Measurement of circular dichroism spectra of liquid/liquid interface by centrifugal liquid membrane method.

The direct measurement of the circular dichroism (CD) spectra of liquid/liquid interface has been achieved for the first time by the centrifugal liquid membrane (CLM) method combined with a conventional CD spectropolarimetry. In the sample chamber of the CD spectropolarimeter, a cylindrical glass cell containing small amounts of organic and aqueous phases was rotated at ca. 7000 rpm to generate a two-phase liquid membrane with a high specific interfacial area. The CD spectra of the J-aggregate of protonated 5,10,15,20-tetraphenylporphyrin formed at the toluene/sulfuric acid interface in the rotating cell have been measured. The results demonstrated the novelty and advantages of this method.     

Effect of core-shell micelle formation on the redox properties of phenothiazine-labeled poly(ethyl glycidy ether)-block-poly(ethylene oxide)

Redox properties of phenothiazine-labeled poly(ethyl glycidy ether)-block-poly(ethylene oxide) (PT-EGE_n-b-EO_m) are reversibly changed by core-shell micelle formation. In the temperature range higher than the critical micellization temperature (cmt), the anodic potential of PT group positively shifts and concomitantly its anodic current decrease, or levels off compared to those of the reference polymer PT-EO_m without the thermo-responsive EGE_n segment. The former alteration is caused by incorporation of hydrophobic PT groups into a core of the micelle and the latter by the decrease in the diffusion coefficient of PT groups due to formation of the core-shell micelles. The cmt value and the temperature-dependent alteration in the redox properties strongly depend on the polymer structure, especially the length of thermo-responsive EGE_n segment. The electrochemically determined hydrodynamic radii of the polymer aggregates seem to be overestimated, compared to the values reported for the aggregates of other thermo-responsive polymers with similar molecular weights, implying the presence of electrochemically inactive PT groups in the copolymers having longer thermo-responsive segments.     

Diversification of shotgun process

Three protocols for shotgun process are put forth in which simultaneous multi-fold reactions occur exclusively to each other. The first one involves simple combination of selective and non-selective reactions. Even if the simple protocol fails to give rise to the high selectivity, satisfactory outcome can be achieved by kinetic control or adjustment of functional groups.     

One‐Shot Double Elimination Process: A Practical and Concise Protocol for Diaryl Acetylenes

A variety of diaryl acetylenes were obtained in good yields when lithium hexamethyldisilazide was added to a solution of arylmethyl sulfone, aryl aldehyde, and chlorodiethylphosphate in THF. In this one‐shot process, a number of transformations such as aldol reaction, phosphorylation of aldolate, and double elimination of the resulting β‐substituted sulfone proceeded successively to afford the desired acetylenes. The one‐shot process was accelerated by the substitution of halogen atoms on the phenyl groups, and unsymmetrically substituted diaryl acetylenes were obtained without contamination of the dehalogenated products. Diaryl acetylenes with other substituents such as CF₃, ethoxycarbonyl, dimethylamino, TMS‐acetylene groups, as well as pyridinyl and thienyl moieties were also accessible with this method. However, methoxy‐substituted compounds were obtained in moderate yields under the same conditions, but the yields were increased when lithium diisopropylamide was used instead.     

Methane partial oxidation to formaldehyde with oxygen over SiO2-supported molybdenum oxide catalysts

The formation rate of formaldehyde increases with increasing surface area of SiO₂ support, but the selectivity does not. From the characterization of catalysts using XRD, SEM and Raman spectroscopy, highly dispersed molybdenum oxide was considered to be much more active for the formation of formaldehyde than crystallite forms of MoO₃.     

A facile method for the stereoselective preparation of (1E,3E)-4-substituted-1-amino-1,3-dienes via 1,4-elimination

The 1,4-elimination reaction of 1-amino-4-methoxy-(2Z)-alkenes is shown to proceed with high (1E,3E)-stereoselectivities to afford the corresponding 4-substituted-1-amino-1,3-dienes in good yield. The scope and stereochemical features of the synthetic method are described.     

Circularly polarized luminescence (CPL) characteristics of hydrophobic pyrene derivatives/γ-cyclodextrin (γ-CD) complexes in aqueous solution dissolved by grinding

Circularly polarized luminescence (CPL) organic dyes are currently receiving a great interest, but there are still not many reported observations of CPL spectra of hydrophobic dyes from aqueous solution. We have prepared hydrophobic pyrene derivatives and dissolved them into aqueous solutions with γ-cyclodextrin (γ-CD) by using grinding technique. Among these derivatives, (pyrene-1-carbonyl)serine (PySer) forms a spatially restricted dimer in the hydrophobic chiral cavity of γ-CD and exhibits excimer emission with a high quantum yield of Φ_f?=?0.68. In addition, circular dichroism and CPL signals were induced for the complex. The strong g_CPL value of g_CPL?=?+?2.2?×?10^?3 was obtained, which may be attributed to the interaction between the hydroxyl groups in the side chain of PySer with those of γ-CD and it strengthens the chiral dimeric structure.

Graphic abstract

     

Subincanadines A-C,novel quaternary indole alkaloids from Aspidosperma subincanum

Three novel quaternary indole alkaloids with an unprecedented 1-azoniatricyclo[4.3.3.0(1,5)]undecane moiety, subincanadines A-C (1-3), as well as two new indole alkaloids with a 1-azabicyclo[5.2.2]undecane moiety, subincanadines D (4) and E (5), and a new indole alkaloid with a 1-azabicyclo[4.3.1]decane moiety, subincanadine F (6), have been isolated from the barks of Aspidosperma subincanum Mart, and the structures of 1-6 and the stereochemistry of 1-3 were elucidated by spectroscopic data and chemical means.