Ordered mesoporous phosphosilicate glass electrolyte film with low area specific resistivity

Ordered mesoporous phosphosilicate glass electrolyte film exhibiting low area specific resistivity (ASR) compared with those of Nafion has been synthesized using non-ionic surfactant as the structure-directing agent.     

Recent progress in biphasic catalytic systems using ionic liquids

Catalytic reactions in two liquid phases containing ionic liquids (ILs), in which organic reactions proceed in the ILs phase and products are extracted to the other liquid phase, are efficient and environmentally benign. This short review briefly reports the development of catalytic application in biphasic systems containing ILs in the last two years. Recent progress for the functionalization of ILs themselves and combinations of homogeneous and heterogeneous catalysts with ILs are described. Prospects and future challenges are also addressed.     

In Vivo Spectrum of UVC‐induced Mutation in Mouse Skin Epidermis May Reflect the Cytosine Deamination Propensity of Cyclobutane Pyrimidine Dimers

Although ultraviolet radiation (UVR) has a genotoxicity for inducing skin cancers, the skin may tolerate UVC component because the epidermal layer prevents this short wavelength range from passing through. Here, UVC genotoxicity for mouse skin was evaluated in terms of DNA damage formation and mutagenicity. UVC induced UVR photolesions and mutations remarkably in the epidermis but poorly in the dermis, confirming the barrier ability of the epidermis against shorter UVR wavelengths. Moreover, the epidermis itself responded to UVC mutagenicity with mutation induction suppression, which suppressed the mutant frequencies to a remarkably low, constant level regardless of UVC dose. The mutation spectrum observed in UVC‐exposed epidermis showed a predominance of UV‐signature mutation, which occurred frequently in 5′‐TCG‐3′, 5′‐TCA‐3′ and 5′‐CCA‐3′ contexts. Especially, for the former two contexts, the mutations recurred at several sites with more remarkable recurrences at the 5′‐TCG‐3′ sites. Comparison of the UVC mutation spectrum with those observed in longer UVR wavelength ranges led us to a mechanism that explains why the sequence context preference of UV‐signature mutation changes according to the wavelength, which is based on the difference in the mCpG preference of cyclobutane pyrimidine dimer (CPD) formation among UVR ranges and the sequence context‐dependent cytosine deamination propensity of CPD.     

Enantiomeric Excess Determination for Monosaccharides Using Chiral Transmission to Cold Gas-Phase Tryptophan in Ultraviolet Photodissociation

Chiral transmission between monosaccharides and amino acids via photodissociation in the gas phase was examined using a tandem mass spectrometer fitted with an electrospray ionization source and a cold ion trap in order to investigate the origin of the homochirality of biomolecules in molecular clouds. Ultraviolet photodissociation mass spectra of cold gas-phase noncovalent complexes of the monosaccharide enantiomers glucose (Glc) and galactose (Gal) with protonated l-tryptophan H⁺(l-Trp) were obtained by photoexcitation of the indole ring of l-Trp. l-Trp dissociated via C_α–C_β bond cleavage when noncovalently complexed with d-Glc; however, no dissociation of l-Trp occurred in the homochiral H⁺(l-Trp)(l-Glc) noncovalent complex, where the energy absorbed by l-Trp was released through the evaporation of l-Glc. This enantioselective photodissociation of Trp was due to the transmission of chirality from Glc to Trp via photodissociation in the gas-phase noncovalent complexes, and was applied to the quantitative chiral analysis of monosaccharides. The enantiomeric excess of monosaccharides in solution could be determined by measuring the relative abundance of the two product ions in a single photodissociation mass spectrum of the cold gas-phase noncovalent complex with H⁺(l-Trp), and by referring to the linear relationships derived in this work.

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Novel and practical asymmetric synthesis of β2,3-amino esters using asymmetric Michael addition of chiral amine

A practical method for the synthesis of chiral β^2,3-amino esters having various substituents was developed, which is characterized by an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,β-unsaturated esters. We found that a highly face-selective protonation occurred by the quick addition of water to the enolate intermediate derived from the Michael addition reaction to afford N-protected β^2,3-amino esters in moderate to excellent yields. This finding was made possible by the facile preparation of geometrically pure trisubstituted (E)-α,β-unsaturated esters, which was established recently by our group. The subsequent deprotection of the amino group in the Michael adduct by using N-iodosuccinimide (NIS) efficiently provided β^2,3-amino esters having various substituents.     

Convergent synthesis of stereoisomers of THF ring moiety of acetogenin thiophene analogue and their antiproliferative activities against human cancer cell lines

The convergent synthesis of thiophene-3-carboxamide analogues of annonaceous acetogenins was accomplished through the asymmetric alkynylation of a 2-formyl THF ring fragment with an alkyne having a thiophene ring as the key step. Eight stereoisomers of the THF ring moiety were synthesized by this convergent route and their antiproliferative activities against 39 human cancer cell lines were evaluated. It was revealed that derivatives having the threo configuration between C17–C18 positions showed more potent activities than the corresponding erythro ones.     

Synthesis and Antiaromatic Properties of Highly Planar Dithiaamethyrin

2,5‐Bis(4‐propyl‐2‐pyrrolyl)thiophene was reacted with aryl aldehydes to afford large porphyrinoids; [24]dithiaamethyrin(1.0.0.1.0.0) and [36]trithianonaphyrin(1.0.0.1.0.0.1.0.0). X‐ray crystallography of the dithiaamethyrin revealed a highly planar ring structure with mean plane deviation (MPD) value of 0.053 Å. A large positive NICS(0) value (+13.9 ppm) calculated for this planar 24π system unambiguously indicates an antiaromatic character that is consistent with a remarkably low field ¹H chemical shift of the inner NH proton at 24.0 ppm. The magnitude of the paratropic ring current effect in the 24π amethyrin framework in the free base form and the diprotonated form was discussed on the basis of the MPD value and the NICS value. The present dithiaamethyrin is much more strongly antiaromatic than the dodecaalkylamethyrin in their free base forms, but the order inversed in their diprotonated forms.     

Conjugated Oligomers and Polymers Sheathed with Designer Side Chains

Conjugated polymers (CPs) are often referred to as molecular wires because of their quasi one‐dimensional electronic wavefunctions delocalized along the polymer chains. However, in the solid state, CPs tend to self‐assemble through π‐stacking, which greatly attenuates the one‐dimensional nature. By molecular design, CPs can be molecularly insulated just like electric power cords, resulting in so‐called “insulated” molecular wires (IMWs). In this Focus Review, we will discuss their unique photophysical, electronic, and mechanical properties which originate from the absence of π‐stacking.