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941.
本文介绍一种自制环境等温型高温量热计, 其原理基于差热分析。在1300 K下所测纯铁等相变热与文献值吻合甚好, 证明仪器可靠。应用此仪器系统测量了Fe-Cr-V三元系九种不同成份的α-合金生成焓, 以及它们的α-α相变焓。为该体系的热力学研究提供了一些必要的热化学数据。 相似文献
942.
943.
Jayeon Hong Sangsub Kim Gyurim Park Yongmoon Lee Hyungchae Kim Sungjin Kim Tae-Woo Lee Changsoon Kim Youngmin You 《Chemical science》2021,12(25):8668
Polymer electroluminescence devices producing circularly polarized luminescence (CP PLEDs) have valuable photonic applications. The fabrication of a CP PLED requires a polymer host that provides the appropriate chiral environment around the emitting dopant. However, chemical strategies for the design of chiral polymer hosts remain underdeveloped. We have developed new polymer hosts for CP PLED applications. These polymers were prepared through a free-radical polymerization of 3-vinylcarbazole with a chiral N-alkyl unit. This chiral unit forces the carbazole repeat units to form mutually helical half-sandwich conformers with preferred (P)-helical sense along the polymer main chain. Electronic circular dichroism measurements demonstrate the occurrence of chirality transfer from chiral monomers to achiral monomers during chain growth. The (P)-helical-sense-enriched polymer interacts diastereoselectively with an enantiomeric pair of new phosphorescent (R)- and (S)-dopants. The magnitude of the Kuhn dissymmetry factor (gabs) for the (P)-helically-enriched polymer film doped with the (R)-dopant was found to be one order of magnitude higher than that of the film doped with the (S)-dopant. Photoluminescence dissymmetry factors (gPL) of the order of 10−3 were recorded for the doped films, but the magnitude of diastereomeric enhancement decreased to that of gabs. The chiral polymer host permits faster energy transfer to the phosphorescent dopants than the achiral polymer host. Our photophysical and morphological investigations indicate that the acceleration in the chiral polymer host is due to its longer Förster radius and improved compatibility with the dopants. Finally, multilayer CP PLEDs were fabricated and evaluated. Devices based on the chiral polymer host with the (R)- and (S)-dopants exhibit electroluminescence dissymmetry factors (gEL) of 1.09 × 10−4 and −1.02 × 10−4 at a wavelength of 540 nm, respectively. Although challenges remain in the development of polymer hosts for CP PLEDs, our research demonstrates that chiroptical performances can be amplified by using chiral polymer hosts.Polymer electroluminescence devices producing circularly polarized luminescence (CP PLEDs) have valuable photonic applications. 相似文献
944.
分散共聚法制备特殊形态高分子微球的研究 总被引:3,自引:2,他引:3
以聚乙二醇 (PEG)大分子单体为反应性稳定剂 ,在丙烯腈的分散共聚反应中添加少量苯乙烯以形成疏水性核 ,制备得到了亚微米级高分子微球 .透射电子显微镜研究表明 ,该高分子微球具有特异的形态结构 .同时研究了分散共聚体系中各种反应因素对微球形态和直径的影响 ,结果表明 ,苯乙烯单体的添加量、PEG大分子单体的浓度及分子量、混合溶剂的组成对微球直径和形态均有明显的影响 .X 射线光电子能谱 (XPS)研究结果表明 ,微球表面聚集有亲水性PEG链 ,核为疏水的聚 (丙烯腈 苯乙烯 ) ,即形成的特异形态的PEG接枝高分子微球亦为复合型结构 相似文献
945.
UB3LYP/6-31G(d) and ROMP2/6-311++G(d,2p) methods were used to calculate the Si-X bond dissociation energies (BDEs) of a number of para-substituted aromatic silanes (4-Y-C(6)H(4)-SiH(2)X, where X = H, F, Cl, or Li). It was found that the substituent effect on the Si-H BDE of 4-Y-C(6)H(4)-SiH(3) was small, as the slope (rho(+)()) of the BDE- regression was only 0.09 kJ/mol. In comparison, the substituent effect on the Si-F BDE of 4-Y-C(6)H(4)-SiH(2)F was much stronger, whose rho(+ )()value was -2.34 kJ/mol. The substituent effect on the Si-Cl BDE of 4-Y-C(6)H(4)-SiH(2)Cl was also found to be strong with a rho(+)() value of -1.70 kJ/mol. However, the substituent effect on the Si-Li BDE of 4-Y-C(6)H(4)-SiH(2)Li was found to have a large and positive slope (+9.12 kJ/mol) against. The origin of the above remarkably different substituent effects on the Si-X BDEs was found to be associated with the ability of the substituent to stabilize or destabilize the starting material (4-Y-C(6)H(4)-SiH(2)X) as well as the product (4-Y-C(6)H(4)-SiH(2)* radical) of the homolysis. Therefore, the direction and magnitude of the effects of Y-substituents on the Z-X BDEs in compounds such as 4-YC(6)H(4)Z-X should have some important dependence on the polarity of the Z-X bond undergoing homolysis. This conclusion was in agreement with that from earlier studies (for example, J. Am. Chem. Soc. 1991, 113, 9363). However, it indicated that the proposal from a recent work (J. Am. Chem. Soc. 2001, 123, 5518) was unfortunately not justified. 相似文献
946.
运用三足四齿配体三(2-甲基吡啶)胺(TPA)或三(2-甲基苯丙咪唑)胺(TBA),得到两个双核铁(III)配合物,[Fe2L2(μ2-O)(μ2-p-NH2-C6H4COO)]3+
(L = TPA, 1 和 L = TBA,
2)。两个配合物均为单斜晶系,空间群为P2(1)/c.晶胞参数 1: a =
1.4529(4), b = 1.6622(5), c = 2.0625(6) nm, β= 100.327(5)º,
V = 4.900(3) nm3, z = 4, F(000) = 2344, 分子量Mr = 1142.91, Dc
= 1.549 g/cm3, R1 = 0.0544,
R2 = 0.0962. 2: a = 1.3378(4), b = 2.1174(7), c =
2.4351(7) nm, β= 97.315(6)º, V = 6.842(4) nm3,
z = 4, F (000) = 3116, 分子量Mr = 1505.08, Dc
= 1.444 g/cm3, R1 = 0.0793, R2 = 0.1623. 在两个双核铁(III)配合物中,中心的三价铁和配体TPA或TBA上的四个氮原子和两个氧原子通过不同的桥形成一个畸变的八面体构型。 相似文献
947.
Li Qiu WANG Xiao Jun PENG* Rong ZHANG Guo Quan XU Jing Nan CUI State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 《中国化学快报》2003,(1)
Indocyanine dyes as fluorescent labeling reagents have been used in bioanalysis1,2. Arylsulfonate indocyanine dyes 1d and 1e developed by Waggoner A. S. et al.3,4 have excellent fluorescent properties combined with good aqueous solubility, are a new generation of fluorescent label compounds for proteins, oligonucleotides and other compounds containing hydroxyl, mercaptol or primary amine groups5. However, photostability of these dyes has been a problem. Z. G. YAO et al.6 reported that p… 相似文献
948.
The photochemical reaction of Re2(CO)10 with thiophene in hexane solution was investigated under vacuum. Three rhenium clusters: H2Re3(CO)12, HRe3(CO)14 and Re3(CO)14(OH)4, were isolated. The structure of Fellmann-Kaesz cluster Complex HRe3(CO)14 was determined by use of the X-ray diffraction method. The three rhenium atoms form a plane of symmetry and L: Re1Re2Re3 is 107°. The ten carbonyl groups bonded to the two terminal rhenium atoms Re1 and Re3, are staggered with respect to the central rhenium atoms. The bond lengths are 3.10 Å for Re2-Re3 and 3.34 Å for Re1-Re2. The bridging hydride is between Re1 and Re2. 相似文献
949.
ZHENG Li-Min FU Yan LIN Jian-Jun XIN Xin-QuanCoordination Chemistry State Key Laboratory Department of Chemistry Nanjing University Nanjing Jiangsu China 《中国化学》1994,12(3):243-247
The solid-solid state reactions of o-aminobenzoic acid with Zn(OAc)2.2H2O, Cu(OAc)2 .H2O, Ni(OAc)2.4H2O and Mn(OAc)2.4H2O result in the formation of corresponding complexes M(OAB)2 (M = Zn(Ⅱ), Cu(Ⅱ), Ni(Ⅱ), Mn(IⅡ)). XRD, IR and elemental analysis methods have been used to characterize the solid products. The activation energies of these reactions, which are calculated from the kinetic data obtained by means of the isothermal electrical conductivity measurement method, have been found to increase in the order: Cu(OAc)2.H2O(37.7 kJ.mol-1)~Mn(OAc)2.4H2O (39.7kJ.mol-1) < Zn(OAc)2.2H2O (56.3 kJ.mol-1) < Ni(OAc)2.4H2O (85.2 kJ.mol-1). The trend is related to their crystal structures. 相似文献
950.
本文介绍FAB质谱的原理、功能和优点。综述了FAB机理,讨论了影响FAB谱的因素。归纳了FAB法在金属有机配合物研究中的应用。 相似文献