Novel rhenium(I) catalysts for the isomerization of propargylic alcohols into α,β-unsaturated carbonyl compounds: an unprecedented recyclable catalytic system in ionic liquids

Carbonyl rhenium(I) complexes are efficient catalysts for the regioselective isomerization of terminal propargylic alcohols into α,β-unsaturated aldehydes or ketones which can be used as an unprecedented recyclable catalytic system (up to 10 consecutive runs) in the ionic liquid [BMIM][PF(6)].     

A simple, general route to 2-pyridylidene transition metal complexes

Pyridinium 2-carboxylates decompose thermally in the presence of a variety of late transition metal precursors to yield the corresponding 2-pyridylidene-like complexes. The mild reaction conditions and structural diversity that can be generated in the heterocyclic ring make this method an attractive alternative for the synthesis of 2-pyridylidene complexes. IR spectra of the Ir(i) carbonyl compounds [IrCl(NHC)(CO)(2)] indicate that these N-heterocyclic carbene ligands are among the strongest σ-electron donors.     

Bis[μ‐4‐(ethylammoniomethyl)‐3,5‐dimethylpyrazolato‐κ2N1:N2]bis[(η4‐1,5‐cyclooctadiene)rhodium(I)] dichloride dichloromethane methanol solvate

In the title compound, [Rh₂(C₈H₁₅N₃)₂(C₈H₁₂)₂]Cl₂·CH₂Cl₂·CH₃OH, the dinuclear Rh^I complex has C₂ symmetry and the two pyrazolato ligands act as μ‐bridges. The coordination of each Rh^I cation is completed by one cyclo­octa­diene (COD) ligand. It is shown that the average Rh—C(COD) distance is linearly dependent on the Rh—N(pyrazole) distance in this type of compound, and this is ascribed to the steric hindrance produced by the packing.     

Melnikov method for parabolic orbits

The present work completes the study of the conditions under which Melnikov method can be used when the unperturbed system has a parabolic periodic orbit with a homoclinic loop, by considering the case of orbits whose associated Poicaré map has linear part equal to the identity. The result is that the conditions for the persistence under perturbation of the invariant manifolds also ensure the convergence of the Melnikov integral and hence the applicability of the method.     

Luminescent Thermochromism of 2D Coordination Polymers Based on Copper(I) Halides with 4‐Hydroxythiophenol

Solvothermal reactions between copper(I) halides and 4‐mercaptophenol give rise to the formation of three coordination polymers with general formula [Cu₃X(HT)₂]_n (X=Cl, 1 ; Br, 2 ; and I, 3 ). The structures of these coordination polymers have been determined by X‐ray diffraction at both room‐ and low temperature (110 K), showing a general shortening in Cu?S, Cu?X and Cu?Cu bond lengths at low temperatures. 1 and 2 are isostructural, consisting of layers in which the halogen ligands act as μ₃‐bridges joining two Cu1 and one Cu2 atoms whereas in 3 the iodine ligands is as μ₄‐mode but the layers are quasi‐isostructural with 1 or 2 . These compounds show a reversible thermochromic luminescence, with strong orange emission for 1 and 2 , but weaker for 3 at room temperature, whereas upon cooling at 77 K 1 and 2 show stronger yellow emission, and 3 displays stronger green emission. DFT calculations have been used to rationalize these observations. These results suggest a high potential for this novel and promising stimuli‐responsive materials.     

Cava Wine Authentication Employing a Voltammetric Electronic Tongue

The application of an Electronic Tongue for the classification of cava samples based on their different ageing times is reported. As such, voltammetric responses were obtained from an array of six bulk‐modified graphite‐epoxy electrodes, which exhibited marked mix‐responses towards the different samples. Obtained responses were then preprocessed employing FFT and the resulting coefficients were input to a LDA model which allowed the classification of the samples according to its vintage time. Besides, a quantitative model employing ANNs was built for the prediction of the total amount of sugar present in the samples, a parameter also used to classify cava samples.