Tailoring the Use of 8-Hydroxyquinolines for the Facile Separation of Iron, Dysprosium and Neodymium.

Permanent magnets (PMs) containing rare earth elements (REEs) can generate energy in a sustainable manner. With an anticipated tenfold increase in REEs demand by 2050, one of the crucial strategies to meet the demand is developing of efficient recycling methods. NdFeB PMs are the most widely employed, however, the similar chemical properties of Nd (20-30 % wt.

Inhibitory interactions of the 2,3-dihydro-6,7-dihydroxy-1H-isoindol-1-one scaffold with Bunyavirales cap-snatching endonucleases expose relevant drug design features.

The World Health Organization (WHO) identifies several bunyaviruses as significant threats to global public health security. Developing effective therapies against these viruses is crucial to combat future outbreaks and mitigate their impact on patient outcomes. Here, we report the synthesis of some isoindol-1-one derivatives and explore their inhibitory properties over an indispensable metal-dependent cap-snatching endonuclease (Cap-ENDO) shared among evolutionary divergent bunyaviruses.

Bifunctional octadentate pseudopeptides as Zirconium-89 chelators for immuno-PET applications.

Background: Positron emission tomography (PET) is a highly sensitive method that provides fine resolution images, useful in the field of clinical diagnostics. In this context, Zirconium-89 (Zr)-based imaging agents have represented a great challenge in molecular imaging with immuno-PET, which employs antibodies (mAbs) as biological vectors. Indeed, immuno-PET requires radionuclides that can be attached to the mAb to provide stable in vivo conjugates, and for this purpose, the radioactive element should have a decay half-life compatible with the time needed for the biodistribution of the immunoglobulin.

Boosting Energy-Transfer Processes via Dispersion Interactions.

The generation of open-shell intermediates under mild conditions has opened broad synthetic opportunities during this century. However, these reactive species often require a case specific and tailored tuning of experimental parameters in order to efficiently convert substrates into products. We report a general approach that can overcome these ubiquitous limitations for several visible-light promoted energy-transfer processes.

Insights on the Structure in Solution of Paramagnetic Ln/Ga 12-Metallacrown-4 Complexes Using 1D H NMR and Model Structures.

The solution structure of LnNa(OBz)[12-MC-4] complexes was studied through paramagnetic H NMR and DFT models. Although isostructural in the solid state, their H NMR spectra in DMSO- are extremely different from one another due to the magnetic anisotropy of the lanthanide(III) ions. NMR data were analyzed by the "all-lanthanide" method that were compared to X-ray structures and model structures, allowing to establish the extent of the structural changes that occur from the solid state to the solution phase.

Semirigid Ligands Enhance Different Coordination Behavior of Nd and Dy Relevant to Their Separation and Recovery in a Non-aqueous Environment.

Rare-earth elements are widely used in high-end technologies, the production of permanent magnets (PMs) being one of the sectors with the greatest current demand and likely greater future demand. The combination of Nd and Dy in NdFeB PMs enhances their magnetic properties but makes their recycling more challenging. Due to the similar chemical properties of Nd and Dy, their separation is expensive and currently limited to the small scale.

Role of the Cysteine in R3 Tau Peptide in Copper Binding and Reactivity.

Tau is a widespread neuroprotein that regulates the cytoskeleton assembly. In some neurological disorders, known as tauopathies, tau is dissociated from the microtubule and forms insoluble neurofibrillary tangles. Tau comprises four pseudorepeats (R1-R4), containing one (R1, R2, R4) or two (R3) histidines, that potentially act as metal binding sites.

Gallium(III)-pyridoxal thiosemicarbazone derivatives as nontoxic agents against Gram-negative bacteria.

Many bacterial strains are developing mechanism of resistance to antibiotics, rendering last-resort antibiotics inactive. Therefore, new drugs are needed and in particular metal-based compounds represent a valid starting point to explore new antibiotic classes. In this study, we have chosen to investigate gallium(III) complexes for their potential antimicrobial activity against different strains of Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa which have developed different type of resistance mechanism, including the expression of β-lactamases (NDM-1, ESβL, or AmpC) or the production of biofilm.

Lanthanide Identity Governs Guest-Induced Dimerization in Ln [15-MC -5]) Metallacrowns.

Series of lanthanide-containing metallic coordination complexes are frequently presented as structurally analogous, due to the similar chemical and coordinative properties of the lanthanides. In the case of chiral (Ln [15-MC -5]) metallacrowns (MCs), which are well established supramolecular hosts, the formation of dimers templated by a dicarboxylate guest (muconate) in solution of neutral pH is herein shown to have a unique dependence on the identity of the MC's central lanthanide. Calorimetric data and nuclear magnetic resonance diffusion studies demonstrate that MCs containing larger or smaller lanthanides as the central metal only form monomeric host-guest complexes whereas analogues with intermediate lanthanides (for example, Eu, Gd, Dy) participate in formation of dimeric host-guest-host compartments.

Toxic metal sequential sequestration in water using new amido-aminoacid ligand as a model for the interaction with polyamidoamines.

Polyamidoamines are low cost and easily synthesized materials that may find applications in cations sequestration and water treatment. In this paper a new amido-aminoacid ligand containing methionine has been designed as a monomeric model of the corresponding polyamidoamine. The amido-aminoacid ligand has been synthesized in high yield, by reacting acrylamide and methionine via aza-Michael addition in water and mild temperature conditions.

Different Behavior of the Histidine Residue toward Cadmium and Zinc in a Cadmium-Specific Metallothionein from an Aquatic Fungus.

Metallothioneins (MTs) are a large superfamily of ubiquitous cysteine-rich metalloproteins with main functions in metal ion homeostasis and detoxification. Neclu_MT1 is a metallothionein from the aquatic fungus and so far the only known MT that is solely induced by Cd but not by Zn or copper ions. In addition to eight cysteine residues, Neclu_MT1 also contains a less common single C-terminal histidine residue.

In vitro and in vivo anticancer activity of tridentate thiosemicarbazone copper complexes: Unravelling an unexplored pharmacological target.

Certain metal complexes can have a great antitumor activity, as the use of cisplatin in therapy has been demonstrating for the past fifty years. Copper complexes, in particular, have attracted much attention as an example of anticancer compounds based on an endogenous metal. In this paper we present the synthesis and the activity of a series of copper(II) complexes with variously substituted salicylaldehyde thiosemicarbazone ligands.

Cu(II) coordination to His-containing linear peptides and related branched ones: Equalities and diversities.

The two branched peptides (AAHAWG)-PWT2 and (HAWG)-PWT2 where synthesized by mounting linear peptides on a cyclam-based scaffold (PWT2), provided with four maleimide chains, through a thio-Michael reaction. The purpose of this study was primarily to verify if the two branched ligands had a Cu(II) coordination behavior reproducing that of the single-chain peptides, namely AAHAWG-NH, which bears an Amino Terminal Cu(II)- and Ni(II)-Binding (ATCUN) Motif, and HAWG-NH, which presents a His residue as the N-terminal amino acid, in a wide pH range. The study of Cu(II) binding was performed by potentiometric, spectroscopic (UV-vis absorption, CD, fluorescence) and ESI-MS techniques.

Binding and Reactivity of Copper to R and R Fragments of tau Protein.

Tau protein is present in significant amounts in neurons, where it contributes to the stabilization of microtubules. Insoluble neurofibrillary tangles of tau are associated with several neurological disorders known as tauopathies, among which is Alzheimer's disease. In neurons, tau binds tubulin through its microtubule binding domain which comprises four imperfect repeats (R-R).

Thermodynamic stability and structure in aqueous solution of the [Cu(PTA)] complex (PTA = aminophosphine‑1,3,5‑triaza‑7‑phosphaadamantane).

The chemistry of copper(I) with water-soluble phosphines is an emergent area of study which has the objective of finding ligands that stabilize copper in its lower oxidation state. Cu(I) has been found relevant in the mechanism of copper transports into cells, and the accessibility of this oxidation state has implications in oxidative stress processes. For these reasons the possibility to deal with stable, water soluble copper(I) is an attractive approach for devising new biologically relevant metal-based drugs and chelating agents.

Elucidation of H NMR Paramagnetic Features of Heterotrimetallic Lanthanide(III)/Manganese(III) 12-MC-4 Complexes.

The paramagnetic one-dimensional H NMR spectra of twelve LnNa(OAc)[12-MC-4] complexes, where Ln is Pr-Yb (except Pm) and Y, are reported. Their solid-state isostructural nature is confirmed in methanol-d solution, as a similar pattern in the H NMR spectra is observed along the series. Notably, a relatively well-resolved spectrum is reported for the Gd complex.

Anti-proliferative effects of copper(II) complexes with hydroxyquinoline-thiosemicarbazone ligands.

The possibility to influence the physiological concentration of copper ions through the careful choice of ligands is emerging as a novel intriguing strategy in the treatment of pathologies such as cancer and Alzheimer. Thiosemicarbazones play an important role in this field, because they offer a wide variety of potential functionalizations and different kinds of coordination modes. Here we report the synthesis of some 8-hydroxyquinoline thiosemicarbazone ligands containing an ONN'S donor set and their Zn(II) and Cu(II) complexes.

Raman and NMR kinetics study of the formation of amidoamines containing N-hydroxyethyl groups and investigations on their Cu(II) complexes in water.

Three amidoamines containing the N-hydroxyethyl group (Et), namely (Et)N(CH)C(O)NH (1), [(Et)N(CH)C(O)NH]CH (2) and EtN[(CH)C(O)NH] (3) have been synthesized by reacting diethanolamine EtNH with acrylamide and N,N'-methylenebisacrylamide (respectively 1 and 2) and ethanolamine EtNH with acrylamide (3). Four other compounds corresponding to 1 and 2, but derived from sec-amines MeNH (4 and 5) and EtNH (6 and 7) have been prepared for the sake of comparison of the spectroscopic features. All compounds have been obtained by the well-known aza-Michael addition between an N-nucleophile and an activated vinyl group.

Insights into the cytotoxic activity of the phosphane copper(I) complex [Cu(thp)][PF].

The phosphane Cu(I) complex [Cu(thp)][PF], 1 (thp=tris(hydroxymethyl)phosphane) shows notable in vitro antitumour activity against a wide range of solid tumours. Uptake experiments performed in 1-treated colon cancer cells by atomic absorption spectrometry, reveal that the antiproliferative activity is consistent with the intracellular copper content. The solution chemistry of this agent, investigated by means of X-ray Absorption Spectroscopy and spectrophotometric titrations in aqueous media, indicates that 1 is labile giving coordinative unsaturated [Cu(thp)] species (n=3 and 2) at micromolar concentrations.

Design of 2D Porous Coordination Polymers Based on Metallacrown Units.

A 12-metallacrown-4 (MC) complex was designed and employed as the building block in the synthesis of coordination polymers, one of which is the first permanently porous MC architecture. The connection of the four-fold symmetric MC subunits by Cu(II) nodes led to the formation of 2D layers of metallacrowns. Channels are present in the crystalline architecture, which exhibits permanent porosity manifested in N2 and CO2 uptake capacity.

Silver complexation by metallacryptates.

We report the first complete characterization of metallycryptates encapsulating Ag(I) cations: carboxylato ligands derived from l-proline and l-alanine chelate and bridge six Cu(II) centres arranged in a slightly distorted octahedral fashion. Eight oxygen atoms of these ligands are disposed in square-prismatic geometry and coordinate the monovalent cation. Two alternative metallacryptates based on alanine have been identified which differ with respect to aggregation: a solid in which pairs of encapsulating sites are formed competes with an infinite chain of M(I) coordinating sites.

The peculiar behavior of Picha in the formation of metallacrown complexes with Cu(II), Ni(II) and Zn(II) in aqueous solution.

The thermodynamic stability of the metallacrown complexes formed by picolinehydroxamic acid (Picha) with Cu(ii), Ni(ii) and Zn(ii) in aqueous solution has been determined by potentiometry, and the speciation models were validated by ESI-MS and UV-visible spectrophotometry. Cu(ii) and Zn(ii) form 12-MC-4 species as the unique metallacrowns present in the solution. While for Cu(ii) the 12-MC-4 is slightly less stable than that obtained with alaninehydroxamic acid (Alaha), the opposite was found for Zn(ii).

The mechanism of the Cu²⁺[12-MCCu(Alaha)-4] metallacrown formation and lanthanum(III) encapsulation.

A kinetic, calorimetric, mass spectrometry and EPR study has been performed on the formation of the metallacrown Cu(2+)[12-MCCu(Alaha)-4] from Cu(ii) and α-alaninehydroxamic acid (H2L). The acidity range where Cu(2+)[12-MCCu(Alaha)-4] is stable lies between pH 3.5 and 6.