Homohelicity induction of propylene-linked zinc bilinone dimers by complexation with chiral amine and α-amino esters. Preorganization of structurally coupled homohelical subunits

Homohelicity induction of a series of propylene-linked zinc bilinone (ZnBL; linear tetrapyrrople-zinc(II) complex) dimers upon complexation with chiral amine and α-amino esters was investigated. Introduction of substituents such as dimethyl and diisobutyl to the central carbon of the propylene spacer gave rise to stabilization of the homohelical (PP and MM) conformers rather than the heterohelical (PM) conformer. As bulkiness of the substituent increased, stability of the homohelical conformers was raised. The preorganization of the homohelical structures led to significantly amplified homohelicity induction upon complexation with chiral amine and α-amino esters.     

Synthesis of polystyrene latex with amphoteric surfactant and its characterization

An emulsion polymerization of styrene in the presence of an amphoteric surfactant; N,N-dimethyl-n-laurylbetaine (LNB) was carried out at pH 7.0. The polymerization rate and the concentration of the latex particle were proportional to the LNB concentration of 0.6 power. The latex particle sizes became smaller with increasing concentrations of LNB. The molecular weights of polystyrene latices increased with the concentration of LNB. The zeta-potentials of latex particles were significantly dependent on the pH, and showed the existence of an isoelectric point.     

Extraction equilibrium of palladium(II) with 2-methyl-8-quinolinol into supercritical carbon dioxide fluid

The present study is concerned with the extraction behavior and equilibrium of Pd(II) with 2-methyl-8-quinolinol (HMQ) into supercritical fluid CO(2) (SF-CO(2)). Pd(II)-HMQ complex extracted from a weakly acidic solution (pH 2-3) into SF-CO(2) was determined to be Pd(MQ)(2) on the basis of a slope analysis. The extraction constant K(ex,SF) (=[Pd(MQ)(2)](SF)[H(+)](2)[Cl(-)](4)[PdCl(4)(2-)](-1)[HMQ](-2)) was determined to be 10(4.3+/-0.2) at 8.5 MPa, 45 degrees C and I=0.4 M (H,Na)Cl (1 M=1 mol dm(-3)). The distribution behavior of HMQ between an aqueous and a SF-CO(2) phase was examined so as to discuss quantitatively the extraction equilibrium. The extraction constant (K(ex,Cy)) of Pd(II) with HMQ into cyclohexane with a similar polarity to SF-CO(2) was determined and the K(ex,SF) was compared with the K(ex,Cy). Pd(II) at the concentration range of 10(-5)-10(-4) M in the aqueous solution (pH<3) containing relatively high concentration of chloride ion was found to be extracted efficiently by the SF-CO(2) extraction.     

A brief study of the supercritical fluid chromatographic behavior of lanthanide β-diketonates

The chromatographic behaviors of lanthanide chelates of acetylacetone (ACAC), trifluoroacetylacetone (TFA), thenoyltrifluoroacetone (TTA), dipivaloylmethane (THD), 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (FOD), and the thenoyltrifluoroacetonepyridine (TTA·Py) adduct were investigated using packed column supercritical fluid chromatography. Mobile phases consisting of neat and alcohol modified CO₂ were used with a phenyl packed stationary phase. Lanthanide complexes of ACAC, THD, and FOD were shown to have better chromatographic performance compared to the corresponding chelates with TFA, TTA, and TTA·Py. In particular, TTA complexes such as Eu(TTA)₃ showed characteristic thermal decomposition in the mobile phase at elevated temperature. In addition, retention behavior was found to be a temperature dependent function of volatility and solubility for all chelates studied.     

Monolayer properties of mixtures of poly(n-stearyl methacrylate), poly(n-lauryl methacrylate), and their corresponding copolymers

The monolayer properties of poly(n-stearyl methacrylate), poly(n-lauryl methacrylate), and their mixtures at various ratios of the two polymers have been studied from the measurements of their surface pressure–area isotherms at air–water interface. The monolayer properties of their mixtures have been compared with those of their corresponding copolymers. The results show that the isotherms of the mixed monolayers have two break points at higher pressures than that of poly(n-lauryl methacrylate). This suggests that the mixtures may form more stable films that consist of separate phases of the two homopolymers, although each phase may contain a small amount of the other. The isotherms of the copolymer monolayers indicate a phase transition from liquid condensed to solid film between 50 segment mole % and 70% poly(n-stearyl methacrylate). The monclayer of these copolymers has properties that differ from those of the corresponding mixtures of two pure homopolymers and is more compatible than the mixtures of pure homopolymers.     

Stratum corneum lipid abnormalities in UVB-irradiated skin

Stratum corneum (SC) lipids are of particular importance in maintaining the permeability barrier function. Although many studies have demonstrated that UVB irradiation of mammalian skin reduces barrier function, the responsible alterations in SC lipid profiles are not known. In this study, we investigated both compositional and morphological alterations in SC lipids with the development of barrier abnormalities caused by daily UVB irradiation in hairless rat skin. The UVB irradiation of suberythemal doses (0.5 minimal erythema dose) significantly increased transepidermal water loss (TEWL) relative to nonirradiated control, indicating a diminished barrier function. Under these conditions, the total amounts of major SC lipid species (ceramides, cholesterol, free fatty acids) in UVB-irradiated SC did not differ from those in nonirradiated SC. However, electron microscopic observations revealed marked abnormalities in the intercellular domains of UVB-irradiated SC, where naturally occurring intercellular multilamellar structures were often absent and leaving the area with the appearance of an empty space. Moreover, in UVB-irradiated SC, individual corneocytes often showed small amounts of intercellular deposition product with abnormal lamellar structure, where lamellar body sphingomyelinase activity was present. These observations demonstrated a partial failure of lamellar body secretion in UVB-irradiated SC and suggested that a defect in the secretion of lamellar body-derived lipids and enzymes to SC intercellular space is, at least in part, responsible for the observed abnormal intercellular structure and barrier disruption.     

Isolation and characterization of bioactive metabolites from marine-derived filamentous fungi collected from tropical and sub-tropical coral reefs

Two new compounds, paecilospirone (1) and phomopsidin (2), and seven known compounds, chaetoglobosin A (3), griseofulvin (4), fusarielin A (5), fusapyrone (6), deoxyfusapyrone (7), and verrucarins J (8) and L acetate (9), have been isolated and characterized from marine-derived fungi collected in tropical and sub-tropical coral reef environments. The utility of marine-derived fungi as a source of bioactive secondary metabolites is discussed.