Occurrence of erythro-docosasphinga-4,8-dienine,as an ester,in anemonia sulcata.

A new sphingosine derivative was isolated from A.sulcata; ¹H and ¹³C NMR spectra are described.     

Enzymatic Synthesis of Noncanonical α-Amino Acids Containing γ-Tertiary Alcohols

Noncanonical amino acids (ncAAs) containing tertiary alcohols are valuable as precursors of natural products and active pharmaceutical ingredients. However, the assembly of such ncAA scaffolds from simple material by C−C bond formation remains a challenging task due to the presence of multiple stereocenters and large steric hindrance. In this study, we present a novel solution to this problem through highly selective enzymatic decarboxylative aldol addition. This method allows for the streamlined assembly of multifunctionalized ncAAs with γ-tertiary alcohols from readily available materials, such as _L-aspartatic acid and isatins, vicinal diones and keto esters. The modularity of electrophiles furnished four classes of ncAAs with decent efficiency as well as excellent site and stereocontrol. Computational modeling was employed to gain detailed insight into the catalytic mechanism and to provide a rationale for the observed selectivities. The method offers a single-step approach to producing multifunctionalized ncAAs, which can be directly utilized in peptide synthesis and bioactivity assessment.     

Inclusion complexes phenanthrene-β-cyclodextrin and their interactions with aliphatic amines

In the present work the formation constant of phenanthrene- β-cyclodextrin (Ph-β-CD) complexes in water and in H₂O-DMSO(Dimethyl sulfoxide)20 % were calculated. Interactions between the complexes and two aliphatic amines: diethylamine (DEA) and triethylamine (TEA) were also studied. The characteristies of the amine, in relation to the solvent used, were seen to be very important.     

416 - Surface and/or donnan potentials at the thylakoid membrane?: Part III. Experimental results for a 1 : 1 electrolyte

The light-induced change of the transmembrane potential of spinach thylakoids is measured via the electrochromic absorption change, which is corrected for additionally occurring light-scattering changes. The potential is negligible for KCl concentrations > 5 × 10⁻² M, which suggests the interpretation as a generalized Donnan potential with constant internal volume. Accordingly, the variation of the dark volume with KCl concentration, which does occur and is measured by radioactive labelling of the water, cannot be described by an osmotic equilibrium with freely variable volume.     

415 - Surface and/or Donnan potentials at the thylakoid membrane?: Part II. Calculation of light-induced surface potential changes and corresponding ion movement for a 1 : 1 electrolyte

The surface potential at the inner side of the thylakoid membrane in the dark and in the light state is calculated using the simple Gouy-Chapman theory, together with modifications to allow for proton binding to the surface. The corresponding transmembrane potential change and the ion transport, necessary for ion redistribution in the diffuse double layer, are formulated. the steady-state generalized Donnan potential is shown to be negligible. Finally, the surface potential representation is compared with the Donnan potential representation, given in the preceding paper. On the basis of the formula derived, measurements are discussed which will help to decide between the different concepts.     

Structural elucidation and NMR assignments of two new pyrrolosesquiterpenes from Streptomyces sp. Hd7‐21

Two new pyrrolosesquiterpenes were isolated from cultures of the soil actinomycete Streptomyces sp. Hd7‐21. The structures of these compounds were elucidated by extensive spectroscopic analyses including MS and 1D and 2D NMR data. Their cytotoxic activity against a panel of human cancer cell lines were biologically evaluated. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermal effect on microstructure vibration of SiO2 thin films

The microstructure of amorphous SiO₂ thin film is a random network structure in which a large amount of [SiO₄] is interconnected with a specific SiOSi bond angle. The SiO₂ thin films used in this paper were prepared by ion beam sputtering and electron beam evaporation deposition techniques. Two-dimensional correlation spectroscopy analysis techniques were used in this study. By measuring the infrared temperature spectrum, we obtained the two-dimensional correlation synchronous spectrum and asynchronous spectrum, and decomposed the in-phase and out-phase asymmetric stretching vibration characteristics of SiOSi. As the temperature increases, the spectral transmittance of the vibrating peak decreases, and the relative change of in-phase asymmetric stretching vibration absorption peak is higher than that of the out-phase asymmetric stretching vibration absorption peak.     

联二噻吩稠合的近红外BODIPY染料的合成与光谱性质

以叠氮乙酸乙酯和联二噻吩甲醛为原料,合成了联二噻吩并吡咯单体,之后在酸催化下与4-N,N-二甲基氨基苯甲醛缩合并与三氟化硼配位,得到一个新型的BODIPY染料SY。采用¹H NMR、质谱以及元素分析对其结构进行了表征。化合物SY在二氯甲烷中的最大吸收和发射波长分别为654和689 nm;采用荧光光谱滴定方法研究了它对pH值的响应,酸性条件下N,N-二甲基苯氨基团发生质子化,抑制了光诱导电子转移对BODIPY母体的荧光淬灭,其溶液的荧光显著增强,染料SY可以作为近红外的pH值荧光探针。