Aza-analogues of extended tetrathiafulvalenes

The phosphoramidate-like reaction of 1,3-dithiole derived N-(diethoxyphosphinyl)hydrazones with formyl derivatives of 1,3-dithiole affords the longest aza-analogues of extended tetrathiafulvalenes with a polyenic spacer reported to date. Their structural and electrochemical properties are discussed.     

CCl2自由基与H2O分子反应动力学研究

用213 nm激光光解CCl4产生CCl2自由基，用LP LIF技术测定了室温下基态CCl2自由基与H2O分子的反应速率常数为(5.45±0.95)×10－14 cm3•molecule－1•s－1.在G2MP2理论水平上计算了CCl2＋H2O反应的最低单重态势能面，揭示了插入与加成 消除两种反应机理，得到了三个可能的产物通道:HCl＋HClCO、HCl＋trans ClCOH以及HCl＋cis ClCOH.并用RRKM TST和传统过渡态理论计算了这三个通道的分支比及其温度效应.结果说明在低温下（273 K），插入机理的产物通道的分支比远大于加成 消除机理的产物通道， HCl＋HClCO是主要产物，分支比为77.4％，其次是HCl＋cis ClCOH，分支比为22.6％.而在高温下（3000 K），加成 消除机理的反应通道大于插入机理， HCl＋trans ClCOH分支比为82.3％.     

Novel Chiral Aminophosphine Ligand:Synthesis and Application in Saymmetric Catalytic Hydrogenation Reaction

A new chiral aminophosphine ligand 6,6′-dimethoxy-2,2′-bis(diphenylphosphinoamino)biphenyl(DMBDPPABP) was prepared and its rhodium complex was found to be an effective catalyst for the asymmetric hydrogenation of amidoacrylic acid and its dervatives.The effects of solvent and reaction temperature on enantioselectivity were also studied.     

A New Glycoside and a Novel‐Type Diterpene from Hemerocallis fulva (L.) L.

The CHCl₃ extract of dried roots of Hemerocallis fulva (L.) L. afforded a novel diterpene named hemerocallal A ( 1 ), which is the second reported naturally occurring diterpene with a trans‐bicyclo[5.1.0]octane system. The BuOH extract afforded a new glycoside named hemerocalloside ( 2 ). Their structures were established on the basis of spectroscopic and chemical studies.     

A DFT study on the double bond migration of butene catalyzed by ionic pair of 1-ethyl-3-methyl-imidazolium fluoride

The double bond migration of butene catalyzed by 1-ethyl-3-methyl-imidazolium fluoride (EmimF) has been studied using quantum chemical method. The geometries of reactant, transition state and product for the isomerization have been optimized by density functional theory (DFT) at the B3PW91/6-31G(d,p), 6-311++G(d,p) and aug-cc-PVDZ levels. The computed results show that the 4-H atom on imidazole ring of EmimF has a good catalytic activity to the double bond migration of butene and the catalytic reaction of 1-butene to 2-butene is a synergetic and elementary process. The apparent activation energy of isomerization is about 197 kJ/mol.     

Systematic investigation of the hydrothermal syntheses of Pr(III)-PDA (PDA = pyridine-2,6-dicarboxylate anion) metal-organic frameworks

A series of novel two-dimensional (2D) and three-dimensional (3D) praseodymium coordination polymers, namely, {[Pr3(PDA)4(HPDA)(H2O)8] x 8H2O}n (2), {[Pr2(PDA)3(H2O)3] x H2O}n (3), {[Pr(PDA)(H2O)4] x ClO4}n (4), and { [Pr2(PDA)2(H2O)5SO4] x 2H2O}n (5) (PDA = pyridine-2,6-dicarboxylic anion), was designed and synthesized under hydrothermal conditions. Complexes 1-3 (chainlike polymer, {[Pr(PDA)(HPDA)(H2O)2] x 4H2O}n (1) was also obtained independently by us, although it has been reported recently by Ghosh et al.) were fabricated successfully by simply tuning the Pr/PDA ratio and exhibited various and intriguing topological structures from a 1D chain to a 3D network. While the synthetic strategy of 5 was triggered and further performed only after 1 was structurally characterized. The complexes were characterized by X-ray single-crystal determination, spectroscopic, and variable-temperature magnetic susceptibility analyses. In complex 2 an unusual nanosized square motif as a building block constructed by eight Pr ions was further assembled into a highly ordered 2D grid compound. In complex 3 the decanuclear Pr metal-based structure as a repeat unit interpenetrated to form a novel 3D polymer. Complex 4 was a 3D network polymer fabricated through a hexanuclear Pr ring as a building block, and ClO4- anions as guests were trapped in the cavity. In complex 5 six Pr atoms, two SO4(2-) anions, and carboxylic oxygen bridges constructed an intriguing rectangle structure as a repeat unit in the grid to form a 2D coordination polymer in which the unique bi-bidentate coordination mode of SO4(2-) anion was observed.     

A 3-D noninterpenetrating diamondoid network of a decanuclear copper(I) complex

The solvothermal reaction of CuCl(2).2H(2)O with pyridine-4-thiol and ethanol yielded a novel photoluminescent 3-D polymeric complex with an interesting decorated diamondoid network that is constructed of decanuclear copper(I) cluster units and mu(4)-Cl ligands. The in situ generation of CuSO(4).5H(2)O implies the spontaneous occurrence of desulfurization and redox reactions in the present system.     

Adsorption separation of terpene lactones from Ginkgo biloba L. extract using glass fiber membranes modified with octadecyltrichlorosilane

In this study porous glass fiber membranes were modified by reaction with octadecyl-trichlorosilane to form C18 hydrophobic membranes. The contact angle and the CH2 vibration bands at 2855 and 2920 cm(-1) found by FTIR measurements verified the successful immobilization of C18 groups on the glass fiber membranes. The resulting C18 hydrophobic membranes were used to adsorb terpene lactones from crude Ginkgo biloba L. extracts. In batch adsorption processes, the modified C18 membranes exhibited a better adsorption performance than commercial C18 solid phase extraction adsorbents. Different desorption solvents were tested and ethyl acetate was found to preferentially desorb terpene lactones from the modified C18 membranes. In flow adsorption experiments at 1 mL/min, terpene lactone contents higher than 6 wt% (the standardized content) could be achieved in the elution step using ethyl acetate.     

Total synthesis of crotophorbolone

As a natural diterpenoid, crotophorbolone possesses a challenging trans,trans-5/7/6 framework decorated with six contiguous stereogenic centers and is structurally and biogenetically related to tigliane-type diterpenoids with intriguing bioactivities such as phorbol and prostratin. Based on the convergent strategy, we completed an eighteen-step total synthesis of crotophorbolone starting from (−)-carvone and (+)-dimethyl-2,3-O-isopropylidene-l-tartrate. The key elements of the synthesis involve expedient installation of the six-membered ring and the five-membered ring with multiple functional groups at an early stage, cyclization of the seven-membered ring through alkenylation of the ketone between the five-membered ring and the six-membered ring, functional group-sensitive ring-closing metathesis and final selective introduction of hydroxyls at C₂₀ and C₄.

Convergent total synthesis of crotophorbolone was accomplished in 18 longest linear steps. Observation of unexpected thermodynamic stability of a cis,trans-5/7/6 tricycle would benefit synthetic design of tigliane- and daphnane-related diterpenoids.     

Reduction of 4-nitrophenol catalyzed by nitroreductase

The reduction of 4-nitrophenol catalyzed by nitroreductase in the presence of NADH was investigated in this paper.4-Amino- phenol and 4-bydroxylamino-phenol were found in the reductive products.The relationship between reaction time and the reductive ratio were studied.The similar reducing ratios of 4-nitrophenol were obtained under aerobic and anaerobic conditions.The results indicated that an oxygen-insensitive reaction was proceeded in the reduction of 4-nitrophenol and nitroreductase was an oxygen- insensitive enzyme.The reductive products of 4-nitrophenol were determined by HPLC and MS.