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A simple and efficient diastereoselective synthesis of methylenecyclopropanes is described, in which boron-homologation and allylboration are merged into a one-pot process, starting from in situ generated cyclopropenyllithium species. This unprecedented methodology opens a new route to strained alkylidenecycloalkanes containing a quaternary stereocenter, in high yields and excellent diastereomeric ratios. [ABSTRACT FROM AUTHOR]

Nanosized AlPO4-18 is synthesized from clear precursor solutions; a complete transformation from amorphous to crystalline colloidal particles is observed after 60, 20 and 18 h at 100, 150, and 170 °C, respectively. The evaluation of the long-range ordering of nanocrystals as a function of crystallization time was followed by X-ray diffraction and dynamic light scattering. The time-dependent 27Al NMR measurements in the liquid phase before and after purifications with different crystallization times show that the tetrahedrally coordinated Al is formed at RT prior to hydrothermal treatment indicating the formation of crystalline phase. The mean hydrodynamic radius of the amorphous aluminophosphate entities and the crystalline AlPO4-18 particles does not change during the entire process of crystal growth. Further these AlPO4-18 nanocrystals were employed for the preparation of thin films on silicon wafers via spin coating of stable AlPO4-18/EtOH solutions, and additional crystal growth of the seeded layers at elevated temperature was carried out. The structural evolution of the thin films was studied with grazing incidence diffraction using synchrotron X-ray radiation. The orientation of growing crystals is governed by the preferred orientation of the seeded particles deposited by spin coating approach. [Copyright &y& Elsevier]

Evaporation-induced self-assembly via spin coating has been employed for the formation of mesoporous films from preformed pure-silica and Fe-containing silica/triblock copolymer/ethanol solutions. The X-ray diffraction results reveal the formation of a Pn3m cubic mesophase structure on silicon wafer. The films are smooth and homogeneous without any cracks or corrugations. Thus, cubic pure-silica and Fe-containing mesoporous films have been obtained having an accessible mesoporous channel system suitable for growth of carbon nanotubes by catalytic decomposition of acetylene. The Raman spectroscopy results show that multiwalled carbon nanotubes are formed on the Fe-containing mesoporous film supports. [Copyright &y& Elsevier]

Novel tertiary phosphines R'PR2 with additional functionalities in the substituent R have been designed and prepared according to literature procedures. The coordination behavior of the additional functionality in the organic moiety and the phosphorus atom towards different Cu(I) salts was investigated. These reactions resulted in polynuclear complexes with unexpected structures involving Cu(I) atoms with different coordination numbers in the same compound. [ABSTRACT FROM AUTHOR]

In medical and pharmaceutical science phosphonic acids and phosphonates play an important role with regard to their wide application in various drugs as medicines against osteoporosis or antiviral agents. In the course of the investigations on the coordination chemistry of biologically active phosphonates different salts of the phosphonoformate anion were prepared via hydrolysis of corresponding esters under basic conditions. Depending on the reaction and crystallization conditions, different sodium salts with the phosphonoformate moiety were obtained and structurally characterized. [ABSTRACT FROM AUTHOR]

A graphical abstract for the study "Highly Diastereoselective Approach to Methylenecyclopropanes via Boron-Homologation/Allylboration Sequences," is presented.

Primary and secondary aliphatic, alkylaromatic, cyclic, and organoelement alcohols are efficiently oxidized by tert-butyl hydroperoxide in the presence of both equimolar and catalytic quantities of chromium tetra-tert-butoxide (СН, 20°С). α-Diols containing tertiary hydroxyl groups interact with this system via oxidative splitting of the carbon scaffold. The oxidation includes the stages of formation and decomposition of chromium-containing peroxy compounds. Further transformations of the carbonyl compounds depend on the structure of radicals in the molecules. [ABSTRACT FROM AUTHOR]

An efficient synthetic protocol affording symmetrical 1,2- bis (pyridine-2/3/4-yl)methyldiselanes from pyridine-2/3/4-carbaldehyde in high yields at room temperature, without using highly toxic hydrogen selenide, has been developed. The synthesis involves the reductive selenation of pyridine-2/3/4-carbaldehyde with sodium hydrogen selenide, NaHSe in the presence of piperidine hydrochloride followed by NaBH 4 reduction under mild conditions. Primary screening of the anti-proliferative activity of the newly synthesized compounds against several mammalian cell lines and pathogenic strains has been carried out. The crystal structure of 1,2- bis (pyridine-3-yl)methyldiselane has been established by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The synthesis of novel, chignolin-derived peptides comprising the azobenzene photoswitch [3-(3-aminomethyl)phenylazo]phenylacetic acid (AMPP) is reported. Reversible photoswitching behavior led to folding into β-hairpin-like structures, as unequivocally demonstrated by CD, FT-IR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Organophosphates are well known to have toxic properties amongst other favorable chemical and physical properties. This holds true for pesticides and especially chemical warfare agents. The present study focusses on the toxicity and bioactivity of nerve agent VG and related isomers which were designed by us in need of nontoxic and non-bioactive surrogate substances for training reasons. A previous study revealed that some of the isomers are ideal model substances for e.g. vapor pressure determination. However, the toxicity and bioactivity data for these new compounds are still missing. Thus, we used the classical Ellman essay to determine the AChE and BuChE toxicity and Vibrio fisheri bacteria to test aquatic toxicity. Additionally, we made use of QSAR-methods to model toxicity data of other species e.g. Daphnia magna. By now we are able to adjust the toxicity in a wide range by choosing proper substituents. [ABSTRACT FROM AUTHOR]

Ionic compounds containing phosphorus-based cations represent an important new direction in the fundamental chemistry of nonmetal elements. In this work, we explored the reactivity of phosphino-phosphonium cations with sulfur and selenium, with a view towards new synthetic methods for phosphorus-chalcogen cations. We present several new cations which have been identified by 31P NMR spectroscopy and single crystal x-ray diffraction, that are analogous to the recently reported chalcogenides of phosphanylboranes. We also present new diphosphonium-diselenide cations which have been formed through a unique redox equilibrium of triphenylantimony(V) bistriflate and trialkylphosphineselenides on one side and the diphosphonium diselenide cations and triphenylantimony(III) on the other side. [ABSTRACT FROM AUTHOR]

Reactions of phosphines with iodomethane are well known and well investigated. The resulting phosphonium salts are used in Wittig reactions or to form ionic liquids. Reaction rates depend on the Tollman parameter as well as on steric factors. Reactions with iodomethane occur spontaneously within a few hours. We have found that the corresponding reactions of phosphines with fluoroiodomethane are significantly slower. Reaction times range from one day up to 11 days. The resulting phosphonium salts are stable towards air and water and show also low aqueous toxicity with respect to Vibrio fisheri bacteria. Due to the strong electronegativity of the fluorine atom and its similarity to an OH group, interesting crystal structures were observed. [ABSTRACT FROM AUTHOR]

Highlighted on the cover of this issue is a collaboration between the groups of Jan Weigand and Michael Ruck at TU Dresden, Hellmut Eckert and Thomas Wiegand at Westfälische Wilhelms-University Münster, and Christian Ochsenfeld and Konstantin Karaghiosoff at Ludwig Maximilians University Munich (all Germany), who teamed up to uncover the novel selenium cation, [P3Se4]+. Three distinct syntheses and detailed information on its structural, electronic and dynamic properties resulted from the combination of the groups' different perspectives (cover design by Dr. Kai-Oliver Feldmann from the Weigand group). Read the full text of the article at . [ABSTRACT FROM AUTHOR]