燃烧-色谱法测定催化剂上碳含量标准物质的确定

利用燃烧-色谱法测定催化剂上碳含量采用外标法定量时,需要确定一种标准物作为定量的基础.在自主开发的燃烧-色谱高温定碳仪上,详细研究了草酸、碳酸钙和碱式碳酸镁3种物质的分解温度,根据3种物质的定碳常数测定了同一催化剂上的碳含量,并与化学法的测定结果进行了比较.结果表明,碳酸钙是测定催化剂上碳含量最合适的标准物质.     

新席夫碱与铜(Ⅱ)、铁(Ⅲ)在溶液中的配位反应研究

以1-(3-吡啶基)-1,3-丁二酮和1,3-二(2-胺基苯氧基)-2-丙醇进行缩合得到席夫碱1,3-二(2-胺基苯氧基)-2-丙醇缩双1-(3-吡啶基)丁烷-1,3-丁二酮(L),并通过单晶X射线衍射解析了Schiff碱配体(L)的结构。进一步将Schiff碱配体L与金属铜髤、铁髥进行配位反应。采用UV-Vis光谱技术,分别测定了铜髤、铁髥配合物的稳定常数。     

Heat-resistant and soluble fluorinated poly(amide imide)s based on non-coplanar ortho-linked diimide-dicarboxylic acid

A series of novel fluorinated heat-resistant poly(amide imide)s (PAIS) based on non-coplanar diimide-diacid monomer (DIDA) were synthesized and characterized. The poly(amide imide)s were obtained in high yields and possessed inherent viscosities in the range of 0.47-0.91 dL g⁻¹. All of the polymers were amorphous in nature, showed outstanding solubility and could be readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinoned, dimethyl sulfoxide, N,N-dimethylformamide, pyridine and tetrahydrofuran. Glass transition temperatures were in the range of 221-263 °C, as determined by differential scanning calorimetry. Degradation temperatures for 10% weight loss occurred all above 520 °C and char yields was more than 50% at 700 °C in nitrogen atmosphere. Moreover, these PAIs possessed low refractive indexes (n = 1.58-1.59), birefringence (Δn = 0.008-0.013), and dielectric constants (? ≈ 2.5) due to the trifluoromethyl pendent groups and ortho-catenated aromatic rings that interrupt chain packing and increase free volume.     

The synthesis, spectroscopic properties and X-ray structure of Zn(II) complexes with amino derivatives of chromone

Three new Zn(II) complexes containing the ligands 5-amino-8-methyl-4H-chromen-4-one (1), 6- or 7-amino-2-phenyl-4H-chromen-4-one (2, 3) were prepared. The new synthesised compounds were characterised by IR, ¹H NMR and MS spectroscopy. The crystal structure of complex 4 was determined with the use X-ray diffraction. The Zn(II) centre of 4 is linked by two chlorido and two N-bound aminochromone ligands, 1, in a strongly distorted tetrahedral configuration with the dissymetric point group C₂. The protonation constants of the ligands 1, 2 and 3 corresponded to 3.68, 3.88 and 6.83, respectively. The stability constants of the Zn(II) complexes were calculated from the potentiometric titration data. The complexes were found to have the formulae ML and ML₂ for ligands 1 and 2, and ML for ligand 3. Fluorescence spectroscopic properties were also studied; the strongest fluorescence in solution was exhibited by complex 6.     

有机和生物晶体固态核磁共振参数的准确预测

理论计算有助于复杂的有机和生物系统光谱的鉴定.对于核磁共振光谱,固体结晶中的化学位移和四极耦合常数(QCC)受到邻近的分子和晶格的氢键和范德华作用较大的影响,从而显示出与气态单体分子不同的NMR参数.因此,在固体晶体NMR参数的理论计算中有必要将氢键和范德华作用这两个因素考虑进来.基于周期性方法,本文采用L-Ala-Gly二肽和硝基苯晶体作为模型体系来考察该方法计算NMR参数的精度.研究结果显示周期结构模型能够将分子间的氢键和范德华作用考虑进来,得到的化学位移和QCC值明显优于传统的单分子模型和超分子模型得到的结果,采用该方法计算的结果能够重现NMR实验结果.     

Preparation of phosphinated bisphenol from acid‐fragmentation of 1,1,1‐tris(4‐hydroxyphenyl)ethane and its application in high‐performance cyanate esters

We reveal a route for the preparation of phosphinated bisphenol, 1,1‐bis(4‐hydroxyphenyl)‐1‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)ethane (2) , via a one‐pot reaction of 1,1,1‐tris(4‐hydroxyphenyl)ethane and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide (DOPO) in the catalysis of p‐toluenesulfonic acid. A two‐step reaction mechanism, acid‐fragmentation of 1,1,1‐tris(4‐hydroxyphenyl)ethane followed by nucleophilic addition of DOPO, is proposed for the synthesis. Based on (2) , a dicyanate ester derivative, 1,1‐bis(4‐cyanatophenyl)‐1‐(6‐oxido‐6H‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)ethane (3) was prepared and co‐cured with a commercially available dicyanate ester, the dicyanate ester of bisphenol A (BACY). Experimental data show that incorporating (3) into BACY enhances the flame retardancy and dielectric properties with little penalty to the thermal properties. A thermoset with T_g 274 °C, coefficient of thermal expansion (CTE) 49 ppm/°C, D_k 3.04 (1 GHz), T_d (5%,) N₂: 435 °C, air: 424 °C, and UL‐94 V‐0 rating can be achieved via this approach. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Direct dynamics study on mechanism and kinetics of the biradical self‐reaction of HOO

A theoretical study of the mechanism and the kinetics for the hydrogen abstraction reaction of the biradical hydroperoxy radical has been presented at the CCSD(T)/6‐311++G(3d,2p)//CCSD/6‐31+G(d,p) level of theory. Our theoretical calculations suppose a stepwise mechanism involving the formation of a postreactant complex in the triplet and singlet entrance channels. Four transition states of the six‐membered chain complexes (³TS1 and ¹TS1) and six‐membered ring complexes (³TS2 and ¹TS2) are located at the high dual level CCSD(T)/6‐311++G(3d,2p)//CCSD/6‐31+G(d,p) method. The rate constants of Path 1 ～ Path 4 at the CCSD(T)/6‐311++G(3d,2p)//CCSD/6‐31+G (d,p) level are calculated by means of the conventional transition state theory (TST) and canonical variational TST without and with small‐curvature tunneling (SCT) correction within the temperature range of 200–2,500 K. The calculated results show that the triplet channel is the dominating reaction channel and Path 2 is found to be the most favorable pathway. The rate constants of Path 2 are in good agreement with the experimental values at the experimentally measured temperatures. Moreover, the variational effect is not obvious in the low temperature range but is not neglectable in the high temperature range. The SCT plays an important role particularly in the low temperature range. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Investigation on Non-covalent Complexes of Cyclodextrins with Li+ in Gas Phase by Mass Spectrometry

To investigate the non-covalent interaction between cyclodextrins (CD) and lithium ion, a stoichiometry of α-CD, β-CD, heptakis(2,6-di-O-methyl)-β-CD (DM-β-CD), or heptakis(2,3,6-tri-O-methyl)-β-CD (TM-β-CD) was mixed with lithium salt, respectively, and then incubated at room temperature for 10 min to reach the equilibrium. In posi-tive mode, the electrospray ionization mass spectrometry (ESI-MS) results demonstrated that lithium ion can conjugate to α-, β-, DM-β- or TM-β-CD and form 1:1 stoichiometric non-covalent complexes. The binding of the complexes was further confirmed by collision-induced dissociation. The dissociation constants K_d1 of four complexes (Li+α-CD, Li+β-CD, Li+DM-β-CD, and Li+TM-β-CD) were determined by mass spectrometric titration. The results showed K_d1 were 18.7, 26.7, 33.6, 30.5 μmol/L for the complexes of Li+ with α-CD, β-CD, DM-β-CD, and TM-β-CD, respectively. K_d1 for the Li⁺ complexes of β-CD is smaller than that of DM-β-CD due to its steric effect of the partial substituted -CH₃. The Kd1 for the Li⁺ complexes of DM-β-CD is nearly in agreement with that of TM-β-CD, indicating Li⁺ is more likely to locate in the small rim of DM-β-CD's hydrophobic cavity. The DFT results showed through electrostatic interaction, one Li+ can strongly conjugate to four neighboring oxygen atoms. For the (α-CD+Li)⁺ complex, one Li⁺ may also situate the small rim of α-CD's hydrophobic cavity to form a non-specific host-guest complex.     

两个带呋喃悬臂不对称大环双核铜配合物的合成、结构及性质

合成并表征了2个不对称大环双核铜配合物[Cu₂（L¹）Cl₂]·CH₃CN（1）和[Cu₂（L²）Br₂]·CH₃CN·H₂O（2）。配合物与CT-DNA的作用通过紫外-可见光谱,粘度实验,圆二色谱和凝胶电泳实验进行了研究。紫外-可见光谱的结果表明配合物与DNA的结合常数分别为6.2×10⁵和7.2×10⁵,圆二色谱的实验表明配合物能与DNA较好的结合,粘度实验表明配合物与DNA的结合为非典型的插入模式,凝胶电泳实验显示配合物通过氧化机理对DNA有较强的切割活性。     

乙烯齐聚制α-烯烃反应体系的热力学研究

利用Benson基团贡献法计算了乙烯齐聚制α-烯烃反应各物质的标准摩尔生成焓、标准摩尔熵和摩尔定压热容,在298～700 K温度范围内对乙烯齐聚制α-烯烃反应体系的反应热、吉布斯自由能以及反应平衡常数进行了详尽的计算,分析了不同反应步骤的热力学平衡与限度,对不同反应发生的热力学可能性与顺序进行了判断,考察了反应温度和压力对乙烯齐聚制α-烯烃反应化学平衡的影响,确定了乙烯齐聚制α-烯烃反应体系适宜的工艺条件.结果表明:乙烯齐聚制α-烯烃反应为放热反应;从热力学上看,温度低于546 K时,乙烯齐聚生成直链α-烯烃反应为自发过程,且比α-烯烃异构化和烯烃歧化反应更容易进行;低温、高压有利于乙烯齐聚制α-烯烃反应的进行;乙烯齐聚制α-烯烃反应体系适宜的工艺条件为温度323～473 K,压力5～20 MPa,且在SHOP法的工艺条件下(温度363 K,压力10.3 MPa),乙烯齐聚生成直链α-烯烃反应的热力学平衡转化率接近于100%.