A Switch in the Hydrophobic/Hydrophilic Gas-Adsorption Character of Prussian Blue Analogues: An Affinity Control for Smart Gas Sorption

Porous coordination polymers are molecule-based materials presenting a high degree of tunability, which offer many advantages for targeted applications over conventional inorganic materials. This work demonstrates that the hydrophilic/hydrophobic character of Prussian blue analogues having a lipophilic feature may be tuned to optimize the gas adsorption properties. The role of the coordinatively unsaturated metal sites is emphasized through a combination of theoretical and experimental study of water, ethanol, and n-hexane adsorption.     

On operators and search space topology in multi-objective flow shop scheduling

Multi-objective optimization using evolutionary algorithms identifies Pareto-optimal alternatives or their close approximation by means of a sequence of successive local improvement moves. While several successful applications to combinatorial optimization problems are known, studies of underlying problem structures are still scarce.     

Dynamic percolation in water in oil microemulsions revisited

Microemulsions (dispersions of water droplets, typical radius about 10 nm, in oil) show a particular percolation pattern, a so-called dynamical percolation. Predictions of scaling theory and Monte Carlo simulations were compared with experimental static and frequency dependent conductivity data. The latter gives evidence of two different time scales of charge transport.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday     

Formation of spanning water networks on protein surfaces via 2D percolation transition

The formation of spanning hydrogen-bonded water networks on protein surfaces by a percolation transition is closely connected with the onset of their biological activity. To analyze the structure of the hydration water at this important threshold, we performed the first computer simulation study of the percolation transition of water in a model protein powder and on the surface of a single protein molecule. The formation of an infinite water network in the protein powder occurs as a 2D percolation transition at a critical hydration level, which is close to the values observed experimentally. The formation of a spanning 2D water network on a single rigid protein molecule can be described by adapting the cluster analysis of conventional percolation studies to the characterization of the connectivity of the hydration water on the surface of finite objects. Strong fluctuations of the surface water network are observed close to the percolation threshold. Our simulations also furnish a microscopic picture for understanding the specific values of the experimentally observed hydration levels, where different steps of increasing mobility in the hydrated powder are observed.     

Reactions of Cyanomethanesulfonamides with Aldehydes and Synthesis of 2-Benzyl-2,3-dihydrobenzopyrano[3,2-e] [1,2,4]thiadiazine 1,1-Dioxides

Summary.  Reactions of cyanomethanesulfonamides with aromatic aldehydes in the presence of AcOH and piperidine produced the addition products, the 1-cyano-2-arylethenesulfonamides, whereas reactions with benzonitrile yielded the 2-amino-1-cyano-2-phenylethenesulfonamides only when done in THF with BuLi. No addition products were isolated from the analogue reactions with 2-hydroxybenzaldehyde (salicylaldehyde). Instead, we obtained 2-imino-2H-chromene-3-sulfonamides with good to excellent yields. These 2H-chromene derivatives allowed a number of transformations, from which the reactions with orthoformates opened an approach to the hitherto unknown benzopyrano[3,2-e] [1,2,4]thiadiazine ring system.     

Effect of Doping and Solution Redox Relays on the Efficiency of Photocathodic Processes at the p-InP/Water Interface

Light-induced interfacial electron transfer from two p-InP electrodes differing in the amount of majority carrier doping to a number of electron relays ( R ) dissolved in aqueous solution was investigated. The material with the lower carrier density (0.71 × 10¹⁸ cm^?3) exhibited much better wavelength response and quantum yield for electron transfer than the electrode doped with 2.3 × 10¹⁸ cm^?3 charge carriers. Using cobalt (III) sepulcrate, Co (sep)³⁺, as an electron relay a polychromatic light to electrical energy conversion efficiency of 18% was obtained. The potential of this relay for use in a regenerative photoelectrochemical cell is briefly discussed.     

Alkylation of heme by the antimalarial drug artemisinin

The peroxide function of artemisinin has been activated by iron(II)-heme generated in situ from iron(III)-protoporphyrin-IX and glutathione, a biologically relevant reductant. In mild conditions, this reaction produced a high yield (85%) of heme derivatives alkylated at alpha-, beta-, and delta-meso positions by a C4-centered radical derived from artemisinin.     

Fluorimetric determination of zirconium with morin

Zirconium can be determination fluorimctrically with morin in 2M hydrochloric acid in the presence of such elements as Al, Be, Ga, Sb, Sn, Th and U, which fluorcsce much less strongly under the conditions, by measuring the fluorescence intensity before and after adding ethylenediaminetetraacetic acid. This substance destroys the fluorescence of zirconium only and the difference in fluorescence intensities corresponds to the concentration of zirconium in solution. The determination of zirconium in the presence of aluminum has especially been studied. Satisfactory accuracy can be obtained even when Al/Zr = 10,000, if the proper morin concentration is used. Iron docs not interfere if reduced to the ferrous state with mercap oacetic acid, Zirconium can be determined in silicate rocks without any separations except those made automatically in tlie sodium carbonate decomposition. Niobium and tantalum should not exceed 0.05%.     

An NMR study of the rotational barriers in cobalt-stabilized carbocations: X-ray crystal structures of (η-C4Ph4)Co-(η-C5H4R), where R is CH3CO, CHO, CH(Bu)OH

Treatment of the aldehyde (η⁴-C₄Ph₄)Co(η⁵-C₅H₄-CHO) (4b) with tert-butyllithium or phenyllithium yields the secondary alcohols (η⁴-C₄Ph₄)Co(η⁵-C₅H₄-CH(R)OH), where R=tert-butyl (5) or phenyl (6). Protonation of 5 and 6 at −80 °C furnishes the deep purple, cobalt-stabilized cations, 7 and 8, respectively, both of which exhibit restricted rotation about the external C₅H₄-CHR⁺ linkage on the NMR time-scale. These data indicate a minimum value for the barrier to rotation of 15 kcal mol⁻¹, but it is certainly much higher, indicating a considerable degree of C-C double bond character. X-ray crystal structures of 4b, 5 and also of the ketone (η⁴-C₄Ph₄)Co(η⁵-C₅H₄-C(O)CH₃ (4a) are reported. The secondary alcohol 5 exhibits disorder in the solid state because of the presence of diastereomers as a consequence of the stereogenic center at the α-carbon and the clockwise or anticlockwise propeller orientations of the tetraphenylcyclobutadiene ligand.