检索结果-南通市图书馆

Theoretical study on thermal decomposition of azoisobutyronitrile in ground state

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2004年第5期47卷 373-380页

作者： SUN Chengke1,2, ZHAO Hongmei1 & LI Zonghe1 1. Department of chemistry, Beijing Normal university, Beijing 100875, China 2. Department of chemistry, Qujing Normal College, Qujing 655000, China 1. Department of chemistry Beijing Normal University 100875 Beijing China 2. Department of chemistry Qujing Normal College 655000 Qujing China

The thermal decomposition mechanisms of azoisobutyronitrile (AIBN) in the ground state have been investigated systematically. Based on the potential energy surfaces (PES) of various possible dissociation paths obtained using the semiempirical AM1 method with partial optimization, the density function theory B3LYP/6-311G* method was employed to optimize the geometric parameters of the reactants, the intermediates, the products and the transition states, which were further confirmed by the vibrational analysis. The obtained results show that the re- action process of the two-bond (three-body) simultaneous cleavage Me2(CN)C─ N=N─ C(CN)Me2? 2Me2(CN)C?+N2 is much more favorable than the reaction process of the two one- bond asynchronous cleavage Me2(CN)CN=N─C(CN)Me2 ? Me2(CN)CN=N?+ Me2(CN)C?? Me2(CN)C?+ N2. It was suggested that the electron shrinking effect of double bond (─N=N─) in AIBN and the stabilities of the Me2(CN)C?radical as well as N2 molecule are main factors of leading to the reaction proceeding in the former pathway. The calculation results were consistent with all the experimental facts.

关键词： azoisobutyronitrile, radicals, thermal decomposition, density function theory (DFT).

Synthesis,characterization,structures and magnetic property of chiral oxalate-bridged dicopper(Ⅱ) complexes

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2010年第6期53卷 1255-1260页

作者： WU Ling1,WANG Jun2,ZHU CaiFei1,LIN YiJi1,CHEN LeiQi1,FAN Jun2 & ZHANG Hui1 1State Key Laboratory of Physical chemistry of Solid Surfaces Department of chemistry,College of chemistry and Chemical Engineering,Xiamen university,Xiamen 361005,China 2School of chemistry and Environment,South China Normal university,Guangzhou 510006,China 1. State Key Laboratory of Physical chemistry of Solid Surfaces Department of chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China2. School of Chemistry and Environment South China Normal University Guangzhou 510006 China

The oxalato-bridged dicopper(II) complexes [Cu2(μ-ox)(LRR)2(H2O)2(ClO4)2] (1),[Cu2(μ-ox)(LRR)2(CH3COCH3)2(ClO4)2](1a),[Cu2(μ-ox)(LSS)2(H2O)2(ClO4)2] (2) and [Cu2(μ-ox)(LRR)(LSS)2(CH3COCH3)2(ClO4)2] (3) [LRR = (8R,10R)-(-)-[4,5]-pineno2,2′-bipyridine,LSS = (8S,10S)-(+)-[4,5]-pineno-2,2′-bipyridine;ox2= oxalate] were first prepared.A possible mechanism for the formation of the chial dicopper(II) complexes was *** on elemental analysis,conductance measurement,UV-Vis spectra,CD spectra and X-ray single-crystal diffraction,the oxalato-bridged structures of 1 and 2 were deduced to adopt two Cu(II) ions and the bridged oxalate lying in the nearly same *** crystal structures of 1a and 3 reveal that the coordination geometry around each Cu(II) ion is an elongated and distorted octahedron and two axial solvent molecules and two perchlorate ions are anti to each other respectively in both binuclear *** solution CD spectra of 1 and 2 in the visible d-d range show very weak Cotton effects with peaks at 588 and 779 nm,which are approximately of mirror image,suggesting the optical activities may be derived from the vicinal effects of the chiragenic centers at the pinene group of LRR and LSS,*** 1 has been characterized by variable-temperature magnetic susceptibility and the data was least-square fitted to the Blenaey-Bowers *** exchange integral J was found to be -338.41(4) cm-1,indicating a strong antiferromagnetic interaction between two copper(II) ions.

关键词： dicopper(II) complex chiral bipyridine μ-oxalate bridge crystal structure CD spectroscopy magnetic property

Synthesis, catalytic and biological activity of novel dinuclear copper complex with Schiff base

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2006年第3期49卷 225-229页

作者： WEI Danyi1,2, LI Ning1, LU Gui1 & YAO Kemin1 1. Department of chemistry, Zhejiang university, Hangzhou 310027, China 2. Institute of Inorganic chemistry, Ningbo university, Ningbo 315211, China 1. Department of chemistry Zhejiang University Hangzhou 310027 China 2. Institute of Inorganic chemistry Ningbo University Ningbo 315211 China

A novel dinuclear copper complex with tetraglycol aldehyde-phenylalanineSchiff base has been synthesized. It was characterized and formulated as [Cu_2L(NO_3)]NO_3 byelemental analysis, magnetic susceptibility, TG-DTA, IR, EPR and ~1H NMR spectra. The obtainedcomplex can be used as a good catalyst for the polymerization of methyl methacrylate (MMA). Theoptimum polymerization conditions are: MMA/catalyst = 500 (molar ratio); [catalyst] =7.5x10^(-3)mol·L^(-1); dioxane as solvent; 80℃; 6 h. Polymethyl methacrylate (PMMA) with 80%conversion, 7.2x10^5 viscosity-average molecular weight and 60.5% syndiotacticity was obtained. Thiscomplex has also been shown to play an important role in scavenging O_2^-.

关键词： novel copper complex, Schiff base, catalytic activity, scavenging effect of O-·2.

Electroluminescent properties of three ternary europium complexes with different phenanthroline derivatives

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2004年第4期47卷 326-334页

作者： BIAN Zuqiang1,2, GAO Deqing1, GUAN Min1, XIN Hao1, LI Fuyou1, HUANG Chunhui1, WANG Kezhi2 & JIN Linpei2 1. State Key Laboratory of Rare Earth Materials chemistry and Applications, Peking university, Beijing 100871, China 2. Department of chemistry, Beijing Normal university, Beijing 100875, China 1. State Key Laboratory of Rare Earth Materials chemistry and Applications Peking University 100871 Beijing China 2. Department of chemistry Beijing Normal University 100875 Beijing China

Three ternary Eu(III) complexes with general formula of Eu(DBM)3LN (DBM = dibenzoylmethanate, and LN (N = 1-3 ) stand for three different 1,10-phenanthroline derivatives) have been synthesized for vacuum deposition films-based electroluminescent devices. The complex Eu(DBM)3L3 (L3 = 2-phenyl-3-[3-(carbazol-9-yl)propyl]imidazo[4,5-f]1,10-phenan-throline) was designed with an effort to combine the electron-transporting phenanthroline platform and the hole-transporting carbazole group into one molecule expecting to improve both electron and hole transporting properties simultaneously. The results show that the variation of the neutral ligands in Eu(III) mixed ligand complexes is a simple and effective approach to the improvement in the thermal stability, PL and EL properties of materials. A double-layer device with the configuration of ITO/TPD (50 nm)/Eu(DBM)3L3 (50 nm)/Mg0.9Ag0.1 (200 nm)/Ag (100 nm) exhibited Eu(III)-based pure red emission with a maximum brightness of 561 cd/m2 at 16 V, and an onset driving voltage of 8 V. A device with the configuration of ITO/TPD (50 nm)/[Eu(DBM)3L3 (5 nm):BCP (5 nm)]4/BCP (20 nm)/AIQ (10 nm) Mg0.9Ag0.9 (110 nm)/Ag (100 nm) gave high efficient and pure red light emission with a luminance of 1419 cd/m2. Keywords dibenzoylmethane - electroluminescence - lanthanide - N ligands

关键词： dibenzoylmethane electroluminescence lanthanide N ligands

EXTRAPOLATION AND A-POSTERIORI ERROR ESTIMATORS OF PETROV-GALERKIN METHODS FOR NON-LINEAR VOLTERRA INTEGRO-DIFFERENTIAL EQUATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2001年第4期19卷 407-422页

作者： Shu-hua Zhang (Department of Mathematical Sciences, university of Alberta, Edrmonton, Alberta, Canada T6G 2G1) Tao Lin (Department of Mathematics, virginia Tech, Blacksburg VA 24061) Yan-ping Lin (Department of Mathematical Sciences, university of Alberta university of Alberta 加拿大 T6G 2G1 virginia Tech 美国 VA 24061 university of Alberta 加拿大 T6G 2G6

In this paper we will show that the Richardson extrapolation can be used to enhance the numerical solution generated by a Petrov-Galerkin finite element method for the initial value problem for a nonlinear Volterra integro-differential equation. As by-products, we will also show that these enhanced approximations can be used to form a class of posteriori estimators for this Petrov-Galerkin finite element method. Numerical examples are supplied to illustrate the theoretical results.

关键词： Volterra integro-differential equations Petrov-Galerkin finite element methods Asymptotic expansions Interpolation post-processing A-posteriori error estimators.

Structures and stability of isomers of[C,N,N,P]system

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2005年第5期48卷 415-423页

作者： KAN Wei1,2, ZHONG Hua1, YU Haitao1, FU Honggang1,3 & SUN Jiazhong1,3 1. School of chemistry and Materials Science, Heilongjiang university, Harbin 150080, China 2. School of chemistry and Chemical Engineering, Qiqihar university, Qiqihar 161006, China 3. State Key Laboratory of Theoretical and Computational chemistry, Institute of Theoretical chemistry, Jilin university, Changchun 130023, China 1. School of chemistry and Materials Science Heilongjiang University 150080 Harbin China 2. School of chemistry and Chemical Engineering Qiqihar University 161006 Qiqihar China 3. Jilin university State Key Laboratory of Theoretical and Computational Chemistry Institute of Theoretical Chemistry 130023 Changchun China

Nine isomers, twenty transition states, and some relative dissociation fragments of [C,N,N,P] system were located at the B3LYP/6-311G(d) and QCISD(t)/6-311+G(2df) (single-point) levels of theory, and the isomerization, structures, and stability of these obtained isomers were suggested. The results indicate that four nonlinear chainlike isomers NCNP, NCPN, CNPN, and CNNP with 2A′ electronic state are kinetically stable. Other isomers are kinetically unstable to-wards isomerization or dissociation because of the corresponding smaller reaction barriers. Furthermore, calculated vibrational frequencies, rotational constants, dipole moments, the first adiabatic ionization energies, and adiabatic electron affinities of the four isomers may provide some theoretical information that is helpful for identifying their existence in future laboratory and interstellar investigations. The results are also compared with [Si,N,N,P] system.

关键词： potential energy surface, [C,N,N,P] system, isomerization, kinetic stability.

Prediction of the thermodynamic properties of 1-alkyl-3-methylimidazolium lactate ionic liquids [C_nmim][Lact](n=2,3,4,5,and 6) by parachor

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2010年第12期53卷 2564-2570页

作者： FANG DaWei 1,3,TONG Jing 2,GUAN Wei 2,WANG Han 2 & YANG JiaZhen 1,3 1 Institute of Rare and Scattered Elements chemistry,Liaoning university,Shenyang 110036,China 2 College of chemistry,Liaoning university,Shenyang 110036,China 3 Key Laboratory of Rare and Scattered Elements,Liaoning Province,Shenyang 110036,China 1. Institute of Rare and Scattered Elements chemistry Liaoning University Shenyang 110036 China3. Key Laboratory of Rare and Scattered Elements Liaoning Province Shenyang 110036 China2. College of Chemistry Liaoning University Shenyang 110036 China

An ionic liquid (IL) based on lactate,1-butyl-3-methylimidazolium lactate ([C4mim][Lact]),has been prepared and characterized by 1H nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry (DSC).Since the IL can form strong hydrogen bonds with water,trace water is a problematic impurity in the *** the standard addition method (SAM),the density,refractive index and surface tension of [C4mim][Lact] were measured in the temperature range (308.15 to 343.15 ± 0.05) *** the basis of the experimental data,the parachor and molar volume for [C4mim][Lact],and the molecular volume V m,surface tension γ,molar enthalpy of vaporization △lgHm 0,refractive index n D,and the thermal expansion coefficients,for the homologues [Cnmim][Lact] (n=2,3,4,5,and 6) were estimated using semi-empirical *** estimated values are in good agreement with the experimental data.

关键词： parachor lactate ionic liquid density surface tension refractive index

Investigation of 'chazi'(damaged-enamels)on Chenghua doucai Porcelains

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第6期52卷 1722-1729页

作者： DU Feng1 & SU BaoRu2 1 Institute of chemistry & Molecular Engineering,Qingdao university of Science & Technology,Qingdao,China 2 College of Information Science & Technology,Qingdao university of Science & Technology,Qingdao,China Institute of chemistry & Molecular Engineering Qingdao University of Science & Technology Qingdao China College of Information Science & Technology Qingdao University of Science & Technology Qingdao China

At the end of the 1950s,Sun Yingzhou considered that the 'chazi'(damaged colour)on Chenghua doucai imperial porcelain as a defect was originally produced in firing process during Chenghua period(1465―1487).Researchers in China have accepted his *** any fragment with the 'chazi' has never been found in several tons of Chenghua imperial sherds excavated from Ming imperial kiln site in *** China,few scholars have questioned the formation of 'chazi',and further investigated *** researchers at the Research Laboratory in the British Museum,employing unde-structive EDXRF,have analyzed the chemical composition of the 'chazi'(damaged colour)on a Chen-ghua doucai stem cup in the museum,and they have confirmed that the 'chazi'(damaged colour)was caused by the fire of the Jianfu palace in the Forbidden City in *** on their research,the authors studied the colour chemical principle of the 'chazi's' formation *** to the ceramic technology principle,scientific reasoning for the 'chazi' was carried *** the help of the history of Qing court,the brainteaser of the 'chazi' was totally uncovered,the misunderstanding for the 'chazi' has also been *** research also suggests that employing modern science and technology is a direction to study Chinese ancient ceramic further.

关键词： Chenghua doucai porcelains court eunuchs the set on fire at the Jianfu palace ’chazi’(damaged-enamels) the British Museum colour chemical principle archaeology using science and technology

A multi-dimensional microcanonical Monte Carlo study of S_0→T_1 intersystem crossing of isocyanic acid

在线全文

学校读者我要写书评

暂无评论

Science China chemistry 2009年第11期52卷 1885-1891页

作者： ZHANG Feng1,2,FANG WeiHai1,LUO Yi2 & LIU RuoZhuang1 1 College of chemistry,Beijing Normal university,Beijing 100875,China 2 Theoretical chemistry,School of Biotechnology,Royal Institute of Technology,S-10691 Stockholm,Sweden 1. College of chemistry Beijing Normal University Beijing 100875 China 2. Theoretical chemistry School of Biotechnology Royal Institute of Technology S-10691 Stockholm Sweden

A general formula for the multi-dimensional Monte Carlo microcanonical nonadiabatic rate constant expressed in configuration space is applied to calculate the rate of intersystem crossing(ISC) between the ground(S0) and first excited triplet(T1) states for isocyanic ***-,two-and three-dimensional potential energy surfaces are constructed by coupled-cluster single-double CCSD calculations,which are used for Monte Carlo *** calculated S0→T1 ISC rate is in good agreement with experimental findings,which gives us a reason to believe that the multi-dimensional Monte Carlo microcanonical nonadiabatic rate theory is a very effective method for calculating nonadiabatic transition rate of a polyatomic molecule.

关键词： multi-dimensional Monte Carlo microcanonical nonadiabatic rate theory intersystem crossing isocyanic acid nonadiabatic transition