Magnetic susceptibilities and knight shifts of the intermetallic compounds NdCu4 and NdCu5

The magnetic susceptibility and Knight shift of the intermetallic compounds NdCu₄ and NdCu₅ were investigated over the temperature range 80–850 K. The most important contributions to the magnetic susceptibility are the Curie-Weiss term, expressing the paramagnetism of the localized 4?-electrons, and a temperature independent term, both of which have been determined. The phenomenological quantity J_s? between the 4?-electron and conduction electron spins was found to be ?2.46.10^?3eV for NdCu₄ and 1.35.10^?3 eV for NdCu₅. A reversal in the sign of the s-? coupling for CeCu₅ was noted.     

X-ray diffraction and EXAFS studies of hydroxo-Cu(II) complexes based on a calix[6]arene-N3 ligand: evidence for a mononuclear-dinuclear equilibrium controlled by supramolecular features

The formation of hydroxo complexes based on a calix[6]trisimidazole ligand is described. Deprotonation of the mononuclear Cu(II)-aqua complex gives rise to a dinuclear bis(mu-hydroxo) complex that has been characterized by X-ray diffraction analysis. Spectroscopic studies (EPR and UV-vis), conducted in dichloromethane solutions in the presence of various coordinating cosolvents (DMF, EtOH, or RCN) or with acetamide, revealed the coexistence of a mononuclear hydroxo species. The latter could be trapped by acetic acid to provide an acetato-Cu(II) complex that presents close spectroscopic features. An EXAFS study first conducted on the hydroxo-Cu(II) complex led to an excellent fit for the dinuclear core. It then allowed for the characterization of the mononuclear acetato complex with an acetamide guest included in the calixarene cavity. Hence, this study illustrates the flexibility of calixarene-based ligands and the role of the second coordination sphere in the stabilization of acidic or basic Cu(II) complexes.     

Synthesis and glycosidase inhibitory activity of new penta-substituted C8-glycomimetics

The syntheses of new C8-carbasugars and -aminocyclitols related to miglitol and voglibose are described. The key step involves the ring closing metathesis of 1,9-dienes derived from d-mannitol. Chemical transformations of the newly created double bond of the resulting cyclooctenes involved notably hydroboration and reductive amination. The inhibitory activity of the glycomimetics so-obtained has been evaluated towards 24 commercially available glycosidases.     

Selective amperometric detection of dopamine using OPPy-modified diamond microsensor system

Highly boron-doped diamond microfiber electrodes (BDDMF) were fabricated and characterized by the use of Scanning Electron Microscopy (SEM), Raman spectroscopy, and cyclic voltammetry. Amperometric detection of dopamine (DA), a neurotransmitter was achieved at pH 7.0, using BDDMF electrodes. The interferences from ascorbic acid (AA) and DOPAC were efficiently eliminated by using overoxidized polypyrrole-modified BDDMF electrodes, which also increased the sensitivity for the detection of dopamine. The limit of detection (S/N = 3) for dopamine was 0.1 nM, which is one order lower than that observed for carbon microfiber electrodes (CMFE), and the linear dynamic range was obtained from 0.5 nM to 100 microM (r2 = 0.997). The amperometric response for 0.5 nM dopamine has shown high stability with an RSD of 5.4% (n = 5). Highly reproducible results were obtained with an RSD of 6.2% for 10 measurements of 1 nM DA taken during 10 h and also remained the same, during measurements for 7 days, with no variation in efficiency for rejection of AA and DOPAC.     

Detection of magnetic field effects by confocal microscopy

Certain pairs of paramagnetic species generated under conservation of total spin angular momentum are known to undergo magnetosensitive processes. Two prominent examples of systems exhibiting these so-called magnetic field effects (MFEs) are photogenerated radical pairs created from either singlet or triplet molecular precursors, and pairs of triplet states generated by singlet fission. Here, we showcase confocal microscopy as a powerful technique for the investigation of such phenomena. We first characterise the instrument by studying the field-sensitive chemistry of two systems in solution: radical pairs formed in a cryptochrome protein and the flavin mononucleotide/hen egg-white lysozyme model system. We then extend these studies to single crystals. Firstly, we report temporally and spatially resolved MFEs in flavin-doped lysozyme single crystals. Anisotropic magnetic field effects are then reported in tetracene single crystals. Finally, we discuss the future applications of confocal microscopy for the study of magnetosensitive processes with a particular focus on the cryptochrome-based chemical compass believed to lie at the heart of animal magnetoreception.

Confocal microscopy is showcased as a powerful technique for the measurement of spatiotemporally-resolved magnetic field effects in both solutions and single crystals.     

Detection of Heavy Metals in Water Using Graphene Oxide Quantum Dots: An Experimental and Theoretical Study

In this work, we investigate by ab initio calculations and optical experiments the sensitivity of graphene quantum dots in their use as devices to measure the presence, and concentration, of heavy metals in water. We demonstrate that the quenching or enhancement in the optical response (absorption, emission) depends on the metallic ion considered. In particular, two cases of opposite behaviour are considered in detail: Cd2+, where we observe an increase in the emission optical response for increasing concentration, and Pb2+ whose emission spectra, vice versa, are quenched along the concentration rise. The experimental trends reported comply nicely with the different hydration patterns suggested by the models that are also capable of reproducing the minor quenching/enhancing effects observed in other ions. We envisage that quantum dots of graphene may be routinely used as cheap detectors to measure the degree of poisoning ions in water.     

Removal of Cs,Sr, U and Pu species from simulated nuclear waste effluent using graphene oxide

This article reports the findings from a series of radioactive experimental trials which have examined the sorption properties of graphene oxide focused on four key radionuclides commonly linked to effluent challenges in the nuclear industry—Cs, Sr, U and Pu. Unlike previous experimental studies, simulated effluent waste solutions were utilised with compositions typical of those found at the Sellafield nuclear site, UK. Molecular dynamics simulations were performed in parallel to elucidate the functional groups to which radionuclides preferentially adsorb.     

Block copolymer‐directed synthesis of porous anatase for lithium‐ion battery electrodes

A templating method is developed to produce porous nanocrystalline anatase materials for negative electrodes in lithium‐ion batteries (LIBs). Amphiphilic diblock copolymers are used to generate template films with phase‐separated internal structure. Subsequent swelling with acidified titanium(IV) bis(ammonium lactato) dihydroxide (TALH) solution yielded structured hybrid films. Upon heating, the formation of TiO₂ nanocrystals is induced, resulting in a three‐dimensional mesoporous structure directed by the bulk morphology of the polymer template. In comparison to commercial nanosized anatase, the structured anatase shows significant performance improvements in lithium‐ion coin cell batteries in terms of capacity, stability, and rate capability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1890–1896     

Uptake and depletion of the antibiotic sulfadiazine 14C in rainbow trout (Oncorhynchus mykiss)

Journal of Radioanalytical and Nuclear Chemistry - Sulfadiazine is an antibiotic used in animals and humans, this molecule is being released increasingly into the aquatic environment, which is why...