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971.
位阻型金属卟啉的合成 总被引:3,自引:0,他引:3
用平衡法合成了meso-四(2,3,5,6-四甲苯基)卟啉及其铁,锰,钴,锌金属配合物。 相似文献
972.
973.
用两种方法分别将四足配体铽配合物[TbL(NO3)]^2+和[TbL]^3+插层组装到了蒙脱土(MT)层板间,制备出超分子复合发光材料[TbL(NO3)^2+-MT和[TbL]^3+-MT。方法一:通过离子交换反应让配离子[TbL(NO3)]^2+取代钠+基蒙脱土(Na-MT)中的Na^+离子,插层组装到蒙脱土层板间。方法二:用配体L与铽基蒙脱土(Tb-MT)反应,使配体插入蒙脱土层板间与Tb^3+离子配位。用元素分析、XRD,FT-IR,UV-vis和热分析对材料进行了表征,并对其荧光性质进行了研究。结果表明,复合材料保持了蒙脱土良好的层柱结构特征,其层间距d001值与插层配离予的直径吻合较好,配离子以单层形式分布于蒙脱土层板间,复合材料中配合物的热稳定性有明显提高。在紫外光激发下,复合材料发出较强的Tb^3+特征荧光,其发射光谱与相应配合物的发射光谱很相似;复合材料中配合物的相对荧光强度较相应纯配合物有明显提高。荧光寿命较长;配合物的激发波长向可见光区发生位移,说明插层组装实现了对配合物激发波长的调制作用。 相似文献
974.
A new homogous series of thermotropic mesomorphic polyesters with high inherent viscosity has been synthesized. Mesogenic elements are separated by flexible spacers CO(CH2)nCO in the backbone. A study of their mesomorphic properties is reported. 相似文献
975.
用2-甲氧基-5-氯-1,3-苯二甲醛与含有不同取代基团X的邻氨基酚缩合,合成了一系列双Schiff碱L-X(X=OMe,diMe,Me,t-Bu,H,Cl,NO_2),它们与乙酸铜(Ⅱ)作用生成了一系列的双核配合物Cu_2L-X(OEt).用红外、紫外、磁天平、顺磁共振等手段对配合物进行了表征,并通过量化计算(CNDO/2法)探讨了配合物的成键性质。研究结果表明,该类配合物是一个较大的共轭体系,配合物中Cu(Ⅱ).Cu(Ⅱ)之间有较强的反铁磁性交换作用,其共轭程度和交换作用强弱皆随X基团的不同而呈现某种变化规律。 相似文献
976.
A novel concocting method to convert Triptolide (T) into Tripchlorolide (T(4)) in the traditional Chinese herb Tripterygium wilfordii Hook F. and a micellar electrokinetic capillary chromatographic (MEKC) approach by which the conversion of Triptolide (T) and Tripchlorolide (T(4)) was identified and determined had been established. Investigations of the influence of different pH values of boric acid and borax buffer and of sodium dodecyl sulfate (SDS) and organic additive concentrations had been carried out, and the optimum separation for T and T(4) was achieved using boric acid and borax of pH 7.0 with 30 mM SDS and 20% (volume ratio) methanol as the running buffer. It was found that MEKC exhibited good accuracy, precision and repeatability and the content of T(4) was greatly increased in the herb that was treated by the new concocting method. 相似文献
977.
The heat transfer mechanisms in inorganic hollow micro-spheres filled polymer composites are analyzed in the present paper. This heat transfer includes mainly three mechanisms: (1) thermal conduction between solid and gas; (2) thermal radiation between the hollow micro-sphere surfaces; and (3) natural thermal convection of the gas in the micro-hollow spheres. A theoretical model of heat transfer in polymer/inorganic hollow micro-sphere composites is established based on the law of minimal thermal resistance and the equal law of the specific equivalent thermal conductivity, and a corresponding equation of effective thermal conductivity is derived. The effective thermal conductivity (keff) of hollow glass bead-filled polypropylene composites is estimated by using this equation, and is compared with the numerical simulations by means of a finite element method. The results show that the variation of the theoretical estimations of keff are similar to the numerical simulations at lower filler volume fraction (φf20%). Moreover, keff decreases linearly with increasing φf, and reduces somewhat with increase of filler size. 相似文献
978.
Ab initio LCAO-MO-SCF calculations for several typical molecules containing phosphorushave been undertaken to study the role of phosphorus 3d orbitals in the bonding.It is emphasizedthat the discussion about the 3d orbital participation in bonding should be based on a reasonable choiceof basis sets and it seems suitable to choose the atomic orbitals in proper molecular environment asthe basis set.As an approximation,the optimized minimal STO-NG basis sets have been adoptedin the present paper.The results obtained well exhibit the model of 3d orbital participation in bonding.It is shown that under the influence of highly electronegative ligands the phosphorus 3d orbitals con-tract greatly,their energy levels drop considerably,and thus they can effectively participate in bond-ing.The presence of highly electronegative ligands seems necessary.The contribution of 3d orbitalsto bonding is achieved mainly through the concertedformation of σ bonds and p-d backbonds,thoughthe contribution to σ bonding is minor.The three-center,four-electron bond modelis only approxi-mately correct.The results of the present paper demonstrate that the model of 3d orbital participationin bonding favoured by experimental chemists is reasonable and possesses sound ground. 相似文献
979.
A detailed singlet potential energy surface(PES) of [Si,C,O,O] system including a van der Waals (vdW) comples SiO……CO2,eight isomers,and twelve transiton states is investigated by MP2 and QCISD(T) (single-point)methods.At the final QCISD(T)/6-311 G(2df)//MP2/6-311G(d) level with zero-point energy included,the complex SiO……CO is found to be thermodynamically and kinetically the most stable species.Although eight ismoers are located as local energy minima,they are rather unstable toward isomerization to the dissociation fragments or comples.For the reaction of silocon atoms with carbon dioxide,two competitive reaction channels are found,and the primary pathway,which leads to the products of SiO and CO fragments,is the direct oxygen-abstraction process from carbon dioxide by silicon atom with a41.16 kJ/mol reaction barrier height.Our predications are in good agreement with previous experimental and theoretical studies. 相似文献
980.