Manifestation of circular photogalvanic current by dynamic holography in BaTiO3

We report the first measurement of the photo-galvanic circular current antisymmetric tensor component in BaTiO₃: Co. The measurement gives a value of this coefficient, for extraordinary beam amplification, of 4×10^–9 A/W using a nonstationary measurement technique at a wavelength of 0.632 m.Professor N. Kukhtarev is on leave from the Institute of Physics in the Ukraine and is supported by the NSFDr. G. Dovgalenko is on leave from the IRPA Rotor-Control research laboratory of the Ukraine and is supported by the University of Arkansas     

Synthesis of a new class of chiral 1,5-diphosphanylferrocene ligands and their use in enantioselective hydrogenation

A new family of ferrocenylphosphane ligands has been prepared. Their flexible synthesis allows many structural modifications. The asymmetric induction of these ligands was examined in the hydrogenation of functionalized C=C, C=O, and C=N bonds. The enantioselectivity of the reaction was strongly dependent on the substituent R at the position alpha to the ferrocene moiety. In many cases, both enantiomeric beta-hydroxyesters of the reduction product can be obtained by simply replacing a dimethylamino group in the ligand with a methyl group.     

Characterization of distribution of pi-electrons amongst benzenoid rings for Randić’s “algebraic” Kekulé structures

For benzenoid hydrocarbons the distribution of pi-electrons amongst rings is characterized in the context of Randis mode of assignment attending to the different Kekulé structures. In particular the mean and mean deviation from the mean are considered, and the benzenoids which achieve maximum deviation are identified.     

Austauscher mit cyclischen Polyethern als Ankergruppen—II: Anwendungen

Exchangers with cyclic polyethers as anchor groups have a large range of applications such as separations of cations with a common anion, of anions with a common cation, and of neutral organic compounds, and the determination of water by elution chromatography. Some crown ether monomers, especially 4- and 4,4′-alkyl-substituted benzo-derivatives are suitable for extractions and their adducts with heteropoly acids are used as liquid ion-exchangers. The exchangers are also applied in thin-layer chromatography and thin-layer electrophoresis. Furthermore the exchangers are successfully used in preparative chemistry, e.g., in salt conversions in order to isolate salts which are difficult to prepare by other means, in isolation and purification of organic compounds, and for anion activation in organic reactions.     

Dissociation of hydrogen fluoride in HF(H(2)O)(7)

We have previously demonstrated that H-bond arrangement has a significant influence on the energetics, structure and chemistry of water clusters. In this work, the effect of H-bond orientation on the dissociation of hydrogen fluoride with seven water molecules is studied by means of graph theory and high level ab initio methods. It is found that cubic structures of HF(H(2)O)(7) are more stable than structures of other topologies reported in the literature. Electronic calculations on all possible H-bond orientations of cubie-HF(H(2)O)(7) show that ionized structures are energetically more favorable than nonionized ones. This is an indication that seven water molecules might be capable of ionizing hydrogen fluoride.     

Synthesis and structure of a stabilized 10-membered cyclic enediyne

The synthesis and structure of an acetal protected 10-membered cyclic enediyne-1,2-diol rac-10 is reported. The conformational constrain of the unsaturated macrocycle by the acetal protection group prevents the thermal cyclization reaction of the endiyne during synthesis and purification.     

Novel fluorinated block copolymer architectures fuelled by atom transfer radical polymerization

Block copolymers based on poly(pentafluorostyrene), PFS, in various numbers and of different lengths, and polystyrene are prepared by atom transfer radical polymerization (ATRP). Di- and triblock copolymers with varying amounts of PFS were synthesized employing either 1-phenylethylbromide or 1,4-dibromoxylene as initiators for ATRP. Diverse bromo(ester) (macro)initiators were also devised and involved in the formulation of fluorinated pentablock as well as amphiphilic triblock copolymers with a central polyether segment. Amphiphilic star-shaped fluoropolymers, hydrophobic fluorinated nanoparticles, or segmented fluorinated star-shaped block copolymers are further designed by use of different multifunctional initiators. The composition of the novel materials with PFS is determined by combination of SEC and ¹H NMR. Glass transition temperatures and thermal stabilities of the hydrophobic star-shaped PFSs on a six arm dipentaerythritol core are investigated in a wide range of molecular masses and further discussed.