Synthesis and characterization of nickel(II) complexes with potentially pentadentate macrocyclic ligands having N3O2 donor set

Nickel(II) complexes of N₃O₂ donor macrocycles incorporating 17- to 19-membered macrocyclic rings have been prepared. Physical measurements ind     

Crystal-face dependence and photoetching-induced increases of dye-sensitized photocurrents at single-crystal rutile TiO2 surfaces

Dye-sensitized photocurrents at (100)-, (001)-, and (110)-cut TiO(2) rutile surfaces were increased by photoetching of TiO(2), but the increasing ratio strongly depended on the cut crystal faces and the illumination intensity for the photoetching. For the (110)-cut surface, the photocurrent increase was moderately large and in proportion to the increase in the surface area of TiO(2) induced by the photoetching, irrespective of the illumination intensity for the photoetching. On the other hand, the photocurrent increases for the (001)- and (100)-cut surfaces, especially that for the (001)-cut surface, were prominent and largely exceeded the increases in the surface area. The results were explained by taking into account the following factors: (1) The (001)- and (100)-cut surfaces were thermodynamically unstable in contrast to the (110)-cut surface and had thicker inactive surface layers (or higher densities of surface defects), produced by surface reconstruction during heat treatment of TiO(2) at 550 degrees C in a hydrogen atmosphere for getting n-type semiconductivity. (2) Photoetching not only increased the surface area through formation of nanoholes and grooves at the surface but also effectively removed the thin inactive surface layers (or surface defects).     

The number of homomorphisms from a finite abelian group to a symmetric group

ABSTRACT

We present an algorithm to construct the automorphism group of a finite p-group. The method works down the lower exponent-p central series of the group. The central difficulty in each inductive step is a stabiliser computation; we introduce various approaches designed to simplify this computation.     

First enantioselective synthesis of salinipostin A,a marine cyclic enol-phosphotriester isolated from Salinispora sp

Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived Salinispora sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.     

Double nitro-Mannich reaction utilizing in situ generated N-trimethylsilylaldimines: novel four-component one-pot synthesis of nitroimines

Four-component synthesis of nitroimine derivatives (3) via double nitro-Mannich reaction was carried out in which nitroalkane, two moles of aldehyde, and lithium hexamethyldisilazide (LHMDS) were coupled in one-pot. In situ generated N-trimethylsilylaldimine was reacted with nitroalkane dianion followed by the second addition of the resulting nitrogen anion to the aldimine and the subsequent elimination of bistrimethylsilylamine furnished nitoroimine. The reaction was proceeded with erythro selectivity.     

Enantioselective synthesis of phomallenic acid C, an inhibitor of FAS II pathway

Enantioselective synthesis of phomallenic acid C, an inhibitor of bacterial FAS II pathway, was successful. Allenyldiyne structure was constructed by a direct anti-S_N2′ coupling of propargyl mesylate with diynylindium in the presence of palladium catalyst. Enantiomeric purity was determined by Ohrui-Akasaka method to be 83%ee.     

N-heterocyclic carbene ligands in cobalt-catalyzed sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with Grignard reagents

[reaction: see text] N-Heterocyclic carbene/cobalt systems effectively catalyze sequential cyclization/cross-coupling reactions of 6-halo-1-hexene derivatives with trialkylsilylmethyl and 1-alkynyl Grignard reagents, which phosphine and amine ligands did not promote.     

Implementation of pi-pi interactions in molecular dynamics simulation

No explicit pi-pi interaction term has been incorporated in the conventional molecular dynamics (MD) simulation programs in spite of its significant role in the folding of biomolecules and the clustering of organic chemicals. In this article, we propose a technique to emphasize the effect of pi-pi interactions using a function of energy and implement it into an MD simulation program. Several trial calculations show that the pi-pi incorporated program gives improved results consistent with experimental data on atom geometry and has no unfavorable interference with the conventional computational framework. This indicates an importance of the explicit consideration of pi-pi interactions in MD simulation.     

Revised model core potentials of s-block elements

We developed new model core potentials (MCPs) for s-block elements from Na to Ra, in which the outer core (n-1)s and (n-1)p electrons are treated explicitly together with the ns electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all-electron correlation consistent basis sets of Dunning.