Formation of ice nanotube with hydrophobic guests inside carbon nanotube

A composite ice nanotube inside a carbon nanotube has been explored by molecular-dynamics and grand canonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates.     

Direct C-H arylation of (hetero)arenes with aryl iodides via rhodium catalysis

A new method for the catalytic C-H arylation of heteroarenes and arenes that manifests high activity paired with reasonably broad scope was developed. Under the catalytic influence of RhCl(CO){P[OCH(CF3)2]3}2 and Ag2CO3, the direct C-H arylation of heteroarenes/arenes with aryl/heteroaryl iodides took place to afford a range of biaryls in good to excellent yields with high regioselectivity. Thiophenes, furans, pyrroles, indoles, and alkoxybenzenes are applicable in this arylation protocol.     

On the thermodynamic stability and structural transition of clathrate hydrates

Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure.     

Synthesis and inhibitory effect on fat accumulation of (-)-ternatin derivatives modified in the beta-OH-D-Leu(7) moiety

An efficient synthesis of (-)-ternatin derivatives directed toward their SAR at the beta-OH-D-Leu(7) moiety and their biological activities against 3T3-L1 murine adipocytes are described.     

Diels–Alder derivatization for sensitive detection and characterization of conjugated linoleic acids using LC/ESI-MS/MS

The utility of Diels–Alder derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) for liquid chromatography/electrospray ionization tandem mass spectrometry of conjugated linoleic acids (CLAs) was examined. PTAD rapidly reacted with the CLAs, and the resulting derivatives were highly responsive in electrospray ionization mass spectrometry operating in the positive-ion mode. The derivatives produced characteristic product ions during tandem mass spectrometry, which enabled the sensitive detection [limit of detection 18 fmol (signal-to-noise ratio of 5)] and the identification of the conjugated diene position. The PTAD derivatization also significantly increased the reversed-phase liquid chromatography separation selectivity for the most biologically active CLA isomers: cis-9,trans-11-CLA and trans-10,cis-12-CLA. The PTAD derivatization was applied to analyses of food and biological samples; the major CLAs in milk and beef fat samples were successfully identified, and trace amounts of CLAs in human saliva were detected with a simple pretreatment and short analysis time.