稀土复合氧化物Ln_2CuO_4催化苯酚羟化反应的研究

合成了K_2NiF_4结构的Ln_2CuO_4(Ln=La,Pr,Nd,Sm,Gd)类钙钛石型复合氧化物催化剂.研究了这些稀土取代的类钙钛石型复合氧化物的固态物理,化学性质.探讨了此类复合氧化物在苯酚羟化反应中的催化作用.考查了催化剂结构和组成与其苯酚羟化活性的关系,结果表明,在K_2NiF_4型复合氧化物中,A位稀土取代效应对复合氧化物的苯酚羟化催化活性有很大影响.

稀土富勒烯提取液的激光解吸飞行时间质谱研究

采用激光解吸飞行时间质谱对含镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钐(Sm)、铕(Eu)、钆(Gd).铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)等13种稀土富勒烯的提取液进行了研究.考察了正负谱、激光强度、底物以及质量歧视对分析结果的影响,并由此确定了最佳分析条件.结果表明,提取液中除了空心富勒烯外,还存在较多量的稀土富勒烯.通过对它们谱峰相对强度之间的比较,探讨了不同稀土元素嵌入富勒烯球笼的结构稳定性及溶解性能的差别以及产生这种差别的可能原因.

双镥金属富勒烯的合成、提取与表征

自La@C_(82)被发现以来,能导致新分子、新材料不断涌现的金属富勒烯的研究就一直是富勒烯化学领域中最吸引人的分支,但是它的发展比较缓慢,直到K-H方法被应用于宏观量地合成金属富勒烯,这种情况才有所改善.现在,大多数镧系元素,包括La,Ce,Nd,Sm,Eu,Gd,Tb,Dy,Ho和Er,已通过金属/碳棒在低压氦气条件下的电弧放电过程被成功地包裹于富勒烯碳笼当中并被溶剂提取出来,它们提取液的质谱图均给出明显的M@C_(82)信号.与此相反,我们这里报道了一种特殊的镧系元素——镥,在它的金属富勒烯提取液中,只有双镥富勒烯,Lu_2@C_(2n),能被激光解吸电离飞行时间质谱与解吸电子轰击质谱观察到.含富勒烯与双镥富勒烯的碳炱用电弧放电法制备.简单来说,直径6mm的光谱纯碳棒,钻孔,填入99.99%Lu_2O_3与碳粉的混合物,使总原子比为1.0Lu/100C,此金属/碳的混合棒先在真空条件下(10~(-3)×133.332 Pa),2000 K处理3h,然后作为正极在160×133.332 Pa氦气中直流电弧放电,电弧电流80A.生成的碳炱用甲苯索氏提取后,再于高压釜中523 K时,

Effective interface of a composite membrane serving as an ideally ultrathin barrier layer

A novel idea relating to the selective barrier layer of a composite membrane is described. The effective interface of the composite membrane could act as a barrier layer which could be controlled to an ideally ultrathin thickness. A new type of polyamide composite membrane was prepared according to this idea, which possessed permeability and chemical resistance more than one magnitude greater than those of ordinary polyamide composite membranes. Copyright (C) 1996 Elsevier Science Ltd.

Luminescence of Pb2+ and energy transfer from Pb2+ to rare earth ions in silicate oxyapatites

The Pb2+ luminescence in a series of silicate oxyapatites Me(2)(Y, Gd)(8)(SiO4)(6)O-2, Me(4)Y(6)(SiO4)(6)O (Me = Mg: Ca, Sr) is reported and discussed in relation to the crystal structure. The maximum wavelengths of the excitation (S-1(0)-P-3(1)) and emission (P-3(1)-S-1(0)) bands of Pb2+ are independent of the Mc:Y ratio (2:8 or 4:6) but they have lower energies in MgY-oxyapatites than in CaY- and SrY-oxyapatites. The Stokes shift of Pb2+ luminescence amounts to 11 100 to 11 400 cm(-1): which does not depend strongly on the host composition. There exists a mutual energy transfer between Pb2+ and Gd3+ in Sr2Gd8(SiO4)(6)O-2. At last, the dependence of the energy transfer efficiency of Pb2+-Sm3+, Tb3+: Dy3+ in Sr-2(La: Gd)(8)(SiO4)(6)O-2 and Ca-2(Y, Gd)(8)(SiO4)(6)O-2 on their doping concentrations was studied in more detail.

Chlorination and oxidation of aromatic polyamides .2. Chlorination of some aromatic polyamides

The effects of chlorine on three kinds of aromatic polyamides: those not containing a substituent, those containing substituents, and those containing heterocyclic aromatic rings, were studied. The correlations between the chemical structures of polyamides and the reactivity to hypochlorous acid were examined by IR and C-13 solid-state NMR spectra before and after chlorination. It was found that the chlorination of polyamides depends not only on their chemical structures but also on chlorination conditions such as pH value and reaction time. Their response to chlorination corresponds to four types: ring-chlorination, no reaction, N-chlorination, and chain cleavage. (C) 1996 John Wiley & Sons, Inc.

Truly chlorine-resistant polyamide reverse osmosis composite membrane

Truly chlorine-resistant polyamide reverse osmosis composite membranes were prepared by cross-linking the interface of the composite membrane. Such membranes possessed chlorine resistance one order of magnitude more than those of the commercially used polyamide composite membranes. The effect of the degree of cross-linking on chlorine resistance was also described. (C) 1996 John Wiley & Sons, Inc.

Syntheses and crystal structures of [(C6H5CH2C5H4)(2)GdCl center dot THF](2) and (C6H5CH2C5H4)(2)ErCl center dot THF

[(C6H5CH2C5H4)(2)GdCl . THF](2) (1) and (C6H5CH2C5H4)(2)ErCl . THF (2) were prepared by the reaction of LnCl(3) (Ln=Gd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, H-1 NMR, C-13 NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2(1)/c space group with a=1.1432(2), b=1.2978(2), c=1.7604(3) nm, beta=108.75(2), V=2.4732(9) nm(3), Z=2(four monomers), D-c=1.54 g . cm(-3). R=0.0342 and R(w)=0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P2(1)2(1)2(1) space group with a=0.8645(2), b=1.1394(3), c=2.5289(4) nm, V=2.4919(9) nm(3), Z=4, D-c=1.56 g . cm(-3). R=0.0514, R(w)=0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd3+ are located in the opposite direction (139 degrees); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er3+ are located in the same direction (6.5 degrees).

Chlorination and oxidation of aromatic polyamides .1. Synthesis and characterization of some aromatic polyamides

The synthesis is described of some aromatic polyamides based on unsubstituted, and methyl-, carboxy-, and sulfo-substituted diamines by interfacial polycondensation. Some of them are crosslinked and some of them contain heterocyclic aromatic rings. Their chemical structures are characterized by IR and C-13 solid-state NMR spectra and the spectra are interpreted. (C) 1996 John Wiley & Sons, Inc.

Preparation, structure and some physical properties of scheelite-related AgLnMo(2)O(8) compounds

We present the synthesis of the AgLnMo(2)O(8) oxides with Ln = La-Nd, Sm, Gd, Tb and Y. These compounds represent a scheelite-related structure type characterized by MoO42- tetrahedrons. The IR spectra show three transmittance bands in the region of 1000-400 cm(-1), which correspond respectively to the nu(1), nu(2), and nu(3) modes of the tetrahedral MoO42- groups. All of AgLnMo(2)O(8) are insulator materials at room temperature. The temperature dependence of the magnetic susceptibilities of AgLnMo(2)O(8) (Ln = Ce-Nd, Sm, Gd, Tb) show Curie-Weiss Law behaviors with two anomalies occurring at low temperature, whereas AgLaMo2O8 and AgYMo2O8 both exhibit diamagnetic properties as expected. The magnetic moments at room temperature fit very well with those corresponding to rare earth sesquioxides. This suggests that rare earth ions exist in +3 oxidation state in all AgLnMo(2)O(8) compounds.

Structure and luminescent properties of three new silver lanthanide molybdates

Three new compounds AgLnMo(2)O(8) (Ln = Eu, Gd, Tb) crystallize with a tetragonal scheelite-type structure characterized by MoO4 tetrahedra. The IR spectra show three absorption bands, which correspond respectively to the nu(1), nu(2), and nu(3) modes of the tetrahedral-MoO42- groups. The emission of AgGdMo2O8 shows the band of the MoO42- groups around 600 nm wavelength with very weak intensity. Both AgEuMo2O8 and AgTbMo2O8 emit intensely, and the concentration quenchings of both Eu3+ and Tb3+ luminescences are very weak. For all compounds, Ag+ luminescence is not observed. (C) 1996 Academic Press, Inc.

Copolymerization of styrene with butadiene and isoprene using a rare earth catalyst

In the copolymerization of styrene-butadiene and styrene-isoprene, a novel rare earth catalyst system (CF3CO2)(3)Ln/R(3-n)AlH(n)/(CH3)(3)CCH2Br (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; R = Me-, Et-, i-Bu-, and Oct-; n = 0 and 1) has been studied. The 1, 4 unit contents in the copolymers obtained are found to range from 64.4 to 99.6% with St contents of 5.2 to 59.9%, and intrinsic viscosities of 0.1 to 0.5 dl g(-1) measured by i.r., H-1 n.m.r. and C-13 n.m.r. spectra. From the calculated data of linked ratios, a change in the microstructure is induced by the styrene unit, probably adjacent to the butadiene or isoprene unit. An interesting result is that the ratios of styrene unit linked with 1, 2 or 3,4 units in the copolymers are far higher than in copolymers obtained with the nickel catalyst. The experimental results are discussed in terms of rare earth pi-allyl coordination and back-biting mechanism.

二烷基单硫代膦酸萃淋树脂吸附重稀土(Ⅲ)的研究

本文研究了Cyanex302萃淋树脂从硝酸介质中吸附重稀土（Ⅲ），吸附能力为Lu＞Yb＞Tm＞Er＞Ho＞Dy＞Tb＞Gd。考察了平衡水相酸度、稀土浓度、温度等对吸附平衡的影响。计算了重稀土（Ⅲ）间的平均分离系数β~z+1_z＝3．55，表明分离稀土（Ⅲ）的选择性优于HDEHP、HEH／EHP萃淋树脂，有可能用于制备高纯单一重稀土。Cyanex302萃淋树脂饱和吸附稀土（Ⅲ）的红外光谱表明，P＝S键参与了配位。