Intermediate coupling model description of55Fe and57Fe

The properties of the negative parity states of⁵⁵Fe and⁵⁷Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states.     

A mechanophysical phase transition provides a dramatic example of colour polymorphism: the tribochromism of a substituted tri(methylene)tetrahydrofuran-2-one

Background

Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed “tribochromism”. We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies.

Results

A number of 5-dicyanomethylene-4-diphenylmethylene-3-disubstitutedmethylene-tetrahydrofuran-2-one compounds have been prepared and structurally characterised. The compounds are obtained as yellow or dark red crystals, or, in one case, both. In two cases where yellow crystals were obtained, we found that crushing the crystals gave a deep red powder. Structure determinations, including those of the one compound which gave both coloured forms, depending on crystallisation conditions, showed that the yellow crystals contained molecules in which the structure comprised a folded conformation at the diphenylmethylene site, whilst the red crystals contained molecules in a twisted conformation at this site. Lattice energy and molecular conformation energies were calculated for all molecules, and showed that the conformational energy of the molecule in structure IIIa (yellow) is marginally higher, and the conformation thus less stable, than that of the molecule in structure IIIb (red). However, the van der Waals energy for crystal structure IIIa, is slightly stronger than that of structure IIIb – which may be viewed as a hint of a metastable packing preference for IIIa, overcome by the contribution of a more stabilising Coulomb energy to the overall more favourable lattice energy of structure IIIb.

Conclusions

Our studies have shown that the crystal colour is correlated with one of two molecular conformations which are different in energy, but that the less stable conformation can be stabilised by its host crystal lattice.

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Graphical abstract Graphical representation of the structural and colour change in the tribochromic compound (III).

     

Model‐Based Nanoengineered Pharmacokinetics of Iron‐Doped Copper Oxide for Nanomedical Applications

The progress in nanomedicine (NM) using nanoparticles (NPs) is mainly based on drug carriers for the delivery of classical chemotherapeutics. As low NM delivery rates limit therapeutic efficacy, an entirely different approach was investigated. A homologous series of engineered CuO NPs was designed for dual purposes (carrier and drug) with a direct chemical composition–biological functionality relationship. Model‐based dissolution kinetics of CuO NPs in the cellular interior at post‐exposure conditions were controlled through Fe‐doping for intra/extra cellular Cu²⁺ and biological outcome. Through controlled ion release and reactions taking place in the cellular interior, tumors could be treated selectively, in vitro and in vivo. Locally administered NPs enabled tumor cells apoptosis and stimulated systemic anti‐cancer immune responses. We clearly show therapeutic effects without tumor cells relapse post‐treatment with 6 % Fe‐doped CuO NPs combined with myeloid‐derived suppressor cell silencing.     

New Photosensitizers Based on Heteroleptic CuI Complexes and CO2 Photocatalytic Reduction with [NiII(cyclam)]Cl2

Earth-abundant metal complexes have been attracting increasing attention in the field of photo(redox)catalysis. In this work, the synthesis and full characterisation of four new heteroleptic Cu^I complexes are reported, which can work as photosensitizers. The complexes bear a bulky diphosphine (DPEPhos=bis[(2-diphenylphosphino)phenyl] ether) and a diimine chelating ligand based on 1-benzyl-4-(quinol-2′yl)-1,2,3-triazole. Their absorption has a relative maximum in the visible-light region, up to 450 nm. Thus, their use in photocatalytic systems for the reduction of CO₂ with blue light in combination with the known catalyst [Ni^II(cyclam)]Cl₂ was tested. This system produced CO as the main product through visible light (λ=420 nm) with a TON up to 8 after 4 hours. This value is in line with other photocatalytic systems using the same catalyst. Nevertheless, this system is entirely noble-metal free.     

Four-electron reduction of dinitrogen during solution disproportionation of the organodimetallic (eta-C5Me4R)2Ta2(mu-Cl)4(R = Me, Et) to a new mu-eta1,eta1-N2 complex and odd-electron organotrimetallic cluster

(C5Me5R)2Ta2Cl4 (d2-d2) disproportionates under dinitrogen to [(C5Me4R)TaCl2]2(mu-N2) and the D3h cluster cation (C5Me4R)3Ta3(mu-Cl)6+ with anionic (C5Me4R)TaCl4-.     

Regularizing properties and propagations of singularities for thermoelastic plates

We consider the thermoelastic plate system, u_tt−γΔu_tt+Δ²u+αΔθ=0 , θ_t−κΔθ−αΔu_t=0 and we make a comparison between the models in which γ=0 and γ>0. We conclude that in the first case the plate system is of a parabolic type, while when γ>0 the corresponding system has a hyperbolic behaviour. © 1998 B. G. Teubner Stuttgart—John Wiley & Sons, Ltd.     

Thermal Stability of Ni-Fe/Co/Au/Co GMR Pseudo-Spin-Valves

Pseudo-spin-valves (PSV) structures, Ni₈₃Fe₁₇-3 nm / Co-2.5 nm / Au-t _Au / Co-2.5 nm, with 2.4t _Au3.2 nm were deposited by UHV magnetron sputtering. The weak ferromagnetic coupling J2×10^-6 J/m² between Ni-Fe/Co and Co layers and GMR effect 3% was found at RT. The GMR amplitude decreases monotonically from 5% at -100°C to 1% at 200°C. However, the slope of R(H) curve, i.e., GMR field sensitivity, is equal to about 1.5%/Oe and remains almost constant in the entire investigated temperature range. Additionally, our PSV display a good thermal stability, with no significant changes of magnetic and transport properties after annealing up to 250°C.     

Properties of irradiated PVC plasticized with non-endocrine disruptor

Polyvinylchloride (PVC) is under heavy attack from environmentalist groups due to the use of plasticizers and its recycling difficulties. Chloro-organics and phtalates are considered now as ubiquitous global contaminants due to their potential as weak endocrine disruptor and huge consumption. In order to make PVC acceptable for the irradiation processing industry in the long term, non-toxic plasticizers should be used. PVC was added with dioctyl phtalate (DOP) and epoxy soybean oil (ESO) and irradiated up to 50 kGy. Mechanical properties, optical properties and viscosity were measured and compared. The elongation and mechanical strength were under the usual range and they didn’t show any significant change in the studied range of irradiation dose. All the samples showed a weak yellowing effect after irradiation and the molecular weight measured by viscosimetry showed only negligible changes. In conclusion, DOP and ESO were shown to be effective in stabilizing the radiolytic abstraction of HCl from PVC. Both plasticizers imparted good color stability and overall properties to the products.