Eu8(NCN)5-deltaI6+2delta (delta= 0.05): a novel rare-earth carbodiimide iodide containing oligomeric tritetrahedral Eu8 clusters

Eu8(NCN)4.95I6.10 is the first compound with discrete tritetrahedral Eu8 clusters which are interconnected by coordinating NCN2- carbodiimide anions on their triangular faces to form separated layers, the latter being bridged by iodide and carbodiimide anions.     

Diclobutrazol的合成及其生物活性研究

Ｄｉｃｌｏｂｕｔｒａｚｏｌ的合成及其生物活性研究张洪奎，廖联安，陈明德，叶向阳，郭奇珍（厦门大学化学系厦门３６１００５）关键词：Ｄｉｃｌｏｂｕｔｒａｚｏｌ，相转移催化，合成，生物活性Ｄｉｃｌｏｂｕｔｒａｚｏｌ（１）俗名粉锈清，是一种广谱内吸性杀菌剂，...     

固-液相转移催化1,2,4-三唑N-烷基化的研究

本文研究了相转移催化条件下的1,2,4-三唑烷基化反应。评价了几种相转移催化剂,结果表明PEG是合适的固-液相转移催化剂。在相转移催化剂作用下,用不同的烷基化剂制备了一系列N-1取代的1,2,4-三唑,并对实验的结果进行了讨论。     

Synthesis and magnetic properties of trinuclear nickel(II) complexes bridged by α-benzyldioximato groups

Four new NiII–NiII–NiII homotrinuclear complexes namely [Ni(-BD)2{NiL2}](ClO4)2 [L = 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (5-NO2-phen), 2,2-bipyridyl (bpy) or 4,4-dimethyl-2,2bipyridyl (Me2bpy) and (-BD)– = -benzyldioximato ion] have been prepared and characterized. Based on elemental analyses, i.r. spectra, conductivity measurements, extended -benzyldioximato-bridged systems consisting of three nickel(II) ions in which the central nickel(II) ion has a square-planar environment and the end capped two nickel(II) ions have a distorted octahedral environment are proposed for these structures. The temperature dependence of the magnetic susceptibility for complexes (1) (phen), (2) (5-NO2-phen), (3) (bpy) and (4) (Me2bpy) were measured over the 77–300 K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator (H^ = –2JS^1S^2), giving the exchange integral J = –13.31 cm–1 for (1), J = –7.37 cm–1 for (2), J = –8.96 cm–1 for (3) and J = –7.33 cm–1 for (4) These results indicate a weak antiferromagnetic spin exchange interaction between the two terminal nickel(II) io     

Dual behavior of masked o-benzoquinones in intramolecular Diels-Alder reactions. Expedient synthesis of highly functionalized cis-decalins from 2-methoxyphenols

[Reaction: see text]. The potential dual behavior as dienes and dienophiles of the diene moieties of masked o-benzoquinones (MOBs) 10a-e-12a-e, generated upon oxidation of 2-methoxyphenols 1-3 with BTIB in the presence of appropriate dienols, in their intramolecular Diels-Alder (IMDA) reactions has been examined. The IMDA reactions of MOBs 10a-d, 11a,b,d, and 12a,b,d resulted in highly functionalized oxatricyclic compounds 18a-d, 19a,b,d, and 20a,b,d, respectively, with concomitant formation of cis-decalin derivatives 21a-d, 22a,b,d, and 23a,b,d in a highly regio- and stereoselective manner. However, the MOBs 10e-12e provided exclusively oxatricyclic compounds 18e-20e. The formation of cis-decalins in these IMDA reactions illustrates the dienophilic character of MOBs, in addition to their behavior as dienes. The ratio of the two cycloadducts obtained in each reaction as a result of the dual character of MOBs depends on the nature and/or position of the substituents on both the cyclohexadienone moiety and the added 2,4-dienol. The majority of the cycloadducts resulted from the diene property of MOBs in intramolecular Diels-Alder reactions smoothly underwent Cope rearrangement to furnish cis-decalins as sole products in excellent to quantitative yields that provides a short and efficient entry to polyfunctionized cis-decalins from 2-methoxyphenols. Furthermore, the variation of dienophilic and diene characters of MOBs in the IMDA reactions with the electron-donating or electron-withdrawing substituent of both cyclohexadienone moiety and the added conjugated acyclic diene or 2,4-dienol has been studied in detail.     

铈、镨二乙基磷酸盐的晶体结构

合成了Ce[PO_2(OC_2H_5)_2]_3和Pr[PO_2(OC_2H_5)_2]_3(简称Ce(DEP)_3和Pr(Pr(DEP)_3)。用四圆衍射仪测定了其晶体结构。它们均属三斜晶系,空间群P1。晶胞参数,对Ce(DEP)_3:α=10.324(4)A,b=12.861(4)A,c=13.998(5)A,x=106.49(3)°,β=112.83(4)° γ=115.61(3)°,V=1296(1)A~3,Z=2;对Pr(DEP)_3:α=10.27(1)A,b=11.81(1)A,c=12.51(1)A,x=109.93(9)°,β=111.9(9)°,γ=93.0(1)°,V=1293(3)A~3,Z=2。用Patterson法并经分块全矩阵最小二乘法修正,最后的R值,Ce的为0.1071,Pr的为0.1066。结构分析指出,两种配合物结构类似,Ce和Pr原子均由二乙基磷酸根的六个氧原子配位形成八面体构型。     

A graphical method to construct a phylogenetic tree

A 3D graphical representation of DNA sequences, which has no circuit or degeneracy, is derived for mathematical denotation of DNA sequence. Based on this graphical representation, we propose a new sequence distance measure. We make use of the corresponding similarity matrix to construct a phylogenic tree by virtue of the fuzzy theory. The examination of phylogenic tree belong to eight species illustrates the utility of our approach. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Tocopherols and Triterpenoids from Sida acuta

A new tocopherol derivative, 7_a‐methoxy‐α‐tocopherol ( 1 ), and a new taraxastane triterpene, taraxast‐1,20(30)‐dien‐3‐one ( 5 ), together with four known compounds, β‐tocopherol ( 2 ), α‐tocopherol ( 3 ), α‐tocospiro B ( 4 ) and taraxasterone ( 6 ) were isolated from the whole plant of Sida acuta. Their structures were elucidated by spectral analysis including MS, 1D and 2D‐NMR spectroscopy. Among those compounds, compounds 1 , 2 , and 3 showed significant antioxidant effect (EC₅₀ = 86.9, 68.2, and 70.9 μM, respectively) in the DPPH radicals scavenging activity assay.     

Observations on the swelling characteristics of the zwitterionic hydrogel of poly(1-3-sulfopropyl)-2-vinyl-pyridinium-betaine hydrogel

Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA). The densities of the resultant xerogels increased regularly with the content of MBA. Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis. The water contents increased with decreasing content of MBA, the value of 92.7 wt% at the lowest MBA content being higher than that for other zwitterionic hydrogels. Enhanced swelling occurred in 1 M aq. KSCN at each MBA content, the total swelling being 98.1 wt% at the lowest crosslinker content. Swelling increased with increasing temperature. An approximate procedure to formulating swelling equilibrium in term of the volume fraction of water in hydrogel, in conjunction with the van’t Hoff equation, yields a small positive value for the enthalpy of swelling. This is compared with values derived similarly for other hydrogels.     

First total synthesis of a natural product containing a chiral,beta-diketone: synthesis and stereochemical reassignment of siphonarienedione and siphonarienolone

The first total syntheses of siphonarienolone and siphonarienedione are described. The development of a stereoselective synthesis of beta-diketones facilitated the synthesis of the latter compound. The synthesis of the structures proposed for the natural products afforded compounds whose spectral data did not match those of the natural products. However, the synthesis of compounds isomeric to the proposed structures at C(4) and C(5) afforded compounds identical to the natural products, thereby reassigning the stereochemistry of the natural products.