Synthesis of homoconjugated oligomers derived from 7,7-diphenylnorbornane

A methodology for the synthesis of monodisperse homoconjugated oligomers (dimer, trimer, and tetramer) derived from cofacial 7,7-diphenylnorbornane (DPN) is described. Extended aromatic homoconjugation is observed in these oligomers as revealed by the electronic spectra. The effective homoconjugation length (EHL) is in the range of 4-5 DPN subunits.     

Cell-Free Supernatants Obtained from Fermentation of Cheese Whey Hydrolyzates and Phenylpyruvic Acid by Lactobacillus plantarum as a Source of Antimicrobial Compounds, Bacteriocins, and Natural Aromas

Cheese whey hydrolyzates supplemented with phenylpyruvic acid (PPA) and commercial nutrients can be efficiently metabolized by Lactobacillus plantarum CECT-221 to biosynthesize some compounds with attractive applications in the food market. The main metabolites of cell-free extracts were antimicrobial compounds such as phenyllactic acid (PLA) and lactic acid (LA). The production of PLA by L. plantarum CECT-221 was evaluated in the Man–Rogosa–Sharpe broth supplemented with two biosynthetic precursors: phenylalanine or PPA. Using 30.5 mM PPA, the microorganism increased sevenfold the concentration of PLA producing 16.4 mM PLA in 46 h. A concentration of 40 mM PPA was a threshold to avoid substrate inhibition. The biosynthesis of whey hydrolyzates as a carbon source was enhanced by fed-batch fermentation of PPA; the average productivity of PLA increased up to 45.4?±?3.02 mM after 120 h with a product yield of 0.244 mM mM^?1; meanwhile, LA reached 26.1?±?1.3 g L^?1 with a product yield of 0.72 g g^?1. Cell-free fed-batch extracts charged in wells showed bacteriocin activity with halos of 7.49?±?1.44 mm in plates inoculated with Carnobacterium piscicola and antimicrobial activity against Staphylococcus aureus (11.54?±?1.14 mm), Pseudomonas aeruginosa (10.17?±?2.46 mm), Listeria monocytogenes (7.75?±?1.31 mm), and Salmonella enterica (3.60?±?1.52 mm). Additionally, the analysis of the volatile composition of the headspace of this cell-free extract revealed that L. plantarum is a potential producer for natural aromas, such as acetophenone, with high price in the market. This is the first report of PLA production from cheese whey and PPA. The extracts showed bacteriocin activity and potential to be applied as an antimicrobial in the elaboration of safer foods.     

New Promises and Opportunities in 3D Printable Inks Based on Coordination Compounds for the Creation of Objects with Multiple Applications

This review focuses on the usefulness of coordination bonds to create 3D printable inks and shows how the union of chemistry and 3D technology contributes to new scientific advances, by allowing amorphous or polycrystalline solids to be transformed into objects with the desired shape for successful applications. The review clearly shows how there has been considerable increase in the manufacture of objects based on the combination of organic matrices and coordination compounds. These coordination compounds are usually homogeneously dispersed within the matrix, anchored onto a proper support or coating the printed object, without destroying their unique properties. Advances are so rapid that today it is already possible to 3D print objects made exclusively from coordination compounds without additives. The new printable inks are made mainly with nanoscale nonporous coordination polymers, metal–organic gels, or metal–organic frameworks. The highly dynamic coordination bond allows the creation of objects, which respond to stimuli, that can act as sensors and be used for drug delivery. In addition, the combination of metal–organic frameworks with 3D printing allows the adsorption or selective capacity of the object to be increased, relative to that of the original compound, which is useful in energy storage, gas separation, or water pollutant elimination. Furthermore, the presence of the metal ion can give them new properties, such as luminescence, that are useful for application in sensors or anticounterfeiting. Technological advances, the combination of various printing techniques, and the properties of coordination bonds lead to the creation of surprising, new, printable inks and objects with highly complex shapes that will close the gap between academia and industry for research into coordination compounds.     

An a priori error analysis of a type III thermoelastic problem with two porosities

In this work, we study, from the numerical point of view, a type III thermoelastic model with double porosity. The thermomechanical problem is written as a linear system composed of hyperbolic partial differential equations for the displacements and the two porosities, and a parabolic partial differential equation for the thermal displacement. An existence and uniqueness result is recalled. Then, we perform its a priori error numerical analysis approximating the resulting variational problem by using the finite element method and the implicit Euler scheme. The linear convergence of the algorithm is derived under suitable additional regularity conditions. Finally, some numerical simulations are shown to demonstrate the accuracy of the approximations and the dependence of the solution on a coupling coefficient.     

Synthesis of chiral 2-furyl and 3-nitro-7-oxabicyclo[2.2.1]heptane derivatives from sugars

Asymmetric Diels–Alder reactions between 2-methylfuran and chiral (E)-1,2-dideoxy-1-nitroalkenes derived from d-mannose and d-galactose were carried out at room temperature, under 13 kbar pressure. The processes were completely regioselective, and only the four adducts with penta-O-acetyl-1′-C-(4-methyl-3-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-yl)pentitols structures were formed in each case. These adducts, as well as those arising from cycloadditions of the same nitroalkenes and furan, have been converted into chiral derivatives, such as 2-furyl substituted 1-nitrosugars, 2-glyco-4-methyl-3-nitro-7-oxabicyclo[2.2.1]heptanes, and 5,6-exo-epoxy-2-glyco-3-nitro-7-oxabicyclo[2.2.1]hept-5-enes.     

The extraction of environmentally polluting cations from aqueous media with novel polyamides containing cation‐ and anion‐selective host units

This work describes the synthesis and characterization of polyamides, copolyamides, and polyamide blends containing cation‐ and anion‐selective host units in the pendant structure and their application to the extraction of environmentally polluting cations from aqueous media. The cation host unit consists of a crown ether subunit and the anion receptor is a urea group. The preparation of the copolymers involves the copolymerization of two isophthalic acid derivatives—one containing a lateral urea group and the other a crown ether moiety—with m‐phenylenediamine. The molar ratio of crown ether to urea subunits is varied from 1/1 to 1/2 and 1/3 to fit the ion and counterion ratio of metals with valences I, II, and III. The extraction effectiveness and selectivity is related to the composition of the copolymer or the polymer blend, and thus formally to the cation to anion host units ratio, which therefore permits the á la carte design of materials to be used in the decontamination and elimination of polluting cations. With regard to the cation extraction from aqueous media with polyamide solid phases, the polymer structure design leads to the extraction of high percentages of Hg^II (almost 100%) and moderate extraction of Pb^II and Cr^III. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 670–681, 2009     

Ferromagnetism in dinuclear copper(II)-phenolate complexes with exogenous O-donor bridges: a comparative study

The copper(II) complex Cu2L(OAc)(H2O)3.5, 1 x 3.5H2O was obtained and its reactivity in a basic medium investigated. Complex 1 x 3.5H2O shows different reaction patterns in air and in an inert atmosphere. Accordingly, interaction of 1 x 3.5H2O with Me4NOH x 5H2O in methanol-acetonitrile in air yields the hydroxide complex Cu2L(OH)(H2O)1.125, 2 x 1.125H2O while Cu2L(OMe)(MeOH)0.5(H2O), 3 x 0.5MeOH x H2O is isolated under an argon atmosphere. The products 1-3 were fully characterised and single crystals of {[Cu2L(OAc)] x MeCN x 3.5H2O}2, 1 x MeCN x 3.5H2O, {[Cu2L(OH)] x MeCN x 1.125H2O}2, 2 x MeCN x 1.125H2O and [Cu2L(OMe)] x 0.5MeOH x H2O, 3 x 0.5MeOH x H2O solved. The single X-ray study shows that 1-3 are dinuclear complexes with an endogenous phenol oxygen and an exogenous O-bridge. Magnetic characterisation of the three dinuclear complexes was performed, showing an apparent anomalous intramolecular ferromagnetic coupling between the metal atoms in all cases.     

Selective Michael-aldol reaction by use of sterically hindered aluminum aryloxides as Lewis acids: an easy approach to cyclobutane amino acids

A formal [2 + 2] cycloaddition of 2-amidoacrylates with monosubstituted donor olefins, including its asymmetric version, is described. The stereoselectivity of this reaction can be modulated by the use of sterically hindered aluminum aryloxides or methylaluminoxane as Lewis acids. The reaction was applied to the synthesis of both stereoisomers of 2-benzyloxycyclobutane-alpha-amino acid, which are protected serine analogues c(4)Ser(OBn).     

Rhodium‐Catalyzed Annulation of ortho‐Alkenyl Anilides with Alkynes: Formation of Unexpected Naphthalene Adducts

o‐Alkenyl N‐triflylanilides underwent rhodium(III)‐catalyzed oxidative annulations with alkynes to produce different types of naphthylamides in a process which involves the cleavage of two C?H bonds. Remarkably, besides formal dehydrogenative (4C+2C) cycloadducts, the reaction also produces variable amounts of isomeric naphthylamides, whose formation requires a formal migration of the alkenyl moiety from the ortho to the meta position of the anilide. The annulation reaction can be efficiently carried out in the absence of external oxidants, such as Cu(OAc)₂.