The Influence of Temperature on Ethene Diffusion in H[Al]ZSM-5 Studied by Molecular Dynamics

Molecular dynamics(MD) simulation of ethene diffusion in the lattice of H[Al]ZSM-5 was performed at the temperature ranging from 300 K to 700 K. The calculated diffusion coefficients increase with the temperature from 2.60×10-9 m2/s at 300 K to 12.78×10-9 m2/s at 700 K. The Arrhenius plot gives an activation energy of 6.31 kJ/mol. The anisotropy of the diffusion process was examined.     

Interaction between sodium tanshinone IIA sulfonate and the adriamycin semiquinone free radical: A possible mechanism for antagonizing adriamycin-induced cardiotoxity

Adriamycin (ADR) is a powerful and widely used antitumor drug, but its dose dependent cardiotoxicity limits its application. This side effect is believed to be caused by the adriamycin semiquinone free radical (ASFR). The primary focus of this work is to test effects of sodium tanshinone IIA sulfonate (STS) on ASFR and adriamycin–induced lipid peroxidation. It was found that ADR, whether in the system of heart homogenate, heart mitochondria or heart submitochondria, with NADH as the substrate or in xanthine/xanthine oxidase under anaerobic conditions, all produced ASFR rapidly. STS was shown to effectively scavenge ASFR in all these systems and postpone the appearance of ASFR. The delayed time was proportional to the amount of STS. Under aerobic conditions, ASFR could be oxidized to generate oxygen free radicals. STS could not scavenge these oxygen free radicals, but it could effectively scavenge lipid free radicals generated from membrane lipid peroxidation of heart mitochondria. STS could significantly reduce mitochondrial swelling and lipid peroxidation induced by ADR. Animal experiments show that treatment of STS could inhibit endogenous lipid peroxidation caused by ADR. Here, a protective mechanism of STS is suggested that STS can rapidly and univalently oxidize ASFR, causing the cycle of adriamycin between its quinone form and semiquinone form and inhibiting the accumulation of ASFR. Under aerobic condition, STS can protect heart mitochondria by scavenging lipid free radicals generated from adriamycin-induced mitochondrial lipid peroxidation. This investigation shows that STS may be a physiological drug to antagonize the cardiotoxicity of ADR.     

α′-苯磺酰基-α,β-不饱和酮与开链二烯烃的不对称催化环加成反应

在手性金属钛催化剂存在下 ,研究了α′ 苯磺酰基 α ,β 不饱和酮与开链二烯的不对称催化环加成反应 ,讨论了α′ 苯磺酰基 α ,β 不饱和酮与开链二烯的反应活性和对映选择性 ,以高的收率和光学纯度合成了环己烯衍生物 ,并对部分产物的构型进行了鉴定     

4-氨基-L-赤-生物蝶呤的全合成研究

报道了两种合成4-氨基-L-赤-生物蝶呤(2)的方法：(1)以2-N-1',2'-O-三乙酰基-L-赤-生物蝶呤(3)为原料,经4-O-甲基化、氨解而得2;(2)为4-氨基-L-赤-生物蝶呤(2)的“一锅法”全合成,即通过保护了的5-脱氧-L-阿拉伯糖(9)和2,4,5,6,-四氨基嘧啶缩合,经碘氧化得到二乙酰氨基生物蝶呤(11),11的进一步乙酰化后即可经硅胶柱层析纯化,获得四乙酰基氨基生物蝶呤(12),用NH3-H2O/MeOH皂化12即得2。5-脱氧-L-阿拉伯糖(7)由L-鼠李糖二乙基缩硫醛衍生物(5)制得,这样由5制备2的总收率为17%。     

A Highly diastereoselective synthesis of (1R)-(+)-camphor-based chiral allenes and their asymmetric hydroboration-oxidation reactions

Synthesis of camphor derived chiral allenes and their hydroboration-oxidation reactions are described. Reaction of (1R)-(+)-camphor with alkynyllithium followed by the reduction of the resulted propargyl alcohol derivatives using AlH3 furnished chiral allenes 2a-g in excellent yields with high diastereoselectivity. Reduction of the propargyl alcohols with aluminum hydride proceeded through selective intermolecular anti-addition of hydride ion. The stereochemistry of the chiral allenes 2 was assigned based on lanthanide shift studies and chemical correlations. Diastereoselectivity was observed in the hydroboration-oxidation of 2 which produced a mixture of (E,R) and (E,S) stereoisomers in a ratio of 6:1 to 18:1.     

Toward the molecular flashlight: preparation,properties, and photophysics of a hypericin-luciferin tethered molecule

The synthesis of a molecule containing hypericin and luciferin moieties joined by a tether is reported. The light-induced (in vitro) antiviral activity as well as the photophysical properties of this new compound are measured and compared with those of the parent compounds, hypericin and pseudohypericin. This tethered molecule exhibits excited-state behavior that is very similar to that of its parent compounds and antiviral activity that is identical, within experimental error, to that of its more closely related parent compound, pseudohypericin. The implications for a photodynamic therapy that is independent of external light sources are discussed.     

Synthesis,cytotoxicity, apoptosis and cell cycle arrest of a monoruthenium(II)-substituted Dawson polyoxotungstate

By 5-h reaction of cis-[Ru^IICl₂(DMSO)₄] (M2) with K₁₀[α₂-P₂W₁₇O₆₁] (M3) in ice-cooled, HCl-acidic aqueous solution, a water-soluble 1:2-type diamagnetic ruthenium(II) complex of formula K₁₈[Ru^II(DMSO)₂(P₂W₁₇O₆₁)₂]·35H₂O (M1) was unexpectedly obtained as an analytically pure, homogeneous tan-colored solid, in which two DMSO ligands are coordinated to the ruthenium(II) atom. The cytotoxic potential of the complex was tested on C33A, DLD-1, and HepG-2 cancer cells and human normal embryonic lung fibroblasts cell MRC-5; the viability of the treated cells was evaluated by MTT assay. The mode of cell death was assessed by morphological study of DNA damage and apoptosis assays. Compound M1 induced cell death in a dose-dependent manner, and the mode of cell death was essentially apoptosis though necrosis was also noticed. Cell cycle analysis by flow cytometry indicated that M1 caused cell cycle arrest and accumulated cells in S phase.     

Logic‐Gate‐Actuated DNA‐Controlled Receptor Assembly for the Programmable Modulation of Cellular Signal Transduction

Programming cells to sense multiple inputs and activate cellular signal transduction cascades is of great interest. Although this goal has been achieved through the engineering of genetic circuits using synthetic biology tools, a nongenetic and generic approach remains highly demanded. Herein, we present an aptamer‐controlled logic receptor assembly for modulating cellular signal transduction. Aptamers were engineered as “robotic arms” to capture target receptors (c‐Met and CD71) and a DNA logic assembly functioned as a computer processor to handle multiple inputs. As a result, the DNA assembly brings c‐Met and CD71 into close proximity, thus interfering with the ligand–receptor interactions of c‐Met and inhibiting its functions. Using this principle, a set of logic gates was created that respond to DNA strands or light irradiation, modulating the c‐Met/HGF signal pathways. This simple modular design provides a robust chemical tool for modulating cellular signal transduction.     

A Diruthenium‐Based Mixed Spin Complex Ru25+(S=1/2)‐CN‐Ru25+(S=3/2)

An unusual tetra‐nuclear linear cyanido‐bridged complex [Ru₂(μ‐ap)₄‐CN‐Ru₂(μ‐ap)₄](BPh₄) ( 1 ) (ap=2‐anilinopyridinate) has been synthesized and well characterized. The crystallographic data, magnetic measurement, IR, EPR and theoretical calculation results demonstrate that complex 1 is the first example of mixed spin Ru₂⁵⁺‐based complex with uncommon electronic configurations of S=1/2 for the cyanido‐C bound Ru₂⁵⁺ and S=3/2 for the cyanido‐N bound Ru₂⁵⁺. This phenomenon can be understood by the theoretical calculation results that from the precursor Ru₂(μ‐ap)₄(CN) (S=3/2) to complex 1 the energy gap between π* and δ* orbitals of the cyanido‐C bound Ru₂⁵⁺ core increases from 0.57 to 1.61 eV due to the enhancement of asymmetrical π back‐bonding effect, but that of the cyanido‐N bound Ru₂⁵⁺ core is essential identical (0.56 eV). Besides, the analysis of UV/Vis‐NIR spectra suggests that there exists metal to metal charge transfer (MMCT) from the cyanido‐N bound Ru₂⁵⁺ (S=3/2) to the cyanido‐C bound Ru₂⁵⁺ (S=1/2), supported by the TDDFT calculations.