Reactions of Cadmium(II) Halides and Di-2-Pyridyl Ketone Oxime: One-Dimensional Coordination Polymers.

The coordination chemistry of 2-pyridyl ketoximes continues to attract the interest of many inorganic chemistry groups around the world for a variety of reasons. Cadmium(II) complexes of such ligands have provided models of solvent extraction of this toxic metal ion from aqueous environments using 2-pyridyl ketoxime extractants. Di-2-pyridyl ketone oxime (dpkoxH) is a unique member of this family of ligands because its substituent on the oxime carbon bears another potential donor site, i.e., a second 2-pyridyl group. The goal of this study was to investigate the reactions of cadmium(II) halides and dpkoxH in order to assess the structural role (if any) of the halogeno ligand and compare the products with their zinc(II) analogs. The synthetic studies provided access to complexes {[CdCl2(dpkoxH)∙2H2O]}n (1∙2H2O), {[CdBr2(dpkoxH)]}n (2) and {[CdI2(dpkoxH)]}n (3) in 50-60% yields. The structures of the complexes were determined by single-crystal X-ray crystallography. The compounds consist of structurally similar 1D zigzag chains, but only 2 and 3 are strictly isomorphous. Neighboring CdII atoms are alternately doubly bridged by halogeno and dpkoxH ligands, the latter adopting the η1:η1:η1:µ (or 2.0111 using Harris notation) coordination mode. A terminal halogeno group completes distorted octahedral coordination at each metal ion, and the coordination sphere of the CdII atoms is {CdII(η1 - X)(µ - X)2(Npyridyl)2(Noxime)} (X = Cl, Br, I). The trans-donor-atom pairs in 1∙2H2O are Clterminal/Noxime and two Clbridging/Npyridyl; on the contrary, these donor-atom pairs are Xterminal/Npyridyl, Xbridging/Noxime, and Xbridging/Npyridyl (X = Br, I). There are intrachain H-bonding interactions in the structures. The packing of the chains in 1∙2H2O is achieved via π-π stacking interactions, while the 3D architecture of the isomorphous 2 and 3 is built via C-H∙∙∙Cg (Cg is the centroid of one pyridyl ring) and π-π overlaps. The molecular structures of 1∙2H2O and 2 are different compared with their [ZnX2(dpkoxH)] (X = Cl, Br) analogs. The polymeric compounds were characterized by IR and Raman spectroscopies in the solid state, and the data were interpreted in terms of the known molecular structures. The solid-state structures of the complexes are not retained in DMSO, as proven via NMR (1H, 13C, and 113Cd NMR) spectroscopy and molar conductivity data. The complexes completely release the coordinated dpkoxH molecule, and the dominant species in solution seem to be [Cd(DMSO)6]2+ in the case of the chloro and bromo complexes and [CdI2(DMSO)4].

Confirming the Molecular Basis of the Solvent Extraction of Cadmium(II) Using 2-Pyridyl Oximes through a Synthetic Inorganic Chemistry Approach and a Proposal for More Efficient Extractants.

The present work describes the reactions of CdI2 with 2-pyridyl aldoxime (2paoH), 3-pyridyl aldoxime (3paoH), 4-pyridyl aldoxime (4paoH), 2-6-diacetylpyridine dioxime (dapdoH2) and 2,6-pyridyl diamidoxime (LH4). The primary goal was to contribute to understanding the molecular basis of the very good liquid extraction ability of 2-pyridyl ketoximes with long aliphatic chains towards toxic Cd(II) and the inability of their 4-pyridyl isomers for this extraction. Our systematic investigation provided access to coordination complexes [CdI2(2paoH)2] (1), {[CdI2(3paoH)2]}n (2), {[CdI2(4paoH)2]}n (3) and [CdI2(dapdoH2)] (4). The reaction of CdI2 and LH4 in EtOH resulted in a Cd(II)-involving reaction of the bis(amidoxime) and isolation of [CdI2(L'H2)] (5), where L'H2 is the new ligand 2,6-bis(ethoxy)pyridine diimine. A mechanism of this transformation has been proposed. The structures of 1, 2, 3, 4·2EtOH and 5 were determined by single-crystal X-ray crystallography. The complexes have been characterized by FT-IR and FT-Raman spectra in the solid state and the data are discussed in terms of structural features. The stability of the complexes in DMSO was investigated by 1H NMR spectroscopy. Our studies confirm that the excellent extraction ability of 2-pyridyl ketoximes is due to the chelating nature of the extractants leading to thermodynamically stable Cd(II) complexes. The monodentate coordination of 4-pyridyl ketoximes (as confirmed in our model complexes with 4paoH and 3paoH) seems to be responsible for their poor performance as extractants.

Novel Co5 and Ni4 Metal Complexes and Ferromagnets by the Combination of 2-Pyridyl Oximes with Polycarboxylic Ligands.

The use of 2-pyridyl oximes in metal complexes chemistry has been extensively investigated in the last few decades as a fruitful source of species with interesting magnetic properties. In this work, the initial combination of pyridine-2-amidoxime (pyaoxH2) and 2-methyl pyridyl ketoxime (mpkoH) with isonicotinic acid (HINA) and 3,5-pyrazole dicarboxylic acid (H3pdc) has provided access to three new compounds, [Ni4(INA)2(pyaox)2(pyaoxH)2(DMF)2] (1), [Co5(mpko)6(mpkoH)2(OMe)2(H2O)](ClO4)6 (2), and [Co5(OH)(Hpdc)5(H2pdc)] (3). 1 displays a square-planar metal topology, being the first example that bears simultaneously HINA and pyaoxH2 in their neutral or ionic form. The neighbouring Ni4 units in 1 are held together through strong intermolecular hydrogen bonding interactions, forming a three-dimensional supramolecular framework. 2 and 3 are mixed-valent Co4IIICoII and Co2IIICoII3 compounds with a bowtie and trigonal bipyramidal metal topology, accordingly. Direct current and alternate current magnetic susceptibility studies revealed that the exchange interactions between the NiII ions in 1 are ferromagnetic (J = 1.79(4) cm-1), while 2 exhibits weak AC signals in the presence of a magnetic field. The syntheses, crystal structures, and magnetic properties of 1-3 are discussed in detail.

Pentanuclear Thorium(IV) Coordination Cluster from the Use of Di(2-pyridyl) Ketone.

The Th(NO3)4·5H2O/di(2-pyridyl) ketone [(py)2CO] reaction system gives a pentanuclear cluster containing the doubly deprotonated form of the gem-diol derivative of the ligand. The cluster consists of a tetrahedral arrangement of four ThIV ions centered on the fifth ion, which is the first characterized ThIV5 complex. The analysis of its structure reveals that this is a Kuratowski-type coordination compound.

Indium(III) in the "Periodic Table" of Di(2-pyridyl) Ketone: An Unprecedented Transformation of the Ligand and Solid-State 115In NMR Spectroscopy as a Valuable Structural Tool.

Reactions of di(2-pyridyl) ketone, (py)2CO, with indium(III) halides in CH3NO2 have been studied, and a new transformation of the ligand has been revealed. In the presence of InIII, the C═O bond of (py)2CO is subjected to nucleophilic attack by the carbanion -:CH2NO2, yielding the dinuclear complexes [In2X4{(py)2C(CH2NO2)(O)}2] (X = Cl, 1; X = Br, 2; X = I, 3) in moderate to good yields. The alkoxo oxygens of the two η1:η2:η1-(py)2C(CH2NO2)(O)- ligands doubly bridge the InIII centers and create a {In2(µ2-OR)2}4+ core. Two pyridyl nitrogens of different organic ligands and two terminal halogeno ions complete a distorted-octahedral stereochemistry around each In(III) ion. After maximum excitation at 360 or 380 nm, the solid chloro complex 1 emits blue light at 420 and 440 nm at room temperature, the emission being attributed to charge transfer within the coordinated organic ligand. Solid-state 115In NMR spectra, in combination with DFT calculations, of 1-3 have been studied in detail at both 9.4 and 14.1 T magnetic fields. The nuclear quadrupolar and chemical shift parameters provide valuable findings concerning the electric field gradients and magnetic shielding at the nuclei of indium, respectively. The experimentally derived CQ values are 40 ± 3 MHz for 1, 46 ± 5 MHz for 2, and 50 ± 10 and 64 ± 7 MHz for the two crystallographically independent InIII sites for 3, while the δiso values fall in the range 130 ± 30 to -290 ± 60 ppm. The calculated CQ and asymmetry parameter (ηQ) values are fully consistent with the experimental values for 1 and 2 and are in fairly good agreement for 3. The results have been analyzed and discussed in terms of the known (1, 3) and proposed (2) structural features of the complexes, demonstrating that 115In NMR is an effective solid-state technique for the study of indium(III) complexes.

Dinuclear Lanthanide(III) Complexes from the Use of Methyl 2-Pyridyl Ketoxime: Synthetic, Structural, and Physical Studies.

The first use of methyl 2-pyridyl ketoxime (mepaoH) in homometallic lanthanide(III) [Ln(III)] chemistry is described. The 1:2 reactions of Ln(NO3)3·nH2O (Ln = Nd, Eu, Gd, Tb, Dy; n = 5, 6) and mepaoH in MeCN have provided access to complexes [Ln2(O2CMe)4(NO3)2(mepaoH)2] (Ln = Nd, 1; Ln = Eu, 2; Ln = Gd, 3; Ln = Tb, 4; Ln = Dy, 5); the acetato ligands derive from the LnIII-mediated hydrolysis of MeCN. The 1:1 and 1:2 reactions between Dy(O2CMe)3·4H2O and mepaoH in MeOH/MeCN led to the all-acetato complex [Dy2(O2CMe)6(mepaoH)2] (6). Treatment of 6 with one equivalent of HNO3 gave 5. The structures of 1, 5, and 6 were solved by single-crystal X-ray crystallography. Elemental analyses and IR spectroscopy provide strong evidence that 2-4 display similar structural characteristics with 1 and 5. The structures of 1-5 consist of dinuclear molecules in which the two LnIII centers are bridged by two bidentate bridging (η1:η1:µ2) and two chelating-bridging (η1:η2:µ2) acetate groups. The LnIII atoms are each chelated by a N,N'-bidentate mepaoH ligand and a near-symmetrical bidentate nitrato group. The molecular structure of 6 is similar to that of 5, the main difference being the presence of two chelating acetato groups in the former instead of the two chelating nitrato groups in the latter. The geometry of the 9-coordinate LnIII centers in 1, 5 and 6 can be best described as a muffin-type (MFF-9). The 3D lattices of the isomorphous 1 and 5 are built through H-bonding, π⋯π stacking and C-H⋯π interactions, while the 3D architecture of 6 is stabilized by H bonds. The IR spectra of the complexes are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The Eu(III) complex 2 displays a red, metal-ion centered emission in the solid state; the TbIII atom in solid 4 emits light in the same region with the ligand. Magnetic susceptibility studies in the 2.0-300 K range reveal weak antiferromagnetic intramolecular GdIII…GdIII exchange interactions in 3; the J value is -0.09(1) cm-1 based on the spin Hamiltonian H = -J(SGd1·SGd2).

Oligonuclear Actinoid Complexes with Schiff Bases as Ligands-Older Achievements and Recent Progress.

Even 155 years after their first synthesis, Schiff bases continue to surprise inorganic chemists. Schiff-base ligands have played a major role in the development of modern coordination chemistry because of their relevance to a number of interdisciplinary research fields. The chemistry, properties and applications of transition metal and lanthanoid complexes with Schiff-base ligands are now quite mature. On the contrary, the coordination chemistry of Schiff bases with actinoid (5f-metal) ions is an emerging area, and impressive research discoveries have appeared in the last 10 years or so. The chemistry of actinoid ions continues to attract the intense interest of many inorganic groups around the world. Important scientific challenges are the understanding the basic chemistry associated with handling and recycling of nuclear materials; investigating the redox properties of these elements and the formation of complexes with unusual metal oxidation states; discovering materials for the recovery of trans-{UVIO2}2+ from the oceans; elucidating and manipulating actinoid-element multiple bonds; discovering methods to carry out multi-electron reactions; and improving the 5f-metal ions' potential for activation of small molecules. The study of 5f-metal complexes with Schiff-base ligands is a currently "hot" topic for a variety of reasons, including issues of synthetic inorganic chemistry, metalosupramolecular chemistry, homogeneous catalysis, separation strategies for nuclear fuel processing and nuclear waste management, bioinorganic and environmental chemistry, materials chemistry and theoretical chemistry. This almost-comprehensive review, covers aspects of synthetic chemistry, reactivity and the properties of dinuclear and oligonuclear actinoid complexes based on Schiff-base ligands. Our work focuses on the significant advances that have occurred since 2000, with special attention on recent developments. The review is divided into eight sections (chapters). After an introductory section describing the organization of the scientific information, Sections 2 and 3 deal with general information about Schiff bases and their coordination chemistry, and the chemistry of actinoids, respectively. Section 4 highlights the relevance of Schiff bases to actinoid chemistry. Sections 5-7 are the "main menu" of the scientific meal of this review. The discussion is arranged according the actinoid (only for Np, Th and U are Schiff-base complexes known). Sections 5 and 7 are further arranged into parts according to the oxidation states of Np and U, respectively, because the coordination chemistry of these metals is very much dependent on their oxidation state. In Section 8, some concluding comments are presented and a brief prognosis for the future is attempted.

Asymmetric Dinuclear Lanthanide(III) Complexes from the Use of a Ligand Derived from 2-Acetylpyridine and Picolinoylhydrazide: Synthetic, Structural and Magnetic Studies.

A family of four Ln(III) complexes has been synthesized with the general formula [Ln2(NO3)4(L)2(S)] (Ln = Gd, Tb, Er, and S = H2O; 1, 2 and 4, respectively/Ln = Dy, S = MeOH, complex 3), where HL is the flexible ditopic ligand N'-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide. The structures of isostructural MeOH/H2O solvates of these complexes were determined by single-crystal X-ray diffraction. The two LnIII ions are doubly bridged by the deprotonated oxygen atoms of two "head-to-head" 2.21011 (Harris notation) L¯ ligands, forming a central, nearly rhombic {LnIII2(µ-OR)2}4+ core. Two bidentate chelating nitrato groups complete a sphenocoronal 10-coordination at one metal ion, while two bidentate chelating nitrato groups and one solvent molecule (H2O or MeOH) complete a spherical capped square antiprismatic 9-coordination at the other. The structures are critically compared with those of other, previously reported metal complexes of HL or L¯. The IR spectra of 1-4 are discussed in terms of the coordination modes of the organic and inorganic ligands involved. The f-f transitions in the solid-state (diffuse reflectance) spectra of the Tb(III), Dy(III), and Er(III) complexes have been fully assigned in the UV/Vis and near-IR regions. Magnetic susceptibility studies in the 1.85-300 K range reveal the presence of weak, intramolecular GdIII∙∙∙GdIII antiferromagnetic exchange interactions in 1 [J/kB = -0.020(6) K based on the spin Hamiltonian H = -2J(SGd1∙ SGd2)] and probably weak antiferromagnetic LnIII∙∙∙LnIII exchange interactions in 2-4. Ac susceptibility measurements in zero dc field do not show frequency dependent out-of-phase signals, and this experimental fact is discussed for 3 in terms of the magnetic anisotropy axis for each DyIII center and the oblate electron density of this metal ion. Complexes 3 and 4 are Single-Molecule Magnets (SMMs) and this behavior is optimally observed under external dc fields of 600 and 1000 Oe, respectively. The magnetization relaxation pathways are discussed and a satisfactory fit of the temperature and field dependencies of the relaxation time τ was achieved considering a model that employs Raman, direct, and Orbach relaxation mechanisms.

A Known Iron(II) Complex in Different Nanosized Particles: Variable-Temperature Raman Study of Its Spin-Crossover Behavior.

The spin-crossover (SCO) polymorph B (complex 1) of the known compound [FeII{N(CN)2}2(abpt)2], where abpt is 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, has been prepared in three different particle sizes averaging ∼300 (sample 1a), ∼80 (sample 1b), and ∼20 nm (sample 1c). Two independent octahedral molecules possessing Fe1 and Fe2 were found to be present in the crystal of B. Magnetostructural relationships had established that at room temperature both FeII sites are in the high-spin state (HS-HS), whereas a decrease in the temperature to 90 K induces the complete high-spin to low-spin conversion of the Fe1 site, with Fe2 remaining in the high-spin state (LS-HS). The three samples have been characterized by elemental analyses, ATR spectra, solution UV/vis spectra (to exclude resonance Raman effects) and powder X-ray diffraction patterns, while their morphological characteristics have been examined by scanning electron microscopy (SEM). The SCO behavior of the originally prepared sample 1a has been monitored in detail by variable-temperature Raman studies in the 300-80 K range using mainly low-frequency ν(Fe-N) and δ(NFeN) modes and the ν(C≡N) mode of the axial dicyanamido groups as spin-sensitive vibrations. The new peaks that appear in the low-temperature Raman spectra of the LS-HS form of the complex are reproduced in the calculated spectrum of the LS state of [FeII{N(CN)2}2(abpt)2]. The influence of the average particle size on the SCO properties of 1 has also been studied by variable-temperature Raman spectra. The studies indicate that, during the HS-HS → LS-HS transition, the latter form of the complex appears at higher temperatures for the smaller particles; the T1/2 shift accomplished by manipulating the particle size within a range of roughly 1 order of magnitude (300-20 nm) may be as high as ∼30 K. The SCO features of 1, as deduced from the Raman study, are in excellent agreement with those derived from a traditional variable-temperature magnetic susceptibility study, indicating the utility of the former.

Multifunctionality in Two Families of Dinuclear Lanthanide(III) Complexes with a Tridentate Schiff-Base Ligand.

The employment of N-(2-carboxyphenyl)salicylideneimine in 4f metal chemistry has led to two families of dinuclear complexes depending on the lanthanide(III) used. Representative members exhibit interesting magnetic, optical, and catalytic properties.

Modeling the Solvent Extraction of Cadmium(II) from Aqueous Chloride Solutions by 2-pyridyl Ketoximes: A Coordination Chemistry Approach.

The goal of this work is to model the nature of the chemical species [CdCl2(extractant)2] that are formed during the solvent (or liquid-liquid) extraction of the toxic cadmium(II) from chloride-containing aqueous media using hydrophobic 2-pyridyl ketoximes as extractants. Our coordination chemistry approach involves the study of the reactions between cadmium(II) chloride dihydrate and phenyl 2-pyridyl ketoxime (phpaoH) in water-containing acetone. The reactions have provided access to complexes [CdCl2(phpaoH)2]∙H2O (1∙H2O) and {[CdCl2(phpaoH)]}n (2); the solid-state structures of which have been determined by single-crystal X-ray crystallography. In both complexes, phpaoH behaves as an N,N'-bidentate chelating ligand. The complexes have been characterized by solid-state IR and Raman spectra, and by solution 1H NMR spectra. The preparation and characterization of 1∙H2O provide strong evidence for the existence of the species [CdCl2(extractant)2] that have been proposed to be formed during the liquid-liquid extraction process of Cd(II), allowing the efficient transfer of the toxic metal ion from the aqueous phase into the organic phase.

Heterometallic MnIII4Ln2 (Ln = Dy, Gd, Tb) Cross-Shaped Clusters and Their Homometallic MnIII4MnII2 Analogues.

The employment of di-2-pyridyl ketone, (py)2CO, in heterometallic Mn/4f and homometallic Mn cluster chemistry has yielded six MnIII4Ln2 and two MnIII4MnII2 structurally related clusters, namely, [Mn4Ln2O2{(py)2CO2}4(NO3)2(RCO2)2(H2O)6](NO3)2 (Ln = Gd, 1, 5; Dy, 2; Tb, 3; R = Et, 1-3; Me, 5), [Mn4Dy2O2{(py)2CO2}4(NO3)4(EtCO2)2(H2O)3(MeOH)]·0.7MeOH·0.8H2O (4·0.7MeOH·0.8H2O), [Mn4Gd2O2{(py)2CO2}4(NO3)4(C6H4ClCO2)2(MeOH)2(py)2]·2MeOH (6·2MeOH), [Mn6O2{(py)2CO2}4(py)4(H2O)4](ClO4)4·4H2O (7·4H2O), and [Mn6O2{(py)2CO2}4(NO3)4(py)4] (8), where (py)2CO22- is the dianion of the gem-diol derivative of (py)2CO. The compounds possess a new type of cross-shaped structural core, which in the case of 1-6 is essentially planar, whereas in 7 and 8 it deviates from planarity. Clusters 1-6 are rare examples of Mn/4f species bearing (py)2CO or its derivatives, despite the fact that this ligand has been well-studied and proven a rich source of more than 200 metal compounds so far. Variable-temperature, solid-state direct-current and alternating-current magnetization studies were performed on complexes 1-5, 7, and 8 revealing that the dominant exchange interactions between the metal ions are antiferromagnetic and indicating ground-state spin values of S = 5 (for 1), 6 (for 5), and 2 (for 7 and 8).

Nonemployed Simple Carboxylate Ions in Well-Investigated Areas of Heterometallic Carboxylate Cluster Chemistry: A New Family of {Cu(II)4Ln(III)8} Complexes Bearing tert-Butylacetate Bridging Ligands.

The first use of tert-butylacetate as bridging ligand in 3d/4f-metal cluster chemistry, in conjunction with the versatile chelate ligand pyridine-2,6-dimethanol, has afforded a new family of [Cu4Ln8(OH)6(NO3)2(O2CCH2Bu(t))16(pdm)4] clusters with unprecedented structures and slow magnetization relaxation for the {Cu(II)4Dy(III)8} member. The molecular structure of representative complex 1 consists of a {Cu(II)4Gd(III)8} cage-like cluster built from two {CuGd3} cubanes which are linked to each other and to two {CuGd} subunits on opposite sides through two η(2):η(2):η(2):µ5 NO3(-) ions. The metal ions are additionally bridged by µ3-OH(-), µ3-OR(-), and µ-OR(-) groups to give an overall [Cu4Gd8(µ5-NO3)2(µ3-OH)6(µ3-OR)2(µ-OR)8](14+) core. Peripheral ligation about the core is provided by the N,O,O-chelating part of the pdm(2-) groups and, more impressively, by the oxygen atoms of 16 bridging Bu(t)CH2CO2(-) ligands; the latter are arranged into five classes, adopting a total of six different binding modes with the metal centers. The combined work demonstrates the ligating flexibility of tert-butylacetate ion and its usefulness in the synthesis of new 3d/4f-metal cluster compounds.

Ni(II)20 "Bowls" from the Use of Tridentate Schiff Bases.

The reactions of N-salicylidene-o-aminophenol or its derivatives and excess of nickel(II) acetate in alcohols have led to Ni(II)20 clusters with an unprecedented "bowl" metal topology.

Molecular nanoscale magnetic refrigerants: a ferrimagnetic {Cu(II)15Gd(III)7} cagelike cluster from the use of pyridine-2,6-dimethanol.

The employment of pyridine-2,6-dimethanol in 3d/4f metal cluster chemistry has afforded a new {Cu(II)15Gd(III)7} cagelike molecule with a beautiful structure built by fused triangular subunits; the compound exhibits an overall ferrimagnetic behavior with an appreciable ground-state spin value and shows promise as a low-temperature magnetic refrigerant.

Dinuclear lanthanide(III) complexes by metal-ion-assisted hydration of di-2-pyridyl ketone azine.

The initial employment of di-2-pyridyl ketone azine in 4f metal chemistry has led to a unique ligand transformation; the resulting anionic ligand is able to bridge two Ln(III) ions, affording neutral and cationic dinuclear complexes with interesting properties.

Structural modeling of protein ensembles between E3 RING ligases and SARS-CoV-2: The role of zinc binding domains.

BACKGROUND: The ubiquitin system is a modification process with many different cellular functions including immune signaling and antiviral functions. E3 ubiquitin ligases are enzymes that recruit an E2 ubiquitin-conjugating enzyme bound to ubiquitin in order to catalyze the transfer of ubiquitin from the E2 to a protein substrate. The RING E3s, the most abundant type of ubiquitin ligases, are characterized by a zinc (II)-binding domain called RING (Really Interesting New Gene). Viral replication requires modifying and hijacking key cellular pathways within host cells such as cellular ubiquitination. There are well-established examples where a viral proteins bind to RING E3s, redirecting them to degrade otherwise long-lived host proteins or inhibiting E3's ubiquitination activity. Recently, three binary interactions between SARS-CoV-2 proteins and innate human immune signaling Ε3 RING ligases: NSP15-RNF41, ORF3a-TRIM59 and NSP9-MIB1 have been experimentally established. METHODS: In this work, we have investigated the mode of the previous experimentally supported NSP15-RNF41, ORF3a,-TRIM59 and NSP9-MIB1 binary interactions by in silico methodologies intending to provide structural insights of E3-virus interplay that can help identify potential inhibitors that could block SARS-CoV-2 infection of immune cells. CONCLUSION: In silico methodologies have shown that the above human E3 ligases interact with viral partners through their Zn(II) binding domains. This RING mediated formation of stable SARS-CoV-2-E3 complexes indicates a critical structural role of RING domains in immune system disruption by SARS-CoV-2-infection. DATA AVAILABILITY: The data used to support the findings of this research are included within the article and are labeled with references.

Multifunctional role of zinc in human health: an update.

Zinc is a multipurpose trace element for the human body, as it plays a crucial part in various physiological processes, such as cell growth and development, metabolism, cognitive, reproductive, and immune system function. Its significance in human health is widely acknowledged, and this has led the scientific community towards more research that aims to uncover all of its beneficial properties, especially when compared to other essential metal ions. One notable area where zinc has shown beneficial effects is in the prevention and treatment of various diseases, including cancer. This review aims to explain the involvement of zinc in specific health conditions such as cancer, coronavirus disease 2019 (COVID-19) and neurological disorders like Alzheimer's disease, as well as its impact on the gut microbiome.

Heterometallic clusters based on an uncommon asymmetric "V-shaped" [Fe3+(µ-OR)Ln3+(µ-OR)2Fe3+]6+ (Ln = Gd, Tb, Dy, Ho) structural core and the investigation of the slow relaxation of the magnetization behaviour of the [Fe2Dy] analogue.

The synthesis, crystal structures, Mössbauer spectra and variable temperature dc and ac magnetic susceptibility studies of a new family of trinuclear heterometallic Fe3+/Ln3+ complexes, [Fe2Ln(PhCO2)3((py)2CO2)((py)2C(OMe)O)2(NO3)Cl] (Ln = Gd (1/Gd), Tb (1/Tb), Dy (1/Dy), and Ho (1/Ho)), where (py)2CO22- and (py)2C(OMe)O- are the anions of the gem-diol and hemiketal derivatives of di-2-pyridyl ketone, are reported. Compounds 1/Ln are based on an asymmetric "V-shaped" [Fe3+(µ-OR)Ln(µ-OR)2Fe3+]6+ structural core formed from the connection of the two terminal Fe3+ centers to the central Ln3+ ion either through one or two alkoxide groups originating from the alkoxide-type bridging ligands. Direct current magnetic susceptibility studies reveal the presence of weak antiferromagnetic interactions between the Fe3+ ions. Alternating current magnetic studies indicate the presence of a slow-magnetic relaxation process in 1/Dy with an energy barrier Ueff = 6.7 (±0.3) K and a pre-exponential factor, τ0 = 2.2 (±0.4) × 10-7 s. The electronic, magnetic and relaxation properties of the complexes were further monitored by variable temperature 57Fe Mössbauer spectroscopy. At T > 80 K the spectra from the complexes comprise two quadrupole doublets the hyperfine parameters of which reflect the distinct coordination environment of the two Fe3+ terminal sites. At T < 20 K, the Mössbauer spectra for 1/Dy are affected by magnetic relaxation effects. At 1.5 K, the spectrum of 1/Dy comprises well defined magnetic sextets indicating relaxation times slower than the characteristic time of the Mössbauer technique (10-7 s) in agreement with the dynamic magnetic measurements. 1/Gd exhibits broad unresolved magnetic sextets at 1.5 K indicating that the spin relaxation time is of the order of the Mössbauer characteristic time at this temperature. For 1/Tb, 1/Ho the Mössbauer spectra exhibit slight broadening even at the lowest available temperature consistent with magnetic relaxation times less than 10-7 s.

Interesting chemical and physical features of the products of the reactions between trivalent lanthanoids and a tetradentate Schiff base derived from cyclohexane-1,2-diamine.

The initial use of a tetradentate Schiff base (LH2) derived from the 2 : 1 condensation between 2-hydroxyacetophenone and cyclohexane-1,2-diamine in 4f-metal chemistry is described. The 1 : 2 reaction of Ln(NO3)3·xH2O (Ln = lanthanoid or yttrium) and LH2 in MeOH/CH2Cl2 has provided access to isostructural complexes [Ln(NO3)3(L'H2)(MeOH)] in moderate to good yields. Surprisingly, the products contain the corresponding Schiff base ligand L'H2 possessing six aliphatic -CH2- groups instead of the -CH-(CH2)4-CH- unit of the cyclohexane ring, i.e. an unusual ring-opening of the latter has occurred. A mechanism for this LnIII-assisted/promoted LH2 → L'H2 transformation has been proposed assuming transient LnII species and a second LH2 molecule as the H2 source for the reduction of the cyclohexane moiety. DFT calculations provide strong evidence for the great thermodynamic stability of the products in comparison with analogous complexes containing the original intact ligand. The structures of the PrIII, SmIII, GdIII, TbIII, and HoIII complexes have been determined by single-crystal X-ray crystallography. The 9-coordinate LnIII centre in the molecules is bound to six oxygen atoms from the three bidentate chelating nitrato groups, two oxygen atoms that belong to the bidentate chelating organic ligand, and one oxygen atom from the coordinated MeOH group. In the overall neutral bis(zwitterionic) L'H2 ligand, the acidic H atoms are clearly located on the imino nitrogen atoms and this results in the formation of an unusual 16-membered chelating ring. The coordination polyhedra defined by the nine donor atoms around the 4f-metal-ion centres can be best described as distorted, spherical capped square antiprisms. The EuIII, TbIII, and DyIII complexes exhibit LnIII-based luminescence in the visible region, with the coordinated L'H2 molecule acting as the antenna. Ac magnetometry experiments show that the DyIII member of the family behaves as an SIM at zero field and under external dc fields of 0.1 and 0.2 T without the enhancement of the peaks' maxima, suggesting that QTM is not the relaxation path. The GdIII complex behaves, rather unexpectedly, as a SIM with two different magnetic relaxation paths occurring at very close temperatures; this behaviour is tentatively attributed to a very small axial zero-field splitting (D ∼ 0.1 cm-1), which cannot be detected by magnetization or susceptibility experiments. The prospects of the present, first results in the lanthanoid(III)-LH2 chemistry are discussed.