Metal-organic Coordination Complexes Research Articles

Retraction Note to: Three New Metal-Organic Coordination Complexes: Crystal Structures and Anticancer Activity in Multiple Myeloma

Retraction Note to: Three New Metal-Organic Coordination Complexes: Crystal Structures and Anticancer Activity in Multiple Myeloma

Thin film composite reverse osmosis membranes with metal-organic coordination complexes stabilized CNTs interlayer for enhanced removal of trace organic contaminants

Reverse osmosis (RO) has been recognized as a reliable technique for wastewater reclamation. To enhance its rejection of trace organic contaminants (TrOCs), a novel strategy was proposed to improve reverse osmosis (RO) membranes by fabricating thin-film nanocomposite membrane (TFNi) with a TA-Fe3+/CNTs interlayer. The TFNi-30 membrane was obtained by optimizing the loading capacity. This optimized membrane gave rise to an enhanced water permeance of 3.2 ± 0.2 L m-2 h-1 bar-1, which was two times higher than that of the control membrane (1.1 ± 0.2 L m-2 h-1 bar-1), while achieving a considerably higher rejection of inorganic salts and trace organic contaminants (TrOCs) thanks to the formation of a denser polyamide rejection layer. In addition, the specific roles of the interlayer structure in determining the separation performance of RO membranes were investigated by tailoring the support-free RO membranes and comparing them with the conventional membranes. This study would provide a peer reference for designing high performance RO membranes for wastewater reclamation via the TFNi strategy.

Origins of Structural Elasticity in Metal-Phenolic Networks Probed by Super-Resolution Microscopy and Multiscale Simulations.

Metal-phenolic networks (MPNs) are amorphous materials that can be used to engineer functional films and particles. A fundamental understanding of the heat-driven structural reorganization of MPNs can offer opportunities to rationally tune their properties (e.g., size, permeability, wettability, hydrophobicity) for applications such as drug delivery, sensing, and tissue engineering. Herein, we use a combination of single-molecule localization microscopy, theoretical electronic structure calculations, and all-atom molecular dynamics simulations to demonstrate that MPN plasticity is governed by both the inherent flexibility of the metal (FeIII)-phenolic coordination center and the conformational elasticity of the phenolic building blocks (tannic acid, TA) that make up the metal-organic coordination complex. Thermal treatment (heating to 150 °C) of the flexible TA/FeIII networks induces a considerable increase in the number of aromatic π-π interactions formed among TA moieties and leads to the formation of hydrophobic domains. In the case of MPN capsules, 15 min of heating induces structural rearrangements that cause the capsules to shrink (from ∼4 to ∼3 μm), resulting in a thicker (3-fold), less porous, and higher protein (e.g., bovine serum albumin) affinity MPN shell. In contrast, when a simple polyphenol such as gallic acid is complexed with FeIII to form MPNs, rigid materials that are insensitive to temperature changes are obtained, and negligible structural rearrangement is observed upon heating. These findings are expected to facilitate the rational engineering of versatile TA-based MPN materials with tunable physiochemical properties for diverse applications.

Sustainable management of landfill leachate concentrate via nanofiltration enhanced by one-step rapid assembly of metal-organic coordination complexes

Sustainable treatment of the highly saline landfill leachate concentrate for application as green fertilizer calls for effective fractionation of the existing humic substances and inorganic salts; advanced selective nanofiltration membranes are proposed for this. One-step, rapid assembly of a tannic acid-Fe3+ coordination complex is a promising strategy to endow the membranes with an enhanced nanofiltration performance. In this study, a robust and homogeneous tannic acid-Fe3+ coordination complex layer was effectively coated onto the surface of a loose nanofiltration substrate in an extremely short time (15 s). After the coating of the tannic acid-Fe3+ coordination complex layer, the nanofiltration membrane showed a significantly reduced molecule weight cutoff (i.e., reduction from 601 to 279 Da) and thus enhanced selectivity towards humic substances. Specifically, the rejection to humic substances of the coated nanofiltration membrane increased from 95.31±0.54% to 99.32±0.18% with negligible rise in salt rejection, demonstrating an enhanced fractionation efficacy for humic substances and salts. Assisted by a diafiltration operation with the coated nanofiltration membrane, humic substances in the landfill leachate concentrate were effectively purified and extracted with 96.60% recovery. Particularly, the humic substances were linearly enriched by ca. 7.8 folds (i.e., from 1837 to 13970 mg·L−1) with a purity of 98.91% for potential application as liquid fertilizer. The one-step rapid tannic acid-Fe3+ coordination complex coating exhibits an impressive efficacy to engineer advanced nanofiltration membranes that could be applied at a large scale for sustainable resource extraction from landfill leachate concentrate.

One-step self-assembly of magnetic supramolecular metal-organic coordination functionalized MoS2 complex as nanoenzyme-reactor

In the present study, a kind of magnetic supramolecular metal-organic coordination complex (SMOCC) functionalized MoS2 was prepared with one-step in aqueous solution for enzyme immobilization. As possessing a protective nanocoating of PDA/PEI/Cu2+ (polydopamine: PDA, polyethyleneimine: PEI), the proposed material can provide biocompatible microenvironment and flexible adhesion force on particle interface, which is conductive to loading laccase (170.0 ± 1.8 mg/g) with high activity (93.0 ± 1.1 %). Compared with the free laccase, the immobilized laccase has higher stability in a broader range of pH (3–10), temperature (20−80 °C), storage time (1–18 days) and reusability (1–16 cycles). The removal of carcinogenic persistent organic pollutant malachite green in the water with the immobilized laccase shows a higher efficiency (89.4 ± 1.2 %) than free laccase (16.2 ± 0.2 %). The Fe3O4@MoS2@(PDA/PEI/Cu2+) nanocomposites can also be used successfully to immobilize trypsin, lipase and catalase respectively, showing a satisfactory enzyme loading (157.0 ± 0.1 mg/g, 151.6 ± 1.4 mg/g, 162.6 ± 1.6 mg/g, respectively) and activity (95.0 ± 0.5 %, 90.0 ± 0.8 %, 91.0 ± 0.9 %, respectively). The MoS2 can be replaced by carbon material and similar results can be obtained.

Solid-state nuclear magnetic resonance study of polymorphism in tris(8-hydroxyquinolinate)aluminium.

Tris(8-hydroxyquinolinate)aluminium (Alq3 ) is a metal-organic coordination complex, which is a widely used electroluminescent material in organic light-emitting diode technology. Crystalline Alq3 is known to occur in five polymorphic forms (denoted α, β, γ, δ, and ε), although the structures of some of these polymorphs have been the subject of considerable debate. In particular, the structure of α-Alq3 , which is a model for the local structure in amorphous films used in devices, is highly complex and has never been conclusively solved. In this work, we use solid-state nuclear magnetic resonance (NMR) and density functional theory (DFT) calculations to investigate the local structure of four Alq3 samples. We find that the first structure proposed for α-Alq3 is inconsistent with all of the samples studied, and DFT calculations further suggest that this structure is energetically unfavourable. Instead, samples containing the meridional (mer) isomeric form are found to contain local structures consistent with ε-Alq3 , and a sample containing the facial (fac) isomeric form is consistent with a mixture of γ-Alq3 and δ-Alq3 . We also investigate the influence of different strategies for dispersion correction in DFT geometry optimisations. We find that a recently proposed modified semiempirical dispersion correction scheme gives good agreement with experiment. Furthermore, the DFT calculations also show that distinction between mer and fac isomers on the basis of ηQ that has been assumed in previous work is not always justified.

Two Cd(II) Complexes Based on Carboxylate and Bis(imidazolyl) Ligands: Syntheses, Crystal Structures and Luminescence Properties

Two new metal–organic coordination complexes, {[Cd8(tdc)8(bbi)8(H2O)8]·4DMF]}n (1) and {[Cd(cbba)2(m-bix)2]}n (2) (H2tdc = 2,5-thiophenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis (imidazole), Hcbba = 2-(4-chlorobenzoyl)benzoic acid, m-bix = 1,3-bis((1H-imidazolyl)-methyl) benzene) were synthesized under hydrothermal conditions and characterized by techniques of single-crystal X-ray diffraction analysis, elemental analysis, powder X-ray diffraction and thermogravimetric analysis (TGA). Single-crystal structure analyses reveal that complex 1 displays a 3D 4-connected threefold interpenetrating framework with the point symbol of {42·84}. Complex 2 shows a 3D supramolecular architecture via intermolecular hydrogen bonds and intermolecular π⋯π stacking interactions. Furthermore, the luminescence of the two complexes was also studied.

A General Strategy for Hollow Metal-Phytate Coordination Complex Micropolyhedra Enabled by Cation Exchange.

The ability to incorporate functional metal ions (Mn+ ) into metal-organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic-inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation-exchanged synthesis of a diverse range of hollow Mn+ -phytate (PA) micropolyhedra via the use of hollow Co2+ -PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+ , namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+ =Tb3+ , Eu3+ , and Sm3+ ) luminescence from as-prepared hollow Ln3+ -PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+ - and Mn2+ -PA polyhedral complexes were employed as magnetic contrast agents.

A General Strategy for Hollow Metal‐Phytate Coordination Complex Micropolyhedra Enabled by Cation Exchange

AbstractThe ability to incorporate functional metal ions (Mn+) into metal–organic coordination complexes adds remarkable flexibility in the synthesis of multifunctional organic–inorganic hybrid materials with tailorable electronic, optical, and magnetic properties. We report the cation‐exchanged synthesis of a diverse range of hollow Mn+‐phytate (PA) micropolyhedra via the use of hollow Co2+‐PA polyhedral networks as templates at room temperature. The attributes of the incoming Mn+, namely Lewis acidity and ionic radius, control the exchange of the parent Co2+ ions and the degree of morphological deformation of the resulting hollow micropolyhedra. New functions can be obtained for both completely and partially exchanged products, as supported by the observation of Ln3+ (Ln3+=Tb3+, Eu3+, and Sm3+) luminescence from as‐prepared hollow Ln3+‐PA micropolyhedra after surface modification with dipicolinic acid as an antenna. Moreover, Fe3+‐ and Mn2+‐PA polyhedral complexes were employed as magnetic contrast agents.

Gallium maltolate has in vitro antiviral activity against SARS-CoV-2 and is a potential treatment for COVID-19.

BackgroundGallium has demonstrated strong anti-inflammatory activity in numerous animal studies, and has also demonstrated direct antiviral activity against the influenza A H1N1 virus and the human immunodeficiency virus (HIV). Gallium maltolate (GaM), a small metal-organic coordination complex, has been tested in several Phase 1 clinical trials, in which no dose-limiting or other serious toxicity was reported, even at high daily oral doses for several months at a time. For these reasons, GaM may be considered a potential candidate to treat coronavirus disease 2019 (COVID-19), which is caused by the SARS-CoV-2 virus and can result in severe, sometimes lethal, inflammatory reactions. In this study, we assessed the ability of GaM to inhibit the replication of SARS-CoV-2 in a culture of Vero E6 cells.MethodsThe efficacy of GaM in inhibiting the replication of SARS-CoV-2 was determined in a screening assay using cultured Vero E6 cells. The cytotoxicity of GaM in uninfected cells was determined using the Cell Counting Kit-8 (CCK-8) colorimetric assay.ResultsThe results showed that GaM inhibits viral replication in a dose-dependent manner, with the concentration that inhibits replication by 50% (EC50) being about 14 µM. No cytotoxicity was observed at concentrations up to at least 200 µM.ConclusionThe in vitro activity of GaM against SARS-CoV-2, together with GaM’s known anti-inflammatory activity, provide justification for testing GaM in COVID-19 patients.

Organosulfonate Counteranions-A Trapped Coordination Polymer as a High-Output Triboelectric Nanogenerator Material for Self-Powered Anticorrosion.

Selection of the friction electrode materials is crucial to the performance of a triboelectric nanogenerator (TENG). In the present study, a metal-organic coordination complex containing organosulfonate counteranions with electron-donating ability was synthesized through the coordination-driven self-assembly approach under mild reaction conditions and was chosen as a positive electrode material to construct a triboelectric nanogenerator, exhibiting high-output performance with a peak value of short circuit current density of 98.6 μA and an output voltage of 1180 V. As a practical application, it was shown to light up 1488 commercial green LEDs and power an anticorrosion system device to protect metals from corrosion.

RETRACTED ARTICLE: Three New Metal-Organic Coordination Complexes: Crystal Structures and Anticancer Activity in Multiple Myeloma

Three new metal-organic coordination complexes, namely [Cu(4,4′-bipy)2(NCS)2]n (I), [Cu(HCOO)2(4,4′—bipy)] (II), and [Cu(2,2′-bipy)2]2(V6O17) (III) (4,4′-bipy and 2,2′-bipy = 4,4′-bipyridine and 2,2′-bipyridine, respectively) are successfully prepared by using two similar pyridine ligands with different orientations of N atoms under different reaction conditions (slow volatilization for I, solvothermal for II and III). Their structures and compositions are characterized by both single crystal X-ray diffraction and elemental analysis. Additionally, the newly synthesized compounds are evaluated to identify the molecular characteristics contributing to their cytotoxicity. They are tested against three human multiple myeloma cells (NCI-H929, MM1S, and MM1R) with the MTT assay.

Non-Polyamide Based Nanofiltration Membranes Using Green Metal-Organic Coordination Complexes: Implications for the Removal of Trace Organic Contaminants.

Polyamide-based thin film composite (TFC) membranes are generally optimized for salt rejection but not for the removal of trace organic contaminants (TrOCs). The insufficient rejection of TrOCs such as endocrine disrupting compounds (EDCs) by polyamide membranes can jeopardize product water safety in wastewater reclamation. In this study, we report a novel nonpolyamide membrane chemistry using green tannic acid-iron (TA-Fe) complexes to remove TrOCs. The nanofiltration membrane formed at a TA-Fe molar ratio of 1:3 (TA-Fe3) had a continuous thin rejection layer of 10-30 nm in thickness, together with a water permeability of 5.1 Lm2-h-1bar-1 and a Na2SO4 rejection of 89.7%. Meanwhile, this membrane presented significantly higher rejection of EDCs (up to 99.7%) than that of polyamide membranes (up to 81.8%). Quartz crystal microbalance results revealed that the sorption amount of a model EDC, benzylparbaen, by TA-Fe3 layer was nearly 2 orders of magnitude less than that by polyamide, leading to reduced transmission and higher rejection. Further analysis of membrane revealed a much greater water/EDC selectivity of the TA-Fe3 membrane compared to the polyamide membranes.

AIE-active Metal-organic Coordination Complexes Based on Tetraphenylethylene Unit and Their Applications

Tetraphenylethylene (TPE) and its derivatives, as the widely used aggregation-induced emission (AIE) fluorophores, have attracted rapidly growing interest in the fields of material science and biological technology due to their unique light-emitting mechanism—they are nearly non-emissive in dilute solution but emit brilliant fluorescence in the aggregate state because of the restriction of intramolecular motion. Coordination-driven self-assembly, which provides a highly effective method to put the individual chromophores together, is consistent with the AIE mechanism of TPE. During the past few years, some AIE-active metal-organic coordination complexes have been successfully constructed via coordination-driven self-assembly, and their AIE properties and applications have been investigated. In this review, we survey the recent progress on TPE-based metal-organic coordination complexes and their applications in fluorescence sensors, cell imaging, and light-emitting materials. We will introduce them from three different types of structures: metallacycles, metallacages, and metal-organic frameworks (MOFs).

Three new metal-organic coordination complexes: crystal structures and anticancer activity in multiple myeloma

Three new metal-organic coordination complexes, namely [Cu(4,4'-bipy)2(NCS)2]n (I), [Cu(HCOO)2(4,4'-bipy)] (II), and [Cu(2,2'-bipy)2]2(V6O17) (III) (4,4'-bipy and 2,2'-bipy = 4,4'-bipyridine and 2,2'-bipyridine, respectively) are successfully prepared by using two similar pyridine ligands with different orientations of N atoms under different reaction conditions (slow volatilization for I, solvothermal for II and III). Their structures and compositions are characterized by both single crystal X-ray diffraction and elemental analysis. Additionally, the newly synthesized compounds are evaluated to identify the molecular characteristics contributing to their cytotoxicity. They are tested against three human multiple myeloma cells (NCI-H929, MM1S, and MM1R) with the MTT assay.

Synthesis, characterization and adsorption of endrin on composite materials based on metal organic co-ordination complexes and zeolite

Synthesis, characterization and adsorption of endrin on composite materials based on metal organic co-ordination complexes and zeolite

Diverse structural assemblies and influence in morphology of different parameters in a series of 0D and 1D mercury(II) metal–organic coordination complexes by sonochemical process

Four new mercury coordination supramolecular complexes (1D and 0D), [Hg(L)(Br)2]n(1), [Hg(L)(Cl)2]n(2), [Hg(L)(SCN)2]n(3) and [Hg2(L)2(I)4] (4) where L = C6H8N2 (3-picolylamine), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on complexes 1–4 show that Hg2+ ions are 4, 5, 4 and 4-coordinated, respectively. Topological analysis shows that the complexes 1–4 are 2C1, 2,2,4C1, 2C1 and 1,2,4M16-1 net, respectively. Also, by changing counter ions, various structures were obtained: 1–4 (0D and 1D) which are helical chain, linear chain and rectangular molecule. The role of different parameters like temperature, reaction time, power of ultrasound irradiation and concentration of initial reactants on the growth and morphology of the micro-nano structures are studied.

Effect of different nanoscale microelements containing formulations for seed treatment on germination and growth of maize seedlings

Effect of the nutrient formulations for pre-sowing seed treatment on germination and growth of maize seedlings was studied. The formulations comprised separate copper nanoparticles (NanoCu), IET1- based on a Novalon Seed Treatment product, IET2 - based on humate metal-organic-coordination complexes (MOC), Nualgi – based on nano silica, wherein microelements were adsorbed on the surface of the silica nanoparticles, and formulations with microelements in a form of Metal-EDTA complexes, based on commercial fertilizer products of Novalon, Wuxal and Comex companies. Results of the study showed that all the tested formulations, except for the separate nanocopper formulation, demonstrated visibly higher stimulation effects on the maize seedlings growth, among which the nanoscale microelements-containing seeds treatment formulations produced in Institute of Environmental Technology (IET1 and IET2) exhibited the best growth indices although non-significantly differed as compared with the control. The experimental data presented also proved that for obtaining stable stimulation effects on the plant growth kinetics instead of using separate nanosized microelement it is preferable to use complex formulations, wherein besides of microelements there are other components included such as plant regulators, amino- and carboxylic acids, plant protection agents etc.

Nanocoating of Ce-tannic acid metal-organic coordination complex: surface modification of layered Li1.2Mn0.6Ni0.2O2 by CeO2 coating for lithium-ion batteries

As a low-cost and environmentally friendly polyphenol, tannic acid (TA) is also a versatile coating molecule as it can strongly bind to substrates with different shapes (such as film and particle). We prepared metal-organic coordination of TA and Ce ions onto the surface of Li1.2Mn0.6Ni0.2O2 (LMNO) and then calcined to synthesize CeO2-coated LMNO. Various physicochemical characterizations were performed to reveal the phase structure and morphology of the pristine, metal-organic coordination complex (MOC), and CeO2-coated LMNO cathodes. It is found that the CeO2-coating layer with a thin thickness of ~ 10 nm is successfully built on the surface of LMNO, which provide a fast pathway for lithium-ion diffusion. The electrochemical performance measurements were used to identify the correlation between CeO2 modification and structural changes. In comparison with the pristine LMNO, the CeO2-modified sample exhibits superior electrochemical properties in terms of specific capacity, rate capability, and cycling performances. Specifically, the LMNO coated with 1 wt% CeO2 via MOC delivers discharge capacities of 270, 152, and 132 mAh g−1 at the current rates of 0.1, 5, and 8 C, respectively, much higher than the pristine LMNO (235, 97, and 86 mAh g−1, respectively) and the sample by blending method (263, 121, and 90 mAh g−1, respectively). The cyclic performance shows that 78.5% of the initial discharge capacity can be retained after 200 cycles at 1 C. Such enhanced electrochemical performance of the surface-modified LMNO can be attributed to the higher Li+ diffusion rate and the lower electrochemical polarization endowed by the uniform and conductive CeO2-coating layer.

Assembly of Robust Holmium-Directed 2D Metal-Organic Coordination Complexes and Networks on the Ag(100) Surface.

We describe the formation of lanthanide-organic coordination networks and complexes under ultra-high-vacuum conditions on a clean Ag(100) surface. The structures comprise single Ho atoms as coordination centers and 1,4-benzenedicarboxylate (from terephtalic acid, TPA) as molecular linkers. Using low-temperature scanning tunneling microscopy, we find two different chiral phases of surface-supported metal-organic structures incorporating Ho atoms. Density functional theory calculations can explain the structure of both binding motifs and give possible reasons for their varying formation under the respective Ho/TPA ratios, as well as deposition and annealing temperatures. Metal-ligand interactions drive the formation of cloverleaf-shaped mononuclear Ho-TPA4 complexes establishing supramolecular arrays stabilized through hydrogen bonding. A 2D lanthanide-organic reticulation is observed when changing the stoichiometry between the two building blocks. The combined insights from scanning tunneling microscopy and density functional theory reveal the relative stability, charge transfer, and bonding environment of both motifs.