Synthesis of dinuclear palladium complexes having two parallel isocyanide ligands,and their application as catalysts to pyrrole formation from tert-butylisocyanide and alkynes

Novel dinuclear palladium complexes having two isocyanide ligands were synthesized by using a binucleating ligand, N,N′-bis[2-(diphenylphsphino)phenyl]formamidinate (dpfam). The structure of [Pd₂(μ-dpfam)(tert-BuNC)₂]Cl was confirmed by X-ray analysis, showing that the Pd–Pd bond length of 2.5824(3) Å falls well within the range of those for known dipalladium complexes having the edge-sharing structure and two isocyanides coordinate to palladium in almost parallel and in close proximity. The dinuclear complex [Pd₂(μ-dpfam)(tert-BuNC)₂]PF₆ served as catalyst for pyrrole formation from tert-butylisocyanide and various alkynes.     

Creation and application of psychoactive designer drugs data library using liquid chromatography with photodiode array spectrophotometry detector and gas chromatography-mass spectrometry

In order to quickly confirm a potentially hazardous psychoactive designer drug (a compound in which part of the molecular structure of a stimulant or narcotic has been modified), we created a psychoactive drugs data library by performing analysis using liquid chromatography with photodiode array spectrophotometry (LC/PDA) and gas chromatography-mass spectrometry (GC/MS). The data in this library consist of the LC capacity factor (k′) ratios in relation to the internal standard, the ultraviolet (UV) spectra and the MS spectra of 104 compounds. By performing a comparative study of the data in this report with the analytical data for commercial and illegal drug products, it is possible to quickly identify the psychoactive designer drugs in 205 purchased products by using the library. Further, it is possible to analogize the structure of drugs for which there is no matching data in the library using similar data.Furthermore, when structural isomers of controlled substances have detected from the presented library, similarity of their biological effects on human will be predicted, thus leading to regulate their public circulation. Examples of these types of isomers include, for instance, the narcotic 3,4,5-trimethoxyamphetamine (TMA) and its positional isomers 2,4,5-trimethoxyamphetamine (TMA-2) and 2,4,6-trimethoxyamphetamine (TMA-6), or the narcotic 1-(3-chlorophenyl)piperazine (3CPP) and its isomers 1-(o-chlorophenyl)piperazine (2CPP) and 1-(p-chlorophenyl)piperazine (4CPP). Differentiation of these compounds is necessary in regulating them, and we report here the results of a study of a method to confirm these compounds using the present library.     

Luminol chemiluminescence under interaction with heteropoly acids

Interaction of luminol with phosphomolybdic, phosphovanadomolybdic and silicomolybdic acids was studied by examination of chemiluminescence spectra, measurement of ESR spectra, investigation of reaction order, and elucidation of inhibition effects. A scheme of the reaction mechanism is proposed.     

Convergence of a finite element/ALE method for the Stokes equations in a domain depending on time

We consider the approximation of the unsteady Stokes equations in a time dependent domain when the motion of the domain is given. More precisely, we apply the finite element method to an Arbitrary Lagrangian Eulerian (ALE) formulation of the system. Our main results state the convergence of the solutions of the semi-discretized (with respect to the space variable) and of the fully-discrete problems towards the solutions of the Stokes system.     

Electrical conductivity modulation coupled to a high-spin-low-spin conversion in the molecular system [FeIII(qsal)2][Ni(dmit)2]3.CH3CN.H2O

The synergy between the electrical conductivity within the stacks of Ni(dmit)2 in the newly electrocrystallized [Fe(qsal)2][Ni(dmit)2]3.CH3CN.H2O and the spin conversion of Fe(qsal)2 is evidenced. In addition, the presence of a light-induced excited spin state trapping effect suggests that this complex is a prototypal photoswitchable spin-crossover molecular conductor.     

Application of dual counter-current chromatography for rapid sample preparation of N-methylcarbamate pesticides in vegetable oil and citrus fruit

Dual counter-current chromatography (dual CCC) has been successfully applied to rapid sample preparation for the simultaneous determination of residual carbaryl, fenobucarb and methomyl in vegetable oil and citrus fruit. The citrus fruit samples were extracted with n-hexane solution containing stable isotopically labeled internal standards (methomyl-d3, fenobucarb-d3 and carbaryl-d9), and applied to dual CCC using a two-phase solvent system of n-hexane-acetonitrile to purify the carbamate pesticides from aliphatic sample matrix. The coiled column was rotated at 420 rpm, the lower mobile phase was introduced through the head toward the tail, and the upper mobile phase in the opposite direction. Due to the high partition efficiency of dual CCC, the lower phase fraction collected from 2 to 5 min after injection could be subjected to flow-injection tandem mass spectrometry directly after concentration. Repetitive sample injection can be performed at high reproducibility without a risk of contamination from the compounds retained in the column.     

Palladium-catalyzed C-H homocoupling of bromothiophene derivatives and synthetic application to well-defined oligothiophenes

Synthesis of oligothiophenes of well-defined structures that possess 2-8 thiophene units is performed with a new synthetic strategy involving C-H homocoupling of bromothiophenes and cross-coupling with organostannanes. Tolerance of the carbon-bromine bond to the palladium-catalyzed C-H homocoupling results in oligothiophenes bearing C-Br bonds at the terminal thiophene rings, which allow further transformation by the catalysis of a transition-metal complex.     

Particle design of three-component system for sustained release using a 4-fluid nozzle spray-drying technique

We prepared composite particles of acetaminophen (Act) with chitosan (Cht) and hydroxypropylmethylcellulose phthalate (HPMCP) as a carrier using a newly developed 4-fluid nozzle spray-dryer. Cht dissolves in acid solutions and forms a gel, but it is insoluble in alkaline solutions. On the other hand, HPMCP is insoluble in acid solutions, but it dissolves in alkaline solutions. Therefore, we tested a preparation of controlled release composite particles using the characteristics of these carriers. Act and Cht mixtures in prescribed ratios were dissolved in an acid solution. Composite particles of Act and HPMCP in prescribed ratios were dissolved in alkaline solutions. We evaluated the composite particles of the three components (Act, Cht, and HPMCP) by preparing solid dispersions using a 4-fluid nozzle spray-dryer. Observation of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray-drying process had atomized to several microns and had all become spherical. We investigated the physical properties of the composite particles by powder X-ray diffraction, differential scanning calorimetry, and dissolution rate analysis to clarify the effects of crystallinity on the dissolution rate. Powder X-ray diffraction peaks and the heat of fusion of Act in the spray-dried samples decreased in proportion to the carrier content, indicating that the drug was amorphous. These results indicate that the Act-Cht-HPMCP system formed a solid dispersion. Furthermore, we investigated the interaction between the drug and the carrier using FT-IR analysis. FT-IR spectroscopy of the Act solid dispersions suggested that the Act carbonyl and Cht amino groups formed a hydrogen bond. On the other hand, interaction by hydrogen bond was observed between the carbonyl group of HPMCP with the amino group of Act. In the three-component Act-Cht-HPMCP system, the 4-fluid nozzle spray-dried preparation with a mixing ratio of 1 : 2.5 : 2.5 obtained sustained release preparation in all pH test solutions.     

Semisynthesis of isetexane diterpenoid analogues and their cytotoxic activity

Isetexane diterpene analogues were semisynthesized from demethylsalvicanol isolated from Perovskia abrotanoides (Labiatae). The structure and cytotoxic activity relationships (SAR) of the natural parent diterpene, demethylsalvicanol, and its semisynthetic analogues were studied by using P388 murine leukemia cells.