3D interconnected ionic nano-channels formed in polymer films: self-organization and polymerization of thermotropic bicontinuous cubic liquid crystals

Thermotropic bicontinuous cubic (Cub(bi)) liquid-crystalline (LC) compounds based on a polymerizable ammonium moiety complexed with a lithium salt have been designed to obtain lithium ion-conductive all solid polymeric films having 3D interconnected ionic channels. The monomer shows a Cub(bi) phase from -5 to 19 °C on heating. The complexes retain the ability to form the Cub(bi) LC phase. They also form hexagonal columnar (Col(h)) LC phases at temperatures higher than those of the Cub(bi) phases. The complex of the monomer and LiBF(4) at the molar ratio of 4:1 exhibits the Cub(bi) and Col(h) phases between -6 to 19 °C and 19 to 56 °C, respectively, on heating. The Cub(bi) LC structure formed by the complex has been successfully preserved by in situ photopolymerization through UV irradiation in the presence of a photoinitiator. The resultant nanostructured film is optically transparent and free-standing. The X-ray analysis of the film confirms the preservation of the self-assembled nanostructure. The polymer film with the Cub(bi) LC nanostructure exhibits higher ionic conductivities than the polymer films obtained by photopolymerization of the complex in the Col(h) and isotropic phases. It is found that the 3D interconnected ionic channels derived from the Cub(bi) phase function as efficient ion-conductive pathways.     

Synthesis, structures and ab initio studies of selenium and tellurium bis(carbodithioates and carbothioates)

A series of selenium and tellurium bis(carbodithioates and carbothioates) were synthesized. X-Ray structure analysis revealed that Se(SSCC(6)H(4)OMe-2)(2), Te(SSCC(6)H(4)OMe-2)(2) and Te(SSCC(6)H(4)Me-4)(2) have trapezoidal-planar configuration of ES(4) (E = Se, Te) and despite the larger atomic radii, the C=S···Te distances in Te(SSCC(6)H(4)OMe-2)(2) are comparable to those in the corresponding selenium derivatives Se(SSCC(6)H(4)OMe-2)(2). Molecular-orbital calculations performed on compounds E(E'SCR)(2) (E = S, Se, Te; E' = O, S; R = Me, Ph, C(6)H(4)OMe-2) showed that the syn-conformers of Se(SSCR)(2) and Te(SSCR)(2) are more stable than the corresponding anti-ones, while, in the case of carbothioic acid derivatives, E(SOCR)(2) showed that their anti-conformers are all more stable than the corresponding syn-ones. Natural bond orbital (NBO) analyses of these dithio-compounds revealed that two types of orbital interactions, n(S(1))→σ*(E-S(2)) and n(O)→σ*(E-S(2)), play a role in the bonding of E[S(2)S(1)CC(6)H(4)OMe-2](2) (E = Se, Te) and the former play a particularly predominant role.     

A risk assessment of human ether-a-go-go-related gene potassium channel inhibition by using lipophilicity and basicity for drug discovery

The blockade of human ether-a-go-go-related gene (hERG) potassium channels is widely regarded as the predominant cause of drug-induced QT prolongation. The correlation analysis between the inhibition of the hERG channel (hERG inhibition) and physicochemical properties was investigated by use of in-house quinolone antibiotics as model compounds. In order to establish a simple prediction model of hERG inhibition, we focused on the comprehensible physicochemical parameters such as lipophilicity (log P) and basicity (pK(a)). At first, the risk associated with increasing log P and pK(a) was examined by statistical analysis. It was demonstrated that the risk associated with increasing log P and pK(a) by one unit, respectively, almost identically increased. Consequently, equal attention should be paid to both parameters on hERG inhibition. Next, a prediction model of hERG inhibition which was represented by log P and pK(a) was investigated. As a result, we built the stepwise discriminant prediction model which took advantage of the risk judgment by zone classification. In conclusion, the impact of log P and pK(a) on hERG inhibition was clarified relatively and quantitatively. The quantitative risk assessment established based on both parameters, was considered to be a practical and useful tool in avoiding hERG inhibition and in the rational drug design for drug discovery, especially in lead optimization. Moreover, we also carried out a trend analysis using a different derivative and demonstrated that both parameters were equally significant for hERG inhibition.     

Several routes to the glassy states in the one component soft core system: revisited by molecular dynamics

Molecular dynamics simulations have been performed to study the glass transition for the soft core system with a pair potential φ(n)(r) = ε(σ∕r)(n) of n = 12. Using the compressibility factor, PV/Nk(B)T=P?(ρ*), its phase diagram can be represented as a function of a reduced density, ρ? = ρ(ε∕k(B)T)(3∕n), where ρ = Nσ(3)∕V. In the present work, NVE relaxations to the glassy or crystalline states starting from the unstable states in the phase diagram have been revisited in details and compared with other processes. Relaxation processes can be characterized by the time dependence of the dynamical compressibility factor (PV/Nk(B)T)(t)?(≡g(ρ(t)*)) on the phase diagram. In some cases, g(ρ(t)*) reached a crystal branch in the phase diagram; however, metastable states are found in many cases. With connecting points for the metastable states in the phase diagram, we can define a glass branch where the dynamics of particles are almost frozen. The structures observed there have common properties characterized as glasses. Although overlaps of glass forming process and nanocrystallization process are observed in some cases, these behaviors are distinguishable to each other by the characteristics of structures. There are several routes to the glass branch and we suggest that all of them are the glass transition.     

Preparation of a colloidal array of NaTaO3 nanoparticles via a confined space synthesis route and its photocatalytic application

The confined space synthesis method has been applied to the preparation of sodium tantalate (NaTaO(3)); hydrothermal reaction of NaOH and Ta(2)O(5) was carried out in the pores of a three-dimensional mesoporous carbon, which was replicated by the colloidal array of silica nanospheres (SNSs) 20 nm in size. This approach led to the formation of a colloidal array of NaTaO(3) nanoparticles 20 nm in size with a surface area of 34 m(2) g(-1). The photocatalytic performance of the colloidal array of NaTaO(3) nanoparticles for overall water splitting under UV irradiation (λ > 200 nm) was evaluated after loading a NiO cocatalyst onto NaTaO(3) samples. The NiO-loaded NaTaO(3) nanoparticles showed photocatalytic activity for overall water splitting more than three times as high as non-structured bulk NaTaO(3) particles.     

POSSIBLE ROLE OF METALLOTHIONEIN IN THE CELLULAR DEFENSE MECHANISM AGAINST UVB IRRADIATION IN NEONATAL HUMAN SKIN FIBROBLASTS

Abstract: The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS-K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40-HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.
The sensitivity of HS-K and NB1RGB cells to UVB irradiation was similar; those of SV40-HSK and Pam 212 cells were two- and six-fold as sensitive to UVB irradiation as HS-K cells, respectively. The HS-K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13-, 7- and 6-fold of those in NB1RGB, SV40-HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation.
NB1RGB cells contained 4–30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 μ M ) or Zn²⁺ (7 μg/mL) treatment were more resistant to UVB irradiation than nontreated ones.
These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in protection against UVB irradiation.     

4-Diazomethylcoumarins and related stable heteroaryldiazomethanes. Thermal conversion into condensed pyrazoles

4-Diazomethyl-substituted coumarins, 1-methyl-2(1H)-quinolinones, 1 -thiocoumarin and their tricyclic analogs were found to be easily cyclized into the corresponding pyrazole isomers condensed with heteroaromatics. Thermodependent feature of these conversions and the remarkably accelerating effect of the alkyl substituent peri to the diazomethyl group were realized. Some other diazomethyl compounds connected with 2-pyridinone, 3-pyrazolone, chromone and 1-thiochromone were prepared, and their stability and thermal properties were compared.     

Measurement of Fluorescence Quantum Yield of Ultraviolet-Absorbing Substance Extracted from Red Alga: Porphyra yezoensis and its Photothermal Spectroscopy

Optical properties of an ultraviolet-absorbing substance (UVAS) extracted from the marine red alga, Porphyra yezoensis, have been investigated. The substance is excited by UV light, and the emitted fluorescence is detected using an intelligent fluorescence detector. The fluorescence of UVAS is weaker by four orders of magnitude than the fluorescence intensity emitted by anthracene in the same optical system. The absorbed energy is apparently not transferred to the photosynthesis process and is believed to be consumed as heat. Using photothermal spectroscopy, a signal is observed indicating that the absorbed photon energy has transferred to the heat. The waveform of the photothermal signal of UVAS is similar to that of quinoxaline, whose fluorescence quantum yield is known to be zero. It is determined that the fluorescence quantum yield and the energy of the triplet state of UVAS are 1.7 ± 0.7 ± 10⁻⁴ and 21000 ± 1000 cm ⁻¹, respectively. The conclusion is that the excited molecules of UVAS decay by passing through the triplet state and dissipate all absorbed energy as heat.     

The birch reduction of heterocyclic compounds. 11. Birch reduction and reductive alkylation of furamides

The Birch reduction-alkylation of some N,N-dialkylfuramides and its application to the useful intermediates for the natural product synthesis are described.