•5H2O – KVO3 – ethylenediamine – H2O system. Upon cooling 1, phase transition occurred at 176 K. Single-crystal diffraction analysis of the high- temperature and low-temperature phases has shown both phases to be polymeric, incorporating metavanadate chains (VO3)nn– coordinated via oxygen atoms to copper(II) atoms. The four remaining positions of the copper atoms with octahedral environment are taken by nitrogen atoms of two ethylenediamine ligands. The low-temperature phase exhibits displacive modulation in its structure. The band gap of the high-temperature phase is 2.95 eV. The compound is paramagnetic (1.79 µB) and exhibits no distinct magnetic interactions. A detailed phase analysis upon heating of 1 to 600 °C revealed the final products of the thermal decomposition to be monoclinic Cu(VO3)2, Cu2V2O7 as ziessite and V2O5. After cooling to room temperature, monoclinic Cu(VO3)2 transformed to its triclinic polymorph, while ziessite became transformed to blossite.

Design, synthesis, and catalytic performance of modified graphene oxide based on a cobalt complex as a heterogenous catalyst for the preparation of aminonaphthoquinone derivatives.

We are reporting a functionalized graphene oxide catalyst developed by modifying graphene oxide surface using the covalent attachment of an amino-functionalized SiO2 sphere/cobalt complex. Silica network has special characteristics including mechanical strength, high thermal and chemical stability with good dispersion in solvents. The silica/graphene oxide mixture provides improved properties and extends the scope of application. Graphene oxide was functionalized by spherical silica with the help of hybrid silane-containing nitrogen to coordinate with Co(ii) for increasing the catalytic activity. The catalyst was characterized by Fourier Transform Infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Raman spectroscopy, and Thermal Gravimetric (TGA) analyses. The catalyst showed high catalytic activity for multi-component reactions in the synthesis of aminonaphthoquinones in ethanol solvent. The catalyst's ability to improve the yield (96–98%), reduce the reaction time (5–8 min), and recycling ability are important benefits for the catalyst.

From groove binding to intercalation: unravelling the weak interactions and other factors modulating the modes of interaction between methylated phenanthroline-based drugs and duplex DNA.

Several antitumor drugs base their cytotoxicity on their capacity to intercalate between base pairs of DNA. Nevertheless, it has been established that the mechanism of intercalation of drugs in DNA starts with the prior groove binding mode of interaction of the drug with DNA. Sometimes, for some kind of flat small molecules, groove binding does not produce any cytotoxic effect and the fast transition of such flat small molecules to the cytotoxic intercalation mode is desirable. This is the case of methylated phenanthroline (phen) derivatives, where, changes in the substitution in the position and number of methyl groups determine their capability as cytotoxic compounds and, therefore, it is a way for the modulation of cytotoxic effects. In this work, we studied this modulation by means of the interaction of the [Pt(en)(phen)]2+ complex and several derivatives by methylation of phen in different number and position and the d(GTCGAC)2 DNA hexamer via groove binding using PM6-DH2 and DFT-D methods. The analysis of the geometries, electronic structure and energetics of the studied systems was compared to experimental works to gain insight into the relation structure-interaction for the studied systems with cytotoxicity. The trends are explained by means of the Non-Covalent Interaction (NCI) index, the Energy Decomposition Analysis (EDA) and solvation contributions. Our results are in agreement with the experiments, in which the methylation of position 4 of phen seems to favour the interaction via groove binding thus making the transition to the intercalation cytotoxic mode difficult. Looking at the NCI results, these interactions come not only from the CH/π and CH/n interactions of the methyl group in position 4 but also from the ethylenediamine (en) ligand, whose orientation in the Pt complex was found in such a way that it produces a high number of weak interactions with DNA, especially with the sugar and phosphate backbone.

Synthesis, characterization and crystal structure determination of aluminum hydride complexes of N, N′- Di(isopropyl)ethylenediamine ligand

Reaction of alane-amine adduct, AlH3·NMe2Et, with N, N´-di(isopropyl)ethylenediamine was conducted for the preparation of amide ligated aluminum hydride complexes via dehydrocoupling pathway. Depending on the proportion of the reagents (1:1 and 3:2) two different products (1) and (2) were isolated. Compounds 1 and 2 were characterized using different spectroscopic techniques along with the determination of solid-state molecular structure via single crystal X-ray diffraction studies. In the crystal lattice of complex 2, molecules are connected via weak Al-H…HC hydrogen bonding supramolecular interactions to form polymeric arrangements of the molecule. Further, a reaction of 2 with two equivalents of 1, 2-diphenylethylene-glycol generated complex 3 that was isolated in trace quantities. Molecular structure of 3 was also determined using single crystal X-ray diffraction study.

Mixed-ligand nickel(ii) and copper(ii) complexes in competitive chelation reactions with polyaminopolyacetate and polyamine ligands

The mixed-ligand and competitive formation of coordination compounds in aqueous solutions of ternary systems containing nickel(ii) or copper(ii) cations, polyaminopolyacetate (nitrilo triacetic, ethylenediaminetetraacetic, or diethylenetriaminepentaacetic acid), and polyamine (ethylenediamine, diethylenetriamine, or triethylenetetramine) ligands was studied by spectrophotometry. The factors were determined which facilitate the formation of mixed-ligand complexes of composition [ML1L2] (M is NiII or CuII, L1 is a polyaminopolyacetate chelating agent, L2 is a polyamine ligand) in aqueous solutions. In these complexes, amines act predominantly as polydentate chelating ligands and the coordination sphere of metal atoms is completed by nitrogen and oxygen atoms of the chelating agents. An increase in the denticity of the polyamine ligand was found to increase the number of ethylenediamine metallocycles and promote partial cleavage of glycinate rings of carboxylate ligands in the coordination polyhedron of the chelate, thereby providing an increase in the stability of the resulting mixed-ligand complex species. In systems containing copper(ii) cations, the ability of polyamine ligands to exhibit a discriminatory effect and block the coordination of the polyaminopolyacetate chelating ligand was shown to vary and depend on the combination of L1 and L2 ligands in the coordination sphere.

Coordination Affinity of Cu(II)-Based Silsesquioxanes toward N,N-Ligands and Associated Skeletal Rearrangements: Cage and Ionic Products Exhibiting a High Catalytic Activity in Oxidation Reactions

An unusual skeletal rearrangement of piperazine into ethylenediamine has been observed for the first time as a result of an attempt to synthesize a piperazine-linked metal-organic framework (MOF) using cage Cu(II),Na-phenylsilsequixane as a potential building block. Instead of the expected "metallasilsesquioxane-based MOF", a Cu6 complex 1 coordinated both by silsesquioxane and ethylenediamine ligands was isolated. An effort to reproduce this result via direct interaction of Cu-phenylsilsequioxane and ethylenediamine surprisingly afforded two other types of complexes, copper-sodium 2 and copper 3 ionic products. Cationic components in both products 2 and 3 are represented by (i) copper and sodium ions (in the case of 2) or (ii) copper ions exclusively (in the case of 3) coordinated by ethylenediamine ligands. Both complexes 2 and 3 include Si6-based condensed silsesquioxane fragments serving as anionic components of the products. Symptomatically, the types of the Si6-frameworks in 2 and 3 are drastically different. More specifically, the Si6 unit in 2 is an unprecedented distorted silsesquioxane skeleton consisting of two condensed tetramembered rings. Structural features of compounds 1-3 were established by single crystal X-ray diffraction. Compound 2 was found to catalyze the oxidation of cyclohexane to cyclohexanol and cyclohexanone with H2O2 (a mixture of these products was obtained after adding PPh3 to the reaction solution) as well as the transformation of cyclohexanol to cyclohexanone under the action of tert-butyl hydroperoxide.

Covalent conductive polymer chain and organic ligand ethylenediamine modified MXene-like-{AlW12O40} compounds for fully symmetric supercapacitors, electrochemical sensors and photocatalysis mechanisms

The covalent conductive polymer chain and organic ligand ethylenediamine modified MXene-like-{AlW12O40} compounds are proposed to facilitate the discovery of promising photo-electrically active materials.

Hierarchical carbon microflowers supported defect-rich Co3S4 nanoparticles: An efficient electrocatalyst for water splitting

Developing highly efficient and cost-effective bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) represents a judicious way to produce massive hydrogen fuel through electrochemical water splitting. Herein, defect-rich Co3S4 particles with a diameter less than 5 nm were in-situ grown on nitrogen-doped hierarchical carbon microflowers (Co3S4@FNC) through a simple hydrothermal method, in which an unconventional vulcanization process with the strongly coordinating ligand ethylenediamine and formaldehyde serving as structure-directive agents is resorted to effectively control the morphology of catalysts. The resultant Co3S4@FNC-Co3 comprises dense Co3S4 nanoparticles supported on ultrathin nitrogen-doped carbon nanosheets with a thickness of ca. 20 nm, as well as abundant defects on Co3S4 nanoparticles and highly porous textures on carbon microflowers. These nanostructure merits lead to efficient catalytic activities, featuring a small overpotential of only 250 mV and 140 mV for OER and HER electrocatalysis at 10 mV cm−2. When Co3S4@FNC-Co3 is utilized as a bifunctional catalyst in an alkaline water electrolyzer, a bias of only 1.580 V is able to complement overall water splitting at 10 mA cm−2. Results in present work may suggest a paradigm in the design and engineering of high-performance electrocatalysts based on nanocomposites of transition metal sulfides and carbons.