Diels-Alder chemistry on alkene functionalized films

A substrate-independent method has been devised for ring formation at solid surfaces. This entails the aminolysis reaction of allylamine with maleic anhydride pulsed plasma polymer films to yield terminal alkene groups at the surface. Subsequent exposure to 1,3-cyclohexadiene leads to a Diels-Alder type (4 + 2) cycloaddition reaction to give a mixture of endo- and exo-bicyclo[2.2.2]oct-2-ene rings.     

Investigating the interface of superhydrophobic surfaces in contact with water

Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface.     

Gravimetric separation of titanium and zirconium from Niobium with Phenylacetylhydroxamic acid

Phenylacetylhydroxamic acid is used to separate titanium and zirconium from niobium in an oxalate medium at pH 6.5–7.5 in presence of ammonium chloride at room temperature. The method is accurate when the ratio of (TiO₂ + ZrO₂) : Nb₂O₅ is 10 : 1 to 1 : 1 ; when the niobium concentration is higher, reprecipitation is necessary. Tantalum, citrate, tartrate, lactic acid, EDTA, and a large excess of oxalate interfere.     

Structural changes by sulfoxidation of phenothiazine drugs

Summary The side-chain conformations of psychoactive phenothiazine drugs in crystals are different from those of biologically inactive ring sulfoxide metabolites. This study examines the potential energies, molecular conformations and electrostatic potentials in chlorpromazine, levomepromazine (methotrimeprazine), their sulfoxide metabolites and methoxypromazine. The purpose of the study was to examine the significance of the different crystal conformations of active and inactive phenothiazine derivatives, and to determine why phenothiazine drugs lose most of their biological activity by sulfoxidation. Quantum mechanics and molecular mechanics calculations demonstrated that conformations with the side chain folded over the ring structure had lowest potential energy in vacuo, both in the drugs and in the sulfoxide metabolites. In the sulfoxides, side chain conformations corresponding to the crystal structure of chlorpromazine sulfoxide were characterized by stronger negative electrostatic potentials around the ring system than in the parent drugs. This may weaken the electrostatic interaction of sulfoxide metabolites with negatively charged domains in dopamine receptors, and cause the sulfoxides to be virtually inactive in dopamine receptor binding and related pharmacological tests.     

Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene ring system

Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene system from the derivatives afforded by the Baylis-Hillman reaction of 3-(2-bromophenyl)-4-isoxazolecarbaldehydes is described.     

A new one-pot three-component condensation reaction for the synthesis of 5-deaza-5,8-dihydropterins

The one-pot cyclocondensation of 2,6-diaminopyrimidin-4-one, an aromatic or aliphatic aldehyde and a beta-ketoester in acetic acid, or dimethyl sulfoxide in the presence of zinc(II) bromide, under thermal conditions provided dihydropyrido[2,3-d]pyrimidin-4(3H)-ones in good yield and with total regiocontrol.     

The effect of a magnetic field on the singlet/triplet ratio in geminate ion recombination

Excited state formation by ion recombination in solutions of fluorene in squalene has been studied by pulse radiolysis at the center of a large electromagnet. The products of the slower part of the ion recombination are affected by an applied magnetic field. The fluorescence yield increases by a factor of about 1.5 whereas the triplet yield decreases.