Highly water-soluble dimeric and trimeric lanthanide carbonates with ethylenediaminetetraacetates as precursors of catalysts for the oxidative coupling reaction of methane

Highly water-soluble dimeric and trimeric lanthanide carbonates with ethylenediaminetetraacetates have been obtained. Their coordination modes provide a model for the oxidative coupling of methane of lanthanide carbonates.

Experimental and DFT studies of gadolinium decorated graphene oxide materials for their redox properties and as a corrosion inhibition barrier layer on Mg AZ13 alloy in a 3.5% NaCl environment

Magnesium alloys are broadly used worldwide in various applications; however, the serious disadvantage of these alloys are subject to corrosion and in aggressive/corrosive environments. A coating containing gadolinium-based composite materials can increase the alloy protection by strong electron transfer between the host alloy and the lanthanide-containing protective layer. This investigation aims to develop a Gd nanorod functionalised graphene oxide material as a corrosion inhibition barrier on the Mg alloy surface. The obtained functional materials were characterised by various spectroscopy techniques. The corrosion inhibition and composite material stability were studied by the electrochemical methods. The electrochemical stability was shown to increase with the applied current. The hydrogen evolution constantly increased and the corrosion inhibition significantly improved. Also, the computational studies of the material were performed, and their results support the experimental findings. Overall, the resultant composite material's corrosion resistance and cyclic stability are improved, and it could be used as a sodium-ion battery cathode material due to its high reversibility.

Hydrophilic Biocompatible Poly(Acrylic Acid-co-Maleic Acid) Polymer as a Surface-Coating Ligand of Ultrasmall Gd2O3 Nanoparticles to Obtain a High r1 Value and T1 MR Images

The water proton spin relaxivity, colloidal stability, and biocompatibility of nanoparticle-based magnetic resonance imaging (MRI) contrast agents depend on the surface-coating ligands. Here, poly(acrylic acid-co-maleic acid) (PAAMA) (Mw = ~3000 amu) is explored as a surface-coating ligand of ultrasmall gadolinium oxide (Gd2O3) nanoparticles. Owing to the numerous carboxylic groups in PAAMA, which allow its strong conjugation with the nanoparticle surfaces and the attraction of abundant water molecules to the nanoparticles, the synthesized PAAMA-coated ultrasmall Gd2O3 nanoparticles (davg = 1.8 nm and aavg = 9.0 nm) exhibit excellent colloidal stability, extremely low cellular toxicity, and a high longitudinal water proton spin relaxivity (r1) of 40.6 s-1mM-1 (r2/r1 = 1.56, where r2 = transverse water proton spin relaxivity), which is approximately 10 times higher than those of commercial molecular contrast agents. The effectiveness of PAAMA-coated ultrasmall Gd2O3 nanoparticles as a T1 MRI contrast agent is confirmed by the high positive contrast enhancements of the in vivo T1 MR images at the 3.0 T MR field.

Carbonate and phosphite encaged in frameworks constructed from square lanthanum aminopolycarboxylates and sodium chloride

Novel additives of lanthanum aminopolycarboxylates with inorganic anions, Na12n[La(edta)L]4n·8nNaCl·4nH2O (1: L = HPO32-; 2: L = CO32-) and K12n[La(cdta)(CO3)]4n·35nH2O (3) (H4edta = ethylenediaminetetraacetic acid; H4cdta = cyclohexanediaminetetraacetic acid), were obtained in alkaline solution. Structural analyses reveal that 1 and 2 are isomorphous and contain interesting square structures. HPO32- (CO32-) was encaged in the constructed tetranuclear frameworks. Tetranuclear lanthanum ethylenediaminetetraacetate was further encaged in superstructures of sodium chloride. 3 has a similar square structure, in which edta is replaced by cdta. All complexes are fully characterized via elemental, FT-IR, NMR, thermogravimetric and structural analyses. Solution 13C NMR spectra show that 1 and 2 dissociate into mononuclear units in water. Interestingly, 2 possesses 3.7 Å diameter holes inside its crystals, which can adsorb a small amount of O2 or CO2 selectively. The amounts of O2 and CO2 adsorbed increase gradually from 0.32 and 0.38 mg g-1 at 0.4 bar to 15.90 and 10.54 mg g-1 at 29.9 bar, respectively.

Structural and thermodynamic aspects of water–carbonate exchange equilibrium for MIII/IV–EDTA–carbonate systems

The carbonate anion readily displaces water molecules in the [Er(EDTA)(H₂O)₂]⁻ complex and though it is mainly an entropy driven process, the formation of the [Er(EDTA)(CO₃)]^3– complex is additionally enthalpy stabilized.

Stable and non-toxic ultrasmall gadolinium oxide nanoparticle colloids (coating material = polyacrylic acid) as high-performance T1 magnetic resonance imaging contrast agents

For use as positive (T₁) magnetic resonance imaging contrast agents (MRI-CAs), gadolinium oxide (Gd₂O₃) nanoparticle colloids (i.e. nanoparticles coated with hydrophilic ligands) should be stable, non-toxic, and ultrasmall in particle diameter for renal excretion. In addition, they should have a high longitudinal water proton relaxivity (r₁) and r₂/r₁ ratio that is close to one (r₂ = transverse water proton relaxivity) for high-performance. In this study, we report ultrasmall Gd₂O₃ nanoparticle colloids [coating material = polyacrylic acid, M_w = ∼5100 Da] satisfying these conditions. The particle diameter was monodisperse with an average value of 2.0 ± 0.1 nm. The colloidal suspension exhibited a high r₁ value of 31.0 ± 0.1 s⁻¹ mM⁻¹ and r₂/r₁ ratio of 1.2, where r₁ was ∼8 times higher than that of commercial Gd-chelates: the cooperative induction model was proposed to explain this. The effectiveness of the colloidal suspension as a high-performance T₁ MRI-CA was confirmed by taking in vivo T₁ MR images in a mouse after intravenous administration. Highly positive contrast enhancements were observed in various organs of the mouse such as the liver, kidneys, and bladder. The colloidal suspension was then excreted through the bladder.

Stable and non-toxic ultrasmall Gd₂O₃ nanoparticle colloids as high-performance T₁ MRI-CA were developed.

Interaction of Gd-DTPA with phosphate and phosphite: toward the reaction intermediate in nephrogenic systemic fibrosis

A commercially used gadolinium based contrast agent Gd-DTPA was substituted by phosphate and phosphite to form K₆[Gd₂(DTPA)₂(HPO₄)]·10H₂O and K₆[Gd₂(DTPA)₂(HPO₃)]·7H₂O respectively. Their analogous lanthanum complies are compared. These results are related to NSF formation.

Fluoride-specific fluorescence/MRI bimodal probe based on a gadolinium(iii)–flavone complex: synthesis, mechanism and bioimaging application in vivo

The present work reports a bimodal probe for the fluorescence and magnetic resonance detection of fluoride ion (F⁻) in aqueous medium andin vivo.

A water soluble calcium–sodium based coordination polymer: selective release of calcium at specific binding sites on proteins

A calcium–sodium based water soluble coordination complex, [{Ca₄Na(EGTA)₂(H₂O)₁₃}_n·NO₃] (EGTA = ethylene bis(oxyethylenenitrilo)tetraaceticacid), has been synthesized hydrothermally and characterized using spectroscopic and single crystal X-ray diffraction techniques.