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Disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O) is an attractive candidate for phase change materials. The main problem for its practical use comes from incongruent melting character during thermal cycling. Experimentally, heat of fusion of the pure salt decreased from 200 to 25 jog 1 in a four-run freeze-thaw cycling. Additives such as thickening agent or in-situ synthesized polyacrylate sodium in the molten salt can prevent its phase separation to some extent. In the test, sodium alginate 3.0%-5.0% (w/w) thickened mixture containing Na2HPOn·12H2O and some water showed constant heat storage capacities. Polyacrylate sodium gelled salt was synthesized through polymerizing sodium acrylate in the melt of Na2HPOn·12H2O and some extra water at 50 ℃. Optimum conditions composed of sodium acrylate 3.0%-5.0% (w/w), cross-linking agent N,N-methylenebis-acrylamide 0.10%-0.20% (w/w), K2S208 and Na2SO3 (mass ratio 1 ; 1) 0.06%-0.12% (w/w). As opposed to normal large crystals of pure Na2HPOn·12H2O in solid state, the gelled salt existed in a large number of tiny particles dispersed in the gel network at room temperature, commonly less than 2 mm. But only those sample particles with sizes less than 0.2 mm may have relatively stable thermal storage property. A problem encountered was the poor reproducibility of the synthesis method: heat storage capacity of the product was often very different even though the synthesis was carried out in the same conditions. An alternative gelling method by sodium alginate grafted sodium acrylate was tried and it showed a fairly good effect. Heat capacities and heat of fusion of Na2HPO4·12H2O were measured by an adiabatic calorimeter.  相似文献   

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Epothilones belong to a class of novel microtubule stabilizing and anti-mitotic agents, which have a paclitaxel-like mechanism of action. A three-dimensional quantitative structure-activity relationship (3D-QSAR) model was built for epothilones by the method of comparative molecular field analysis (CoMFA) combined with the flexible docking technology. The docking CoMFA model gave a good cross-validated value of q2=0.784 with an optimized component of 6 and the conventional correlation coefficient of r^2=0.985. The statistical results show that the model has good ability to predict the activity of the studied compounds. At last, the docking CoMFA model was analyzed through contour maps complemented with MOLCAD-generated active site potential surface in the α,β-tubulin receptor, which can provide important information for the structure-based drug design.  相似文献   

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雌激素类化合物由于其对人和野生动物健康的负面影响而受到广泛关注.雌激素受体存在α和β两种亚型,由于雌激素β受体(ERβ)与α受体(ERα)两者结合腔中的氨基酸序列存在明显差异,因此配体化合物在与雌激素β受体和α受体的结合活性和模式上也可能存在较大差别.本文以50个与雌激素β受体结合的化合物为研究对象,应用比较分子相似性指数分析(COMSIA)的三维定量结构-活性关系(3D-QSAR)分析方法研究化合物结构与活性之间的关系,比较了原子契合和基于受体结构两种分子叠合方式对模型质量的影响,建立了相关性显著、预测能力强的定量活性预测模型(R^2=0.961,qLOO^2=0.671,R^2Pred=0.722),并结合分子对接方法揭示了影响化合物活性的分子结构特征和分子机理.  相似文献   

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贡雪东  董海山 《结构化学》1999,18(2):124-130
1INTRODUCTIONBenzotrifuroxan(BTF)isapowerful,hydrogenfreandrelativelysensitiveexplosive.Sincethiscompoundwasfirstprepared,i...  相似文献   

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The title complex,[Zn(ip)2(H2O)2][ZnCl4]·H2O·2DMF 1(ip=imidazo[4,5-f][1,10] phenanthroline),has been synthesized via the slow evaporation of concentrated reaction solution at room temperature.It was characterized by single-crystal X-ray diffraction.Crystal data for C32H36Cl4N10O5Zn2:white prism,0.17mm×0.15mm×0.10mm,monoclinic,space group P2/c,a=11.928(8),b=9.868(6),c=16.520(11),β=104.879(12)°,V=1879(2)3,Z=2,Mr=913.25,Dc=1.614 g/cm3,F(000)=932,μ=1.616 mm-1,λ(MoKα)=0.71073,GOOF=1.045,R=0.0710 and wR=0.1755 for 3055 observed reflections with Ⅰ2σ(Ⅰ).X-ray diffraction study reveals that the title complex has an interesting 3D architecture via hydrogen bonding interactions and π-π interactions.The IR,TGA,XRD and luminescent properties of complex 1 were also studied.  相似文献   

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A new 3-D hybrid framework {[(dafone)PbI2](dafone)2}n 1 (dafone = 4,5-diazafluoren-9-one) has been prepared and structurally determined. 1 crystallizes in the monoclinic system, space group C2/c with a = 24.109(8), b = 16.596(8), c = 7.983(3)A, β = 91.590(15)°, V = 3193(2)A^3, Z = 4, C33H18I2N6O3Pb, Mr = 1007.53, Dc = 2.096 g/cm^3, F(000) = 1880, μ(MoKα) = 7.262 mm^-1, the final R = 0.0352 and wR = 0.0951 for 3198 observed reflections with I 〉 2σ(I). In the [(dafone)PbI2]n chain, the Pb center adopts a distorted octahedral coordination geometry and shares an edge to give a one-dimensional polymer. The 3-D arrangement of 1 constructs from H-bonds among dafone molecules and π-π stacking interactions among dissociative dafone molecules. These weak interactions contribute to the stability of the title compound. DFT calculation was carried out to reveal its electronic structure.  相似文献   

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A unique metal-organic framework [Cd2(L)1.5(μ3-OH)(H2 O)2 ]·2H2 O(1, H2 L = 2,5-dibenzoylterephthalic acid) has been synthesized under hydrothermal conditions, and characterized by single-crystal X-ray diffractions, elemental analyses, IR spectra and fluorescence spectrum. The compound is of triclinic system, space group P1, C33 H27 CdO14, Mr = 870.33, a = 12.2939(17), b = 12.5135(9), c = 13.2046(10), α = 115.3190(10), β = 96.9140(10), γ = 109.7950(10)°, V = 1641.6(3)3, Z = 2, Dc = 1.761 g/cm3, F(000) = 862, μ(MoK) = 1.366 mm-1, Rint = 0.0148, R = 0.0240 and wR = 0.0639 for 5995 observed reflections with I 2σ(I). X-ray analysis shows that the title complex exhibits a 3D framework with(412·63) topology, in which the tetra-nuclear [Cd4(μ3-OH)2 ] clusters act as 6-connected nodes, and the L ligands can be simplified to be linear connectors. Moreover, the thermal stability and fluorescence have been studied in detail.  相似文献   

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A new complex,[Cd(L)2(pbda)]n(1,L = 3-(2-pyridyl)-4-(p-methoxyphenyl)-5-(2-thienyl)-1,2,4-triazole,H2pbda = 1,4-benzenedicarboxylic acid),has been hydrothermally prepared and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and PXRD.The complex crystallizes in monoclinic,space group P21/c with a = 8.2929(9),b = 21.668(2),c = 10.9940(11) ,β = 90.242(2)o,V = 1975.5(4) 3,Z = 2,C44H32N8O6S2Cd,Mr = 945.30,Dc = 1.589 g/cm3,μ = 0.721 mm-1,S = 1.097,F(000) = 960,the final R = 0.0590 and wR = 0.1045 for 3846 observed reflections(I > 2σ(I)).In the title complex,the rigid bridging pbda2-ligands utilize oxygen atoms of carboxylate groups to coordinate with Cd(II) atoms to form one-dimensional chains which are further interlinked into a three-dimension framework via the intermolecular weak interactions.Photoluminescence study revealed that complex 1 exhibits strong fluorescent emission band in the solid state at room temperature.  相似文献   

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