Highly efficient rhenium-catalyzed deoxygenation of sulfoxides without adding any reducing agent

This work reports a novel method for the deoxygenation of aromatic and aliphatic sulfoxides catalyzed by oxo-rhenium complexes without adding any reducing agent. The oxo-rhenium complex ReOCl₃(PPh₃)₂ proved to be very efficient for the deoxygenation of several sulfoxides with tolerance of different functional groups.     

Novel goniofufurone and 7-epi-goniofufurone mimics from an unexpected titanium-mediated displacement process

Treatment of 7-O-benzoyl-5-O-benzyl derivatives of (+)-goniofufurone or 7-epi-(+)-goniofufurone with titanium(IV) chloride or titanium(IV) bromide gave 7-chloro and 7-bromo-7-deoxy-goniofufurone mimics as the main reaction products along with minor amounts of the corresponding C-7 epimers. An unexpected cyclized product, benzoxepane 8 was isolated in some cases.     

Predicting optimal conditions to minimize quality deterioration while maximizing safety and functional properties of irradiated egg

Irradiation is an excellent method for improving the safety and functional properties of egg. However, the internal quality of egg can be deteriorated due to a rapid decrease in Haugh units. In this study, the optimal conditions for maintaining the quality and maximizing the safety and functional properties of egg were determined when combination of irradiation and chitosan coating was treated using response surface methodology (RSM). Independent degradation parameters—irradiation dose (0–2 kGy) and concentration of chitosan coating (0–2%) were assigned (?2,–1, 0, 1, 2), and 10 intervals were set on the basis of central composite design for the degradation experiment. The dependant variables within a confidence level less than 5% were Haugh units, foaming ability, foam stability, and number of Salmonella typhimurium. The predicted maximum values of Haugh units and foaming ability were 82.7 (irradiation dose 0.0006 kGy and concentration of chitosan solution 1.03%) and 62.2 mm (1.99 kGy and 0.86%), respectively. S. typhimurium inoculated on the egg surface was not detected after 1.86 kGy and 0.48%. Based on superimposing four-dimensional RSM with respect to freshness (Haugh units), functional property (foaming capacity and foam stability), and reduction of S. typhimurium, the predicted optimum ranges for irradiation dose and chitosan solution concentration were 0.35–0.65 kGy and 0.25–0.85%, respectively. The predicted optimum values were obtained from 0.45 kGy and 0.525%. This methodology can be used to predict egg quality and safety when different combination treatments were applied.     

Synergistic effect of ionizing radiation on chemical disinfectant treatments for reduction of natural microflora on seafood

The purpose of this study was to determine whether combined treatments would produce synergistic disinfection effects on seafood products such as mussel and squid compared with single treatments. We investigated the bactericidal effects of chlorine and ionizing radiation on the natural microflora of mussel and squid. Total aerobic bacteria initially ranged from 10² to 10⁴ Log CFU/g. More than 100 ppm of chlorine and irradiation at 1 kGy were sufficient to reduce the total aerobic bacteria on mussel and squid to a level lower than detection limit (10 CFU/g). Synergistic effects against natural microflora were observed for all combined treatment. These results suggest that a significant synergistic benefit results from combine chlorine-ionizing radiation treatment against natural microflora on mussel and squid.     

Gamma radiation effects on physical properties of parchment documents: Assessment of Dmax

Parchments are important documents that give testimony for History; therefore these materials should be respected and preserved. Considering incremental biodeterioration problems that have to be faced daily, the Archive of the University of Coimbra (AUC) is involved in different scientific projects in order to evaluate and determine new methods for document decontamination and preservation.The aim of this study was to evaluate gamma radiation effects on the colour and texture of the AUC parchment documents. The assessment of these effects was used to estimate the maximum gamma radiation dose (D_max) that could guarantee parchment documents′ decontamination treatment, without significant alteration of their physical properties. Parchment samples were exposed to gamma radiation doses ranging from 10 to 30 kGy. The texture and colour of samples were assessed before and after the irradiation procedure, using a texture analyser and an electronic colorimeter. Hardness and springiness were determined based on texture spectra. Lightness (L?), Chroma (C), greenness vs. redness (a*) and yellowness vs. blueness (b*) values were obtained from colorimetric measures. Results indicate no significant effects of gamma radiation on the texture and colour of parchment for the studied doses.     

Absolute configuration of strictosidinic acid

The absolute configuration of strictosidinic acid, (2S,3R,4S)‐3‐ethenyl‐2‐(β‐d ‐glucopyranosyloxy)‐4‐{[(1S)‐2,3,4,9‐tetrahydro‐1H‐pyrido[3,4‐b]indol‐1‐yl]methyl}‐3,4‐dihydro‐2H‐pyran‐5‐carboxylate, was determined from its sodium chloride trihydrate, poly[[diaqua((2S,3R,4S)‐3‐ethenyl‐2‐(β‐d ‐glucopyranosyloxy)‐4‐{[(1S)‐2,3,4,9‐tetrahydro‐1H‐pyrido[3,4‐b]indol‐2‐ium‐1‐yl]methyl}‐3,4‐dihydro‐2H‐pyran‐5‐carboxylate)sodium] chloride monohydrate], {[Na(C₂₆H₃₂N₂O₉)(H₂O)₂]Cl·H₂O}_n. The strictosidinic acid molecule participates in intermolecular hydrogen bonds of the O—H...O and O—H...Cl types. The solid‐state conformation was observed as a zwitterion, based on a charged pyridine N atom and a carboxylate group, the latter mediating the packing through coordination with the sodium cation.     

The Stereochemistry of 1,2,3‐Triols Revealed by 1H NMR Spectroscopy: Principles and Applications

The conformational compositions of the tris(α‐methoxy‐α‐phenylacetic acid) ester derivatives of 1,2,3‐prim,sec,sec‐triols are presented. These conformations have been determined by theoretical and experimental data (i.e., energy‐ and chemical‐shift calculations, circular dichroism (CD) experiments, coupling‐constant analysis, enantioselective deuteration experiments, and low‐temperature NMR spectroscopic studies). A detailed analysis of the anisotropic effects due to the most significant conformers in the ¹H NMR spectra supported the correlation between the ¹H NMR spectra (Δδ^RS value of H(3′) and |Δ(Δδ^RS)| parameters) and the absolute configuration of the substrate. The study also allows the identification of the pro‐R and pro‐S methylene protons from their vicinal coupling constants and relative chemical shifts.     

Designed Topology and Site‐Selective Metal Composition in Tetranuclear [MM′⋅⋅⋅M′M] Linear Complexes

The ligand 1,3‐bis[3‐oxo‐3‐(2‐hydroxyphenyl)propionyl]benzene (H₄L), designed to align transition metals into tetranuclear linear molecules, reacts with M^II salts (M=Ni, Co, Cu) to yield complexes with the expected [MM???MM] topology. The novel complexes [Co₄L₂(py)₆] ( 2 ; py=pyridine) and [Na(py)₂][Cu₄L₂(py)₄](ClO₄) ( 3 ) have been crystallographically characterised. The metal sites in complexes 2 and 3 , together with previously characterised [Ni₄L₂(py)₆] ( 1 ), favour different coordination geometries. These have been exploited for the deliberate synthesis of the heterometallic complex [Cu₂Ni₂L₂(py)₆] ( 4 ). Complexes 1 , 2 , 3 and 4 exhibit antiferromagnetic interactions between pairs of metals within each cluster, leading to S=0 spin ground states, except for the latter cluster, which features two quasi‐independent S=1/2 moieties within the molecule. Complex 4 gathers the structural and physical conditions, thus allowing it to be considered as prototype of a two‐qbit quantum gate.