Neo‐Fused Hexaphyrin: A Molecular Puzzle Containing an N‐Linked Pentaphyrin

The first neo‐confused hexaphyrin(1.1.1.1.1.0) was synthesized by oxidative ring closure of a hexapyrrane bearing two terminal “confused” pyrroles. The new compound displays a folded conformation with a short interpyrrolic C???N distance of 3.102 Å, and thus it readily underwent ring fusion to afford a neo‐fused hexaphyrin with an unprecedented 5,5,5,7‐tetracyclic ring structure. Furthermore, coordination of Cu^II triggered a ring opening/contracting reaction to afford a Cu^II complex of an N‐linked pentaphyrin derivative. The roles of reactive N? C bonds in the porphyrinoid macrocycles were demonstrated.     

A Feruloyl Esterase (FAE) Characterized by Relatively High Thermostability from the Edible Mushroom Russula virescens

A monomeric feruloyl esterase (FAE) with a molecular mass of 62 kDa was acquired from fresh fruiting bodies of the edible mushroom Russula virescens. The isolation procedure involved ion exchange chromatography on CM-cellulose, Q-Sepharose, and SP-Sepharose and finally fast protein liquid chromatography–gel filtration on Superdex 75. Two amino acid sequences were obtained after tryptic digestion, and they both showed some homology with the esterase of some fungi. Maximal activity was observed at pH 5.0 and at 50 °C. The enzyme displayed relatively high thermostability as evidenced by over 70 % residual activity at 70 °C and about 34 % residual activity at 80 °C. The K _m and V _max for this enzyme on methyl ferulate were 0.19 mM and 1.65 U/mg proteins, respectively. The purified FAE prefers methyl ferulate over methyl caffeate and is least active on methyl p-coumarate. The FAE activity was not significantly affected by the presence of cations such as Mn²⁺, Ca²⁺, Cd²⁺, Zn²⁺, Mg²⁺, Cu²⁺, and K⁺ ions but inhibited by Al³⁺, Hg²⁺, Fe²⁺, and Pb²⁺ ions at a tested concentration of 2. 5 mM.     

Ferric Ion Driven Assembly of Catalase-like Supramolecular Photosensitizing Nanozymes for Combating Hypoxic Tumors

A facile approach to assemble catalase-like photosensitizing nanozymes with a self-oxygen-supplying ability was developed. The process involved Fe³⁺-driven self-assembly of fluorenylmethyloxycarbonyl (Fmoc)-protected amino acids. By adding a zinc(II) phthalocyanine-based photosensitizer (ZnPc) and the hypoxia-inducible factor 1 (HIF-1) inhibitor acriflavine (ACF) during the Fe³⁺-promoted self-assembly of Fmoc-protected cysteine (Fmoc-Cys), the nanovesicles Fmoc-Cys/Fe@Pc and Fmoc-Cys/Fe@Pc/ACF were prepared, which could be disassembled intracellularly. The released Fe³⁺ could catalyze the transformation of H₂O₂ enriched in cancer cells to oxygen efficiently, thereby ameliorating the hypoxic condition and promoting the photosensitizing activity of the released ZnPc. With an additional therapeutic component, Fmoc-Cys/Fe@Pc/ACF exhibited higher in vitro and in vivo photodynamic activities than Fmoc-Cys/Fe@Pc, demonstrating the synergistic effect of ZnPc and ACF.     

Remote regioselective organocatalytic asymmetric [3+2] cycloaddition of N-2,2,2-trifluoroethyl isatin ketimines with cyclic 2,4-dienones

An organocatalytic asymmetric [3+2] cycloaddition of trifluoromethyl-containing azomethine ylides with cyclic 2,4-dienones was developed.The process enables efficient incorporation of CF3 groups into functionalized spiro [pyrro lid in-3,2'-oxindoles] in high yields with good to excellent enantio-and diastereoselectivities.     

STRUCTURE, MOLECULAR WEIGHT AND BIOACTIVITIES OF (1→3)-β-D- GLUCANS AND ITS SULFATED DERIVATIVES FROM FOUR KINDS OF LENTINUS EDODES

Lentinan samples, (1→3)-β-D-glucans containing 4.6-15.2 wt% proteins, coded as L-I1, L-I2, L-I3 and L-I4 (L-I)were isolated from four kinds of Lentinus edodes. These glucans were treated with acetone to remove the protein in order to obtain free protein glucans coded as LNP-I1, LNP-I2, LNP-I3 and LNP-I4 (LNP-I). The free-protein polysaccharides were sulfated to give derivatives (S-LNP-I) with degree of substitution (DS) from 0.4-0.8. The structural features and weight- average molecular weight (Mw) of the samples were investigated by using infrared spectroscopy, elemental analysis,13C-NMR, size exclusion chromatography combined with laser light scattering (SEC-LLS) and viscometry. The effects of structure and conformation of the polysaccharides on antitumor activities were assayed in vivo (Sarcoma 180 solid tumors)and in vitro (Sarcoma 180, HL-60, MCF-7 and Vero tumors). The results indicated that the predominant species of the samples L-I and LNP-I in 0.2 mol/L NaCl aqueous solution existed as triple-helical chains with high rigidity and in dimethyl sulfoxide (DMSO) as single-flexible chains. Interestingly, the antitumor activities of LNP-I are lower than those of the native glucans (L-I), whereas their sulfated derivatives have higher inhibition ratio against Sarcoma 180 than LNP-I. The results reveal that the binding of protein, sulfated modification and the triple helix conformation are important factors in the enhancement of the antitumor activities of polysaccharides on the whole.     

Template‐Free Hydrothermal Synthesis of Mesoporous MgO Nanostructures and Their Applications in Water Treatment

The controlled synthesis of Mg(OH)₂ nanowires and microflowers composed of nanoplates was successfully achieved by a template‐free hydrothermal synthetic method. It was found that the reaction medium played a crucial role in the morphological control of the precursor nanostructures. The high polarity of water molecules favored the polar growth of the precursor, resulting in the formation of nanowires with a diameter of 80 nm, whereas a mixed water/ethanol medium with a lower degree of polarity led to the formation of microflowers. Moreover, mesoporous MgO nanostructures could be obtained by further annealing these as‐prepared precursors in air at 500 °C for 2 h. During thermal treatment, the wire‐ and flower‐like morphologies were retained. Porosity formation was due to thermal decomposition of Mg(OH)₂ and release of H₂O. Both the mesoporous MgO nanowires and microflowers showed superior ability of adsorbing the organic dye methyl orange, and thus they are promising candidates for polluted water treatment.     

Advances in ultra-high load polymer-supported peptide synthesis with phenolic supports: 2. Use of ‘hydrazinolysis-hplc’ to check for racemization on c-terminal amino acid loading and to determine peptide homogeneity during synthesis with selectively labile c-terminal anchoring linkages

2, 4-Dinitrophenyl-L-phenylalanine has been coupled to L-, D-, and DL-amino acid phenyl esters pendant upon a polymer matrix. The esters had been prepared by di-isopropylcarbodiimide-mediated condensation, catalyzed by 4-dimethylaminopyridine. Reverse phase high pressure liquid chromatography (HPLC), using elution solvents consisting of 10 vol.-% trifluoroacetic acid in water/acetonitrile mixtures, has been used to investigate the 2,4-dinitrophenyl L-L and L-D dipeptide mixtures obtained on hydrazinolysis of each of the dipeptide-matrix assemblies. ‘Hydrazinolysis-HPLC’ has been used also to determine intermediate peptide homogeneity in ultra-high load solid (gel) phase synthesis with Boc amino acids. Cross-linked poly(N-[2-(4-hydroxyphenyl)ethyl]acrylamide) and two derived polymers incorporating spacer groups have been used as supports. The spacer groups made possible peptide C-terminal attachment by either HF-labile benzyl ester or HF-labile cyclohexyl ester bonds, while still incorporating the phenolic ester linkage susceptible to rapid hydrazinolytic scission.     

Empirical pseudopotential band structure parameters of 4H-SiC using a genetic algorithm fitting routine

In this paper, the viability of using a genetic algorithm to find band structure parameters for empirical pseudopotential method (EPM) calculations is demonstrated by applying a genetic algorithm to find the EPM parameters for 4H-SiC. The form of the pseudopotential for 4H-SiC and the 19 form factors found by the genetic algorithm to fit the band structure to experimentally measured indirect energy gap and direct optical gaps are given. In addition, the effective masses for the conduction band minimum are extracted from the calculated band structure. It is shown that the genetic algorithm provides an effective, automated way to find parameters that give reasonably good fits to both the band gaps and the effective masses simultaneously.     

转动分辨的H2+ (X2Σ+g , v+=0-18)真空紫外脉冲场电离光电子谱

测量了氢气离子转动分辨的真空紫外脉冲场电离光电子谱．涵盖了15.30?18.09 eV能量范围内的H2+(X2§+g , v+=0?18,N+=0?5)?H2(X1§+g , v00=0, J00=0?4)的电离跃迁． 通过基于Buckingham-Orr-Sichel(BOS)模型的光谱拟合和对氢气离子振动带H2+(X2§+g ,v+=0?18)的转动光谱的分析, 发现实验上只观察到对应于￠N=N+-J00=0,§2的转动跃迁． 振动量子数v+ 越高，￠N=0的转动跃迁越占主导地位， 而转动谱线强度受邻     

Agitation-free multiphoton microscopy of oblique planes

The scanning two-photon fluorescence microscope produces optically sectioned images from the focal plane. It is sometimes desirable to acquire images from other planes of the specimen that are inclined with respect to the focal plane. In this Letter, we discuss the issues concerned with acquiring such images together with the effects of the inclination angle on image resolution and sectioning strength. To obtain images from oblique planes at high speed, a two-photon system was built wherein a novel optical system is used to provide aberration-free scanning.