Synthesis and Structural Analysis of (Imido)vanadium Dichloride Complexes Containing 2-(2'-Benz-imidazolyl)pyridine Ligands: Effect of Al Cocatalyst for Efficient Ethylene (Co)polymerization.

(Imido)vanadium(V) dichloride complexes containing 2-(2'-benzimidazolyl)-6-methylpyridine ligand (L) of type V(NR)Cl(L) [R = 1-adamantyl (Ad, ), CH (), and 2,6-MeCH ()] have been prepared, and their structures were determined by X-ray crystallography as distorted trigonal bipyramidal structures around vanadium. Reactions with ethylene using in the presence of methylaluminoxane (MAO) afforded a mixture of oligomer and polymers, and the compositions were affected by the imido ligand employed. By contrast, exhibited remarkable catalytic activities for ethylene polymerization in the presence of MeAlCl; the phenylimido complex () exhibited the highest activity [80 100 kg-PE/mol-V·h turn over frequency (TOF, 2 850 000 h, 792 s)].

High-Contrast Imaging of Intermediate-Mass Giants with Long-Term Radial Velocity Trends.

A radial velocity (RV) survey for intermediate-mass giants has been operated for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct imaging observations can help clarify what objects generate these RV trends.

Isolation of N,N-dimethyl and N-methylserotonin 5-O-β-glucosides from immature Zanthoxylum piperitum seeds.

Two serotonin derivatives, N,N-dimethylserotonin 5-O-β-glucoside (1a) and N-methylserotonin 5-O-β-glucoside (1b) were isolated from immature seeds of Zanthoxylum piperitum. Their structures were determined by multi-step conversion reactions and spectroscopic analyses. Immature seeds of Z.

Evaluation of iodinated and brominated [11C]styrylxanthine derivatives as in vivo radioligands mapping adenosine A2A receptor in the central nervous system.

In vivo assessment of the adenosine A2A receptors localized in the striatum by PET or SPECT offers us a new diagnostic tool for neurological disorders. In the present study, we evaluated the potential of iodinated and brominated styrylxanthine derivatives labeled with 11C as an in vivo probe. [7-Methyl-11C]-(E)-3,7-dimethyl-8-(3-iodostyryl)-1-propargylxan thine ([11C]IS-DMPX) and [7-methyl-11C]-(E)-8-(3-bromostyryl)-3,7-dimethyl-1-propargylxa nthine ([11C]BS-DMPX) were prepared by the 11C-methylation of corresponding 7-demethyl derivatives.

Synthesis of 2-imidazolidinylidene propanedinitrile derivatives as stimulators of gastrointestinal motility--II.

In a previous paper, we reported that a novel ranitidine derivative 2 (fumarate: KW-5092), which had a 2-imidazolidinylidene propanedinitrile moiety (A), showed potent gastrointestinal motility enhancing activity. In order to obtain more potent gastrointestinal motility enhancing agents than compound 2 and to examine the effects of various substituents both at a nitrogen atom (B) in the 2-imidazolidinylidene propanedinitrile moiety and a basic nitrogen atom (C), compounds 5-29 were synthesized and evaluated for acetylcholinesterase (AChE) inhibitory activity and potentiating action on electrically stimulated contractions of guinea pig ileum. Introduction of alkyl, benzyl, aryl or acyl groups to the nitrogen (B) or (C), remarkably influenced both activities.