The Ruettimnann’ s method[5] for vitamin K1 synthesis has been improved by usingphase transfer catalyst in Diels-Alder condensation and using mixed trans-cis phytyl chlorideinstead of natural phytol as starting mater...The Ruettimnann’ s method[5] for vitamin K1 synthesis has been improved by usingphase transfer catalyst in Diels-Alder condensation and using mixed trans-cis phytyl chlorideinstead of natural phytol as starting material in the synthesis. The vitamin K1 then obtainedby a retro-Diels-Alder reaction has a cis-trans isomer ratio of 20. 35 to 79. 65 which meets theChinese pharmacopia standard. Phytyl bromide in this case gave vitamin K1 with cis-trans ratio of 26. 30 to 73. 70.展开更多
Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of...Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl- 1-oxaspiro [4, 5] dec -8 - en - 7, 10-dione.展开更多
With the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment substitution on the electrochemical properties of Rhodobac-ter sphaeroides 601 reaction center...With the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment substitution on the electrochemical properties of Rhodobac-ter sphaeroides 601 reaction centers was investigated. Results showed that the charge separation could also be driven by externally electric field, similar to the primary photochemical reaction in purple bacterial reaction center. On the surface of Au electrode, a self-assembled monolayer film (the RC-PDDA-DMSA film) was made up of 2,3-dimercaptosuccinic acid (DMSA), poly-dimeth-yldiallylammonium chloride (PDDA) and reaction center (RC). When square wave voltammetry was used to study the RC-PDDA-DMSA film, four redox pairs in the photochemical reaction of RC were observed by changing frequency. With nonlinear fitting, the standard potential of P/P+ and the corresponding electrode reaction rate constant were determined to be 0.522 V and 13.04 S-1, respectively. It was found that the redox peak at -0.02 V changed greatly when bacteriopheophytin was substituted by plant pheophytin in the reaction center. Further studies indicated that this change resulted from the decrease in electron transfer rate between Bphe7Bphe (Phe7Phe) and QA-/QA after pigment substitution. After investigations of spectra and electrochemical properties of different RCs and comparisons of different function groups of pigments, it was indicated that the phytyl tail, similar to other substituted groups of pheophytin, affected the efficiencies of pigment substitution.展开更多
文摘The Ruettimnann’ s method[5] for vitamin K1 synthesis has been improved by usingphase transfer catalyst in Diels-Alder condensation and using mixed trans-cis phytyl chlorideinstead of natural phytol as starting material in the synthesis. The vitamin K1 then obtainedby a retro-Diels-Alder reaction has a cis-trans isomer ratio of 20. 35 to 79. 65 which meets theChinese pharmacopia standard. Phytyl bromide in this case gave vitamin K1 with cis-trans ratio of 26. 30 to 73. 70.
文摘Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl- 1-oxaspiro [4, 5] dec -8 - en - 7, 10-dione.
基金the National Natural Science Foundation of China (Grant No.29872055 for Chen Z. L., Grant Nos. 39970195 and 29905001 for Zhao J. Q. et al., Grant No.39870161 for Zou Y. L. et al.) and the State Key Basic and Development Plan (G1998010100).
文摘With the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment substitution on the electrochemical properties of Rhodobac-ter sphaeroides 601 reaction centers was investigated. Results showed that the charge separation could also be driven by externally electric field, similar to the primary photochemical reaction in purple bacterial reaction center. On the surface of Au electrode, a self-assembled monolayer film (the RC-PDDA-DMSA film) was made up of 2,3-dimercaptosuccinic acid (DMSA), poly-dimeth-yldiallylammonium chloride (PDDA) and reaction center (RC). When square wave voltammetry was used to study the RC-PDDA-DMSA film, four redox pairs in the photochemical reaction of RC were observed by changing frequency. With nonlinear fitting, the standard potential of P/P+ and the corresponding electrode reaction rate constant were determined to be 0.522 V and 13.04 S-1, respectively. It was found that the redox peak at -0.02 V changed greatly when bacteriopheophytin was substituted by plant pheophytin in the reaction center. Further studies indicated that this change resulted from the decrease in electron transfer rate between Bphe7Bphe (Phe7Phe) and QA-/QA after pigment substitution. After investigations of spectra and electrochemical properties of different RCs and comparisons of different function groups of pigments, it was indicated that the phytyl tail, similar to other substituted groups of pheophytin, affected the efficiencies of pigment substitution.
