Bimetallic Gold(I) Complexes with Ethynyl‐Helicene and Bis‐Phosphole Ligands: Understanding the Role of Aurophilic Interactions in their Chiroptical Properties

Monometallic gold(I)‐alkynyl‐helicene complexes ( 1 a , b ) and bimetallic gold(I)‐alkynyl‐helicene architectures featuring the presence ( 2 a , b ) or absence ( 3 a , b ) of aurophilic intramolecular interactions were prepared by using different types of phosphole ligands (mono‐phosphole L1 or bis‐phospholes L2 , 3 ). The influence of the Au^I d¹⁰ metal center(s) on the electronic, photophysical, and chiroptical properties of these unprecedented phosphole‐gold(I)‐alkynyl‐helicene complexes was examined. Experimental and theoretical results highlight the importance of ligand‐to‐ligand‐type charge transfers and the strong effect of the presence or absence of Au^I–Au^I interactions in 2 a , b .     

An unusual approach to spirolactones and related structures

Spirocyclic structures can be obtained by an ipso-type radical cyclisation onto a furan or a suitably substituted pyrrole followed by oxidation of the stabilised radical adduct.     

A simple two steps ytterbium triflate‐catalysed preparation of 2,2‐dimethyl‐2h‐chromenes from salicylaldehydes and 2‐methylpropene

The preparation of various 2,2‐dimethyl‐2H‐chromenes was achieved in two steps via an ytterbium triflate‐catalysed reaction between salicylaldehydes, trimethylorthoformate and 2‐methylpropene. From salicylaldehyde, two reaction products were characterised: 4‐methoxy‐2,2‐dimethylchroman and 2‐(1,3‐dimethoxy‐3‐methylbutyl)phenol. The former compound probably results from a Lewis acid‐catalysed [2+4] cycloaddition between the intermediate quinonemethide and 2‐methylpropene whereas the latter may occur via a reaction related to a carbonyl‐ene reaction between the quinonemethide and 2‐methylpropene. Both compounds were subjected to a catalytic acidic treatment leading to 2,2‐dimethyl‐2H‐chromene. Starting from various salicylaldehydes, the scope of this method was investigated.     

1H-NMR Metabolomics as a Tool for Winemaking Monitoring

The chemical composition of wine is known to be influenced by multiple factors including some viticulture practices and winemaking processes. ¹H-NMR metabolomics has been successfully applied to the study of wine authenticity. In the present study, ¹H-NMR metabolomics in combination with multivariate analysis was applied to investigate the effects of grape maturity and enzyme and fining treatments on Cabernet Sauvignon wines. A total of forty wine metabolites were quantified. Three different stages of maturity were studied (under-maturity, maturity and over-maturity). Enzyme treatments were carried out using two pectolytic enzymes (E1 and E2). Finally, two proteinaceous fining treatments were compared (vegetable protein, fining F1; pea protein and PVPP, fining F2). The results show a clear difference between the three stages of maturity, with an impact on different classes of metabolites including amino acids, organic acids, sugars, phenolic compounds, alcohols and esters. A clear separation between enzymes E1 and E2 was observed. Both fining agents had a significant effect on metabolite concentrations. The results demonstrate that ¹H-NMR metabolomics provides a fast and robust approach to study the effect of winemaking processes on wine metabolites. These results support the interest to pursue the development of ¹H-NMR metabolomics to investigate the effects of winemaking on wine quality.     

Solid-phase synthesis of "mixed" peptidomimetics using Fmoc-protected aza-beta3-amino acids and alpha-amino acids

[structure: see text] A solid-phase fluorenylmethyloxycarbonyl (Fmoc)-based synthesis strategy is described for "mixed" aza-beta3-peptides as well as a convenient general approach for their required building blocks, the aza-beta3-amino acid residues (aza-beta3-aa). These monomers allow the synthesis of relatively large quantities of pure mixed aza-beta3-peptides. The required Fmoc-substituted aza-beta3-amino acids are accessible by convenient synthesis, and a number of monomers including those containing side chains with functional groups have been synthesized. The method was applied toward the solid-phase synthesis of aza-beta3-peptide mimetics of a biologically active histone H4 sequence.     

Direct Electron Transfer of Hemoglobin and Myoglobin at the Bare Glassy Carbon Electrode in an Aqueous BMI.BF4 Ionic‐Liquid Mixture

Direct and remarkably fast electron transfers between a bare glassy carbon electrode and heme proteins (hemoglobin or myoglobin) are obtained by using an aqueous 1‐butyl‐3‐methyl imidazolium tetrafluoroborate (BMI.BF₄) ionic‐liquid mixture as electrolyte. The ionic liquid is observed to play a key role in the achievement of the electron transfer. The experimental data show that the proteins are not strongly adsorbed onto the electrode surface while giving rise to sharp and well‐defined redox responses. Such a finding contrasts with most of the reported works found in literature and—beyond the fundamental aspect—it may be of interest in applications where adsorption is critical. Moreover, the electrocatalytic activity of the proteins toward the reduction of oxygen and nitrite in the aqueous BMI.BF₄ mixture is evidenced, showing the potential of this simple approach for bioelectroanalytical devices.     

Chiral recognition of amines and amino acid derivatives by optically active ruthenium Halterman porphyrins in organic solvents and water

The complexation of optically active or racemic amines, amino esters and amino acids with chiral ruthenium Halterman porphyrins is described. For various amino esters, chiral recognition was observed for the complexation of the ligand with up to 60% enantiomeric excess for 1-(1-naphthyl) ethylamine. A water-soluble ruthenium Halterman porphyrin, due to the presence of four sulfonate groups at the para-positions, was also prepared and used for the chiral recognition of amino acids in water.     

Synthesis of benzo[c][1,8]phenanthrolin‐6‐one through cyclization of N‐(isoquinol‐5‐yl)‐2‐bromo‐benzamide derivatives

In the course of our search for compounds with potential antitumor properties we have undertaken the synthesis of benzo[c][1,8]phenanthroline derivatives. Our project required the preparation of 8,9‐dimethoxy benzo[c][1,8]phenanthrolin‐6‐ones. This was first attempted by the lithiumdiisopropylamide cyclization of N‐(isoquinol‐5‐yl)‐2‐bromo‐4,5‐dimethoxybenzamide. The reaction led to 40% of the unexpected internal Diels‐Alder adduct 3,4‐dimethoxy‐6H‐pyrido[2,3‐i]6,8a‐ethenoindolo[cd]isoquinoline‐2(1H)‐one, which arose from a benzyne intermediate. In a second and more successful approach, the internal biaryl palladium diacetate‐assisted coupling reaction of properly N‐protected N‐(isoquinol‐5‐yl)‐2‐bromo‐4,5‐dimethoxybenzamide was studied. The optimisation of the protecting group necessary for this procedure led to a 64% yield of the target compound starting from N,N‐(isoquinol‐5‐yl)‐bis‐(2‐bromo‐4,5‐dimethoxybenzamide).     

Traceability of absorbed dose in photon radiation therapy: from primary standard to patient treatment

The relevant standard quantity for radiation therapy is the absorbed dose to water. This quantity refers to the amount of energy locally absorbed in a small volume of water divided by the mass of this volume. The aim of this paper is to present a short overview on the establishment of traceability to national standards of absorbed doses delivered to patients in radiation therapy. The approach used at LNE-LNHB, the French national metrology laboratory for ionizing radiation, to determine the reference value of absorbed dose to water is presented and the chain of traceability from the reference value to the treatment of the patient is described.     

Effect of partially methylated β cyclodextrin on percutaneous absorption of metopimazine

Metopimazine (MPZ) is an antiemetic drug used by oral and rectal administration. A transdermal delivery system of MPZ may present a great advantage for the treatment of nausea and vomiting to improve therapeutic adhesion. MPZ is a lipophilic drug with poor water solubility. Partially methyled β cyclodextrin (PMβ-CD) was tested to enhance percutaneous absorption of MPZ. Complex MPZ/cyclodextrin was characterized by Higushi’s phase solubility, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analyses and MPZ octanol partition coefficient was also determinated. The permeation of free MPZ and inclusion complex through pig skin were investigated using Franz’s cells. Four concentrations of cyclodextrins, 0, 5, 10 and 20% were tested. Partition coefficient was depending on pH of the solution. At pH 5.5, MPZ ionization increased the hydrophily (0.71) and at pH 10.3, non-ionized MPZ was the dominant form (591). The solubility of MPZ increased with the concentration of PMβ-CD and the phase solubility diagram is an Ap type. The used characterization analyses demonstrated the formation of an inclusion complex and this complex improved percutaneous absorption of MPZ. No MPZ flux was detected for a suspension of MPZ and it was more important with MPZ hydrochloride, 0.177 ± 0.044 μg/h/cm2. Flux was increased to 0.570 ± 0.058 μg/h/cm2 with a concentration of 20%. The use of cyclodextrin with MPZ hydrochloride increased also the percutaneous absorption with 0.549 ± 0.175 μg/h/cm2 for a concentration of 5%, 0.435 ± 0.031 μg/h/cm2 for a concentration of 10% and 0.474 ± 0.054 μg/h/cm2 for a concentration of 20%. This study shows that PMβ-CD improves percutaneous penetration of MPZ. But the absorption is not enough to allow a therapeutic effect. Cyclodextrin complex increases MPZ solubility and this bioavailability at the skin surface, and cyclodextrin may also modify the barrier propriety of skin.