Effect of configuration and conformation on the spin multiplicity in xylylene type biradicals

The singlet-triplet splitting energy gap ΔEs-T= Es - ET is calculated for the ortho-, meta-, and para-xylylenes and their heteroatomic analogous by means of AM1-CI approach. It is shownthat when the radical centers R(R=H2C- ,H2N - or HN'- ) are twisted sufficiently far out ofconjugation with the benzene ring, ΔEs-T tends to zero or is negative, i.e. ortho-, meta-, and para-phenylenes turn into weak ferromagnetic or antiferromagnetic coupling unit, while they are strong ferromagnetic (meta-isomers) or antiferromagnetic (ortho-, para-isomers) coupling units under planar conformation. It is suggested that serious twisted conformation is not recommended candidate for the design of novel high-spin molecules with stable high-spin ground states by ortho-or para-phenylene coupling unit.     

NO及NO2与In/HZSM-5催化剂相互作用的微量量热研究

自从Iwamoto[1]和Held等[2]报道了在离子交换法制备的Cu-ZSM-5催化剂上烃类可以选择性催化还原(SCR)氧化氮后,基于分子筛的催化剂在这一反应中得到了广泛的研究,以期取代传统的NH3-SCR过程.     

同时测定水中阴,阳离子的单柱阴离子排斥—阳离子交换色谱法

采用单柱离子色谱系统和电导检测的方法,以丙二酸为淋洗液,同时有效地分离、检测了溶液中ＳＯ４＾２－、Ｃｌ＾－、ＮＯ３＾－、Ｆ＾－、ＮＨ４＾＋、Ｋ＾＋、Ｍｇ＾２＋、Ｃａ＾２＋９种离子。研究了丙二酸浓度和流速对各离子保留时间及电导检测行为的影响。该法用于目前市售饮用水中的阴阳离子分析,得到了满意的结果。     

Syntheses and Complexing Properties of Polyethers

Diaza-18-crown-6 with two 8-hydroxyquinolines as side arms show high selective complexing ability with metal ions^[1,2] and with two aminophenols exhibit strange property^[3]. 8 diaza-18-crown-6 ethers containing sidearms^[4] and 7 podands were synthesized. Their complexing ability with metal ions were studied, the results show that they present high complexing capability for metal ions. The polyethers containing 8-hydroquinoline fragment show high selectivities for Hg²⁺,Ni²⁺ and their complexes with Eu³⁺ and Tb³⁺ show strong luminescence.     

Synthesis under Micromave Irradition and Crystal Structure of 4''-Acetylbenzo-15 -crown-5thiosemicarbazone

The title compound is a bifunctional receptors including a thiourea group and a crown ether ring. Due to many possible potentials as a new class of reagents for membrane transports,ion-selective electrodes as well as reaction catalysts, the design and synthesis of bifunctional receptors for simultaneous binding of cations and anions is of ongoning interest in srprarnolecular chemistry1-5. In bifunctional receptors, the binding sites for anions and cations are covalently linked so as to exhibit allosteric or cooperative complexation where the binding affinity for anions(cations)is modified as a result of the cation(anion) complexation.Literature[6] reported that the ability of the thiourea group to bind anions is significantly enhanced when Na+ is bound to the crown moiety. To date, however only a few receptors of this class have been reported.6-8In this paper, we report an improved procedure under microwave irradiation that gives higher yields of title compound and needs fewer reaction times than traditional method.The structure of this compound was determined by IR ,element analysis and X-ray analysis.Scheme 1 The reaction equationThe crystal belongs to triclinic crystal system, P-1 space group, a=0.9547(0)nm, b=1.3637(3)nm,c=1.6029(3)nm, α =75.33(3) , β =83.62(3) , γ =70.99(3) ,Z=4,Dc=1.335g/cm3,F(000)=816,R1= 0.0557 ,wR2=0.1281. It is assembled into a three-dimensionalsupramolecule by intermolecular hydrogen bonds.     

Molecular Spectroscopic Study on the Interaction between Heparin and Neutral Red

The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.     

Construction of Hybrid Enzyme from HEC-SOD and Cu,Zn-SOD

Human extracellular superoxide dismutase(hEC-SOD) is a secreted tetrameric protein involved in the protection of a human body from oxygen free radicals. Its three-dimensional structure has not been confirmed, hEC-SOD couldn′t be expressed in E.coll. We constructed a hybrid enzyme, which comprises the Nterminal and C-terminal domains from hEC-SOD, fused it to human Cu, Zn-SOD. The hybrid enzyme is expressed successfully in E. coli. Further, we analyzed the expression of hEC-SOD in E. coli by mRNA differential displaying.     

Stereoselective Synthesis of Piperamide Alkaloids by Modified Ramberg-Bcklund Reaction

A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time.     

C_nP_4~4(n=1～7)团簇结构与能量的密度泛函研究

使用分子图形软件设计出多种CnP-4(n =1～ 7)的结构模型 ,并进行B3LYP密度泛函几何构型优化和振动频率计算 .最稳定的CP-4和C2 P-3 都是平面环状结构 .最稳定的CnP-4(n =3 ,5 ,7)结构在直碳链的一端连接 1个磷原子且另一端是P3 C的四元环的平面结构 .最稳定的CnP-4(n =4,6)结构在直碳链的一端连接 1个磷原子且另一端是P3 的三元环的锄状结构 .直碳链可与平面环的磷原子生成大π键 .大多数构型是由C2 ,C3 ,C4子结构以环状或链状方式组成的 .碳原子与磷原子以交替方式排列的结构数量少、能量高 .     

Catalytic Enantioselective Reduction of Prochiral Ketones with Chiral Ferrocenyl Amino Alcohols

The asymmetric reduction of prochiral ketones was catalyzed by a class of recoverable and highly stable chiral ferrocenyl amino alcohols derived from natural amino acids to yield optically active secondary alcohols in high chemical yields and moderate to good enantiomeric excesses.