Copolymerization of 1,6-anhydro-ß-D-galactopyranose and 1,6-anhydro-ß-D-mannopyranose derivatives

1,6-Anhydro-2,3,4-tri-O-(p-methylbenzyl)-ß-D -galactopyranose (TXGal,M₁) has been copolymerized with 1,6-anhydro-2,3,4-tri-O-benzyl-ß-D -mannopyranose (TBMan,M₂), the products characterized by NMR, specific rotation, and viscosity, and the reactivity ratios calculated. The reactivity ratios r₁ = 0.37 ± 0.15 and r₂ = 38 ± 4 indicate that the anhydromannose derivative is about 100 times as reactive as that of anhydrogalactose. A comparison of glucose, mannose, and galactose copolymerizations suggests that the reactivity differences of the three propagating cations are comparatively small and the reactivity differences of the monomers large. This result is consistent with a mechanism proposed earlier. Methyl substitution on the aromatic rings of the p-xylyl groups inhibits the initiation process significantly relative to benzyl, but propagation only slightly.     

A Novel Dimeric Coumarin from Clausena lenis

A novel dimeric coumarin (1), a dimeric of seselin named diseselin A, was isolated from the aerial part of Clausena lenis. The structure was elucidated based on the MS, 1D and 2D NMR data.     

Dependence of molecular recognition of fullerene derivative on the adlayer structure of zinc octaethylporphyrin formed on Au(100) surface

Adlayers of ZnOEP were prepared on reconstructed Au(100)-(hex) and unreconstructed Au(100)-(1 x 1) surfaces by immersing into a benzene solution containing ZnOEP molecules, and the adlayer structures were characterized by scanning tunneling microscopy (STM). A hexagonally arranged ZnOEP array was formed on an Au(100)-(hex) surface, whereas a rectangularly arranged ZnOEP array was found on an Au(100)-(1 x 1) surface. The adlayer structure of ZnOEP was dependent upon the underlying Au atomic arrangements. Furthermore, an investigation of the spuramolecular assembly for these modified surfaces was carried out by using an open-cage C(60) derivative (opened C(60)). A supramolecular assembled adlayer with a 1:1 composition of opened C(60)/ZnOEP was formed on Au(100)-(hex), whereas aggregates of opened C(60) were found on the ZnOEP-modified Au(100)-(1 x 1) surface. Electrochemical responses of opened C(60) were significantly influenced by underlying ZnOEP arrays. This finding suggests that precise control of underlying ZnOEP adlayers with the Au atomic structure is important to recognize the opened C(60) on them.     

Novel phenoxyalkylamine derivatives. VII. Synthesis and pharmacological activities of 2-alkoxy-5-[(phenoxyalkylamino)alkyl]benzenesulfonamide derivatives.

To find a novel alpha-blocker with high alpha-blocking selectivity against dopamine D2-receptor affinity, we performed structural modification of the alkylene chains and the substituents on two benzene rings of 2-alkoxy-5-[(phenoxyalkylamino)alkyl]benzenesulfonamide derivatives. The modification of the alkylene chain between the amino moiety in the center of the molecule and the benzene ring (ring A) was found to be the most significant. 5-[2-[[2-(5-Fluoro-2-methoxyphenoxy)ethyl]amino]propyl]-2- methoxybenzenesulfonamide (II-4), which possesses 1-methylethyl as the alkylene chain, exhibited high alpha-blocking selectivity as well as potent alpha-blocking activity.     

Asymmetric total syntheses of (+)-mycoepoxydiene and related natural product (-)-1893A: application of one-pot ring-opening/cross/ring-closing metathesis to construct their 9-oxabicyclo[4.2.1]nona-2,4-diene skeleton

The total syntheses of (+)-mycoepoxydiene and (-)-1893A have been completed. The present synthetic strategy features the use of one-pot ring-opening/cross metathesis (ROM/CM) followed by a ring-closing metathesis (RCM) reaction, allowing for the concise construction of the 9-oxabicyclo[4.2.1]nona-2,4-diene framework from a 7-oxabicyclo[2.2.1]hept-2-ene derivative and 1,3-butadiene. The sequential metathesis product was converted into (+)-mycoepoxydiene through the oxidative rearrangement of a furfuryl alcohol to a pyranone, thereby establishing its absolute stereochemistry. From the common intermediate, a structurally related natural product (-)-1893A was also synthesized via the vinylogous aldol reaction.     

Control of photoinduced energy- and electron-transfer steps in zinc porphyrin-oligothiophene-fullerene linked triads with solvent polarity

The dramatic changes of the lifetimes of the charge-separated (CS) states were confirmed in zinc porphyrin (ZnP)-oligothiophene (nT)-fullerene (C(60)) linked triads (ZnP-nT-C(60)) with the solvent polarity. After the selective excitation of the ZnP moiety of ZnP-nT-C(60), an energy transfer took place from the (1)ZnP moiety to the C(60) moiety, generating ZnP-nT-(1)C(60). In polar solvents, the CS process also took place directly via the (1)ZnP moiety, generating ZnP(*+)-nT-C(60)(*-), as well as the energy transfer to the C(60) moiety. After this energy transfer, an indirect CS process took place from the (1)C(60) moiety. In the less polar solvent anisole, the radical cation (hole) of ZnP(*+)-nT-C(60)(*-) shifted to the nT moiety; thus, the nT moiety behaves as a cation trapper, and the rates of the hole shift were evaluated to be in the order of 10(8) s(-1); then, the final CS states ZnP-nT(*+)-C(60)(*-) were lasting for 6-7 mus. In the medium polar solvent o-dichlorobenzene (o-DCB), ZnP-nT(*+)-C(60)(*-) and ZnP(*+)-nT-C(60)(*-) were present as an equilibrium, because both states have almost the same thermodynamic stability. This equilibrium resulted in quite long lifetimes of the CS states (450-910 mus) in o-DCB. In the more polar benzonitrile, the generation of ZnP-nT(*+)-C(60)(*-) was confirmed with apparent short lifetimes (0.6-0.8 mus), which can be explained by the fast hole shift to more stable ZnP(*+)-nT-C(60)(*-) followed by the faster charge recombination. It was revealed that the relation between the energy levels of two CS states, which strongly depend on the solvent polarity, causes dramatic changes of the lifetimes of the CS states in ZnP-nT-C(60); that is, the most appropriate solvents for the long-lived CS state are intermediately polar solvents such as o-DCB. Compared with our previous data for H(2)P-nT-C(60), in which H(2)P is free-base porphyrin, the lifetimes of the CS states of ZnP-nT-C(60) are approximately 30 times longer than those in o-DCB.     

Preparation ,Structural Characterization and Luminescent Property of Binucleasr Silver（Ⅰ）Complex Formed by Benzotriazole and 1—Hydroxymethyl Benzotriazole

Dinuclear silver (I) six‐membered ring complex [Ag₂ (bta)₂ ‐(hmbta)₂] (ClO₄)₂ (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH₃CN)₄ClO₄. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm³ and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm³ and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement.     

Cadinene Derivatives from Eupatorium adenophorum

A new norsesquiterpene named eupatorone (= (4S,4aR,6R)‐1‐acetyl‐6‐(acetyloxy)‐4,4a,5,6‐tetrahydro‐4,7‐dimethylnaphthalen‐2(3H)‐one; 1 ) and a new sesquiterpene derivative named 2‐deoxo‐2‐(acetyloxy)‐9‐oxoageraphorone (= (1R,4S,4aR,6R,8aS)‐6‐(acetyloxy)‐3,4,4a,5,6,8a‐hexahydro‐4,7‐dimethyl‐1‐(1‐methylethyl)naphthalen‐2(1H)‐one; 2 ), together with the five known cadinene derivatives 3 – 7 were isolated from the flower of Eupatorium adenophorum (Spreng. ). Their structures were established by extensive NMR experiments, including 1D and 2D NMR.     

Carrier generation process on photoconductive polymer films as studied by magnetic field effects on the charge-transfer fluorescence and photocurrent

We have studied the magnetic field effects (MFEs) on the charge-transfer fluorescence and transient photocurrent of a 1,2,4,5-tetracyanobenzene-doped poly(N-vinylcarbazole) film, which reflect the recombination and escape yields of the carriers, respectively. The recombination yield dependence of the external magnetic field (B) clearly shows two types of the MFEs, growth with increasing B due to the hyperfine mechanism (HFM) and a negative dip due to the level-crossing mechanism (LCM). On the other hand, the escape yield indicates complementary MFEs with a sharp decrease in yield with increasing B and then a positive dip. Simultaneous observation of the HFM- and LCM-MFEs proves the stepwise hole-hopping mechanism rather the long-range hole-jumping one. The quantitative analysis of the recombination and escape MFEs is performed using the stochastic Liouville equations (SLE) for a one-dimensional lattice model in which the stepwise hole hops take place between the nearest neighbor carbazole units with spin conservation. The SLE analysis provides the recombination and hole transfer rate constants of 7.0 x 10(7) and 4.5 x 10(8) s(-1), respectively. The boundary site number for the ion pairs in the one-dimensional model is estimated by the best fit to the experimental results. The interionic distance of the boundary ion pair in the one-dimensional model including eight sites agrees with the thermalization distance in the Onsager model. Hence, it is concluded that the elementary processes in the Onsager model applied to molecular amorphous solids are the stepwise hole hops rather than a long-range hole jump.     

卤代化合物的光化学反应研究进展

介绍近年来卤代化合物在光照射下的偶联反应、醇解反应、消去反应、开环反 应，尤其是卤代杂环化合物的光化学反应，得到了许多用热反应或催化反应无法替 代的具有生物(理)活性的中间体．