The first total syntheses of (±)-Preussomerins K and L using 2-arylacetal anion technology

The first syntheses of newly isolated members of the Preussomerin family, Preussomerins K and L, are reported. Key steps include the functionalisation of a 2-arylacetal anion, one-pot Friedel-Crafts cyclisation-deprotection and reductive opening of epoxides.     

Materials for spintronic: Room temperature ferromagnetism in Zn–Mn–O interfaces

In this paper we study the room temperature ferromagnetism reported on Mn-doped ZnO and ascribed to spin polarization of conduction electrons. We experimentally show that the ferromagnetic behaviour is associated to the coexistence of Mn³⁺ and Mn⁺⁴ in MnO₂ grains where diffusion of Zn promotes the Mn⁴⁺→Mn³⁺ reduction. Potential uses of this material in spintronic devices are analysed.     

Structure of hydroxycinnamic acid derivatives established by high-perfomance liquid chromatography with photodiode-array detection

Summary The present paper describes the development of a method for the differentiation of hydroxycinnamic acid derivatives by HPLC with photodiode-array detection. Furthermore spectral data of the compounds under investigation are given. Whereas p-coumaric acid derivatives are distinguishable from caffeic and ferulic acid derivatives by the positions of their spectrum maxima and their convexity interval value, it is not possible to distinguish between caffeic and ferulic acid derivatives because of overlapping spectrum maxima and convexity interval values.     

Solvent-induced supramolecular isomerism in [Pt(S=C(NH2)2)4]2+ croconate salts

The role of solvent (and other species) in the formation of networks from tetrakis(thiourea)platinum(II) cations and croconate anions is examined, with crystallisations from DMSO giving rise to a structure containing solvent filled channels.     

Effect of growth conditions on the rheological properties and chemical composition ofVolcaniella eurihalina exopolysaccharide

The exopolysaccharide produced byVolcaniella eurihalina, an halophilic eubacterium, under different environmental and nutritional conditions, is studied.V. eurihalina synthesizes an acidic heteropolysaccharide, composed by rhamnose, glucose, and mannose, as well as amino sugars, uronic acids, and acetyl and sulphate residues. This composition varies depending on the nutrients of culture medium. Viscosity and pseudoplasticity of the polymer solutions are also influenced by the nutritional conditions in which the microorganism was grown.     

Method for detection of single-base mismatches using bimolecular beacons

This paper describes a method for the detection of single-base mismatches using DNA microarrays in a format that does not require labeling of the sample ("target") DNA. The method is based on disrupting fluorescence energy transfer (FRET) between a fluorophore attached to an immobilized DNA strand ("probe") and a quencher-containing sequence that is complementary except for an artificial mismatch (e.g. 5-nitroindole, 3-nitropyrole, or abasic site) at the site of interrogation. As the displacement of the FRET acceptor and hybridization of the unlabeled probe are bimolecular, the term "bimolecular beacons" is used to describe this approach. The analysis of a mismatch was based on differences in the amount of disruption in FRET upon hybridization of perfectly matched DNA targets and those containing single-base mismatches. Using this method and an oligonucleotide model system, A/C single-base mismatches were successfully discriminated at levels greater than that observed using surface-immobilized molecular beacons. The amount of discrimination was dependent on the identity of the artificial mismatch; greater discrimination was observed with 5-nitroindole (a "universal" base) than with an abasic site. G/T mismatches, considered to be particularly difficult to detect, were also successfully discriminated when quencher sequences containing 5-nitroindole were used.     

N,N′‐Di­thio­bisphthal­imide–nitro­benzene (2/1): a Pn solvate with localized solvent mol­ecules ordered head‐to‐tail in channels

N,N′‐Di­thio­bisphthal­imide crystallizes from nitro­benzene solution as a solvate, 2C₁₆H₈N₂O₄S₂·C₆H₅NO₂, having space group Pn. The bisphthal­imide mol­ecules are linked by C—H?O hydrogen bonds and by aromatic π–π‐stacking interactions, forming a framework enclosing continuous channels running along the [100] direction and accounting for ca 20% of the unit‐cell volume. The nitro­benzene mol­ecules lie in these channels, ordered in a head‐to‐tail fashion and linked to the bis­phthal­imide framework by C—H?O and C—H?π(arene) hydrogen bonds.     

Hydrogen bonding in 2‐amino‐4,6‐dimethoxypyrimidine, 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine and 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine: chains of fused rings and a centrosymmetric dimer

Molecules of 2‐amino‐4,6‐di­methoxy­pyrimidine, C₆H₉N₃O₂, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐­benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C₂₅H₂₃N₃O₂, (II), the mol­ecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)­pyrimidine, C₁₂H₁₉N₅, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I).     

pH‐Dependent Chloride Transport by Pseudopeptidic Cages for the Selective Killing of Cancer Cells in Acidic Microenvironments

Acidic microenvironments in solid tumors are a hallmark of cancer. Inspired by that, we designed a family of pseudopeptidic cage‐like anionophores displaying pH‐dependent activity. When protonated, they efficiently bind chloride anions. They also transport chloride through lipid bilayers, with their anionophoric properties improving at acidic pH, suggesting an H⁺/Cl^? symport mechanism. NMR studies in DPC micelles demonstrate that the cages bind chloride within the lipid phase. The chloride affinity and the chloride‐exchange rate with the aqueous bulk solution are improved when the pH is lowered. This increases cytotoxicity towards lung adenocarcinoma cells at the pH of the microenvironment of a solid tumor. These properties depend on the nature of the amino‐acid side chains of the cages, which modulate their lipophilicity and interactions with the cell membrane. This paves the way towards using pH as a parameter to control the selectivity of cytotoxic ionophores as anticancer drugs.     

Mathematics: a means of collaboration between industry and university

This paper is divided into two distinct but connected parts. In the first one we look for the best approach to the Mathematics teaching of the future engineer. This approach should have an eminently pragmatic character and should be directed towards teaching engineers to know and manage Mathematics at a tool. In the second part we illustrate how a collaboration with industry can be obtained from this kind of teaching.

Finally the conditions and consequences which should produce this cooperation are analysed, and some particular examples are mentioned.