The role of Li-O bonds in calculations of nonlinear optical coefficients of LiXO3-type complex crystals

The second-order nonlinear optical (NLO) tenser coefficients of LiXO3 (X = I; Nb or Ta) type complex crystals have been calculated using the chemical bond theory of complex crystals. Contributions of each type of bond to the total second-order NLO coefficient d(ij) and the linear susceptibility X are quantitatively determined. All tensor values thus calculated are in good agreement with experimental data. The Li-O bonds are found to be an important group in the contributions to the total NLO tenser coefficient, especially for those in LiNbO3 and LiTaO3. The importance of Li-O bonds depends on the environment of Li atom in these crystals.

An electrochemical study of prussian blue microcrystallines mixed in PEO400 polymer electrolyte by solid-state voltammetry

The electrochemistry of Prussian blue mixed in a polymer medium containing MClO4 (M = Li+, Na+, K+, TBA(+)) as the supporting electrolyte was studied by means of solid-state voltammetry. This approach is new in Prussian blue studies. The behavior of PB in polymer electrolytes is somewhat similar to the well-known behavior for an electrochemically synthesized PB film in aqueous media. Besides, K+, Li+ and Na+ ions can also transport through the crystal of PB because of its zeolitic nature. The transport of TBA(+) ions is possible. Kinetic control lies in the diffusion of cations in and out of the lattice of Prussian blue. Reduction waves of Prussian blue depend on both the size and type of cations. PB is very stable upon electrochemical cycling in polymer electrolytes and air. This system may be used in rechargeable batteries and electrochromic devices.

Study of molecular order in organo-soluble polyimide thin films

The changes in refractive indices (n(TE) and n(TM)) in a direction normal to the plane of thin films of an organo-soluble polyimide based on 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride and 2,2'-dimethyl-4,4'-methylene dianiline were measured by a prism coupler. The results implied that the molecules near the substrate-polyimide interface were much ordered, while those near the polyimide-air interface were less ordered, judging from the variation in the level of negative birefringence with the depth of the films. The molecules are more condensed near the substrate surface, as seen by the average refractive index increasing from the polyimide-air interface to the substrate-polyimide interface, which implies that the condensed states of polyimide molecules change gradually in the depth direction. (C) 1997 Elsevier Science B.V.

Lanthanide ions for the hydrolysis of 5'-mononucleotides and 3'-mononucleotides

Cleavage of adenosine-5'-monophosphate (5'-AMP), guanosine-5'-monophosphate (5'-GMP), adenosine-3'-monophosphate (3'-AMP) and guanosine-3'-monophosphate (3'-GMP) by lanthanides was investigated by NMR and the method of measuring the liberated phosphates. Rapid cleavage of both 5'-mononucleotides and 3'-mononucleotides by Ce-III and Ce-IV under air at pH 9 and 37 degrees C was observed. Other lanthanides showed less efficiency for hydrolyzing 5'-mononucleotides but 3'-mononucleotides were catalyzed by a range of lanthanide ions. The mechanism for hydrolyzing 3'-mononucleotides by lanthanides was:investigated. The notable difference in reactivity between Ce-III and the other lanthanide ions under air was further studied showing that the cleavage is enhanced with increasing molar fraction of Ce-IV. The fast cleavage of mononucleotides by Ce-III under air at pH 9 is ascribed to the resultant Ce-IV in the reaction mixture. (C) 1997 Elsevier Science Ltd.

Bilayer formation of two chiral ferroelectric liquid crystal molecules at the air-water interface

The bilayer formation behavior of two chiral ferroelectric liquid crystal molecules at the air-water interface was studied.

The synthesis of dendrimers bearing alkyl chains and their behavior at air-water interface

A new kind of amphiphilic polyether dendrimer bearing eight alkyl chains at the periphery were synthesized step by step using the convergent method. Their structures were confirmed by FT-IR spectra, H-1 NMR spectra and mass spectra etc. The pi-A isotherms, hysteresis and molecular area-time curves at air water interface were reported. These results showed that they could form stable monolayers at water surface.

Al-Li-Ymm合金的组织和腐蚀性能

对Al-3.1Li及Al-2.7Li-0.21Ymm二种合金的铸态及在540℃条件下固溶处理４小时后的组织进行了观察和分析，测定了二种合金在3.5%NaCl水溶液中的电化学腐蚀性能。结果表明：二种合金的宏观组织未见明显示差别，含Ymm的合金微观组织较细化，添加少量Ymm对合金的腐蚀性能有较好的影响，固熔处理后的合金耐腐性能提高

Synthesis of lanthanide-alkylaluminium bimetallic complexes and studies on their catalytic activities for polymerization of some polar monomers

Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes with the formula [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AIR(2) . 2THF](2) (Ln = Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF,CO,), (Ln=Nd, Y) with HAI (i-Bu)(2) and of Eu(CF3CO2)(3) with AlEt(3), respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(mu-CF3CO2)(2)Nd (mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Nd-Al) and [(mu-CF3CO2)(2)Y(mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Y-Al) are isomorphous and crystallize in space group with a=12.441(3) Angstrom [12.347(5) Angstrom for Y-Al], b=12.832(3) Angstrom [12.832(4) Angstrom], c=11.334(3) Angstrom [11.292(8) Angstrom], alpha=104.93 (2)degrees [104.45(4)degrees], beta=98.47(2)degrees [98.81(4)degrees], gamma=64.60(2)degrees [64.30(3)degrees], R=0.519 [0.113], R(w)=0.0532 [0.110], Z=1 and [(mu-CF3CO2)(2)Eu(CF3CHO2)AlEt(2) . 2THF](2)(Eu-Al) in space group P2(1)/n with a=11.913(6) Angstrom, b=14.051(9) Angstrom, c=17.920(9) Angstrom, alpha=101.88(11)degrees, beta=gamma=90 degrees, R=0.0509, R(w)=0.0471 and Z=2. The six CF3CO2- (including CF3CHO2-) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO2- type coordinated to two different Ln; (B) the two oxygen atoms in the second of CF3CO2- type coordinated to Ln and Al, respectively; (C) one of the two oxygen atoms in the third CF3CO2- type bidentately coordinated to two Ln and another oxygen coordinated to Al and one of the two Ln, respectively. Unlike types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp(3)-hybridized configuration rather than an sp(2)-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO2- ligand. Methyl methacrylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence of a small amount of ECH.

Studies on porphyrin and phthalocyanine monolayers by means of compression-recompression isotherms and BAM

Monolayers of porphyrin and phthalocyanine at the air-water interface were studied by means of film balance and Brewster angle microscopy (BAM). Results showed that the final point of compression isotherm and that of recompression isotherm were coincident or not coincident depending on the target pressures. Results were discussed in terms of the morphology of monolayers observed by BAM.

Hydrolysis of adenosine monophosphate and guanosine monophosphate by lanthanides

The hydrolysis of adenosine-5'-monophosphate(5'-AMP) and guanosine-5'-monophosphate(5'-GMP) by lanthanides was investigated. 5'-AMP and 5'-GMP was efficiently hydrolyzed by cerium(III) chloride under air at pH 9 and 37 degrees C, and other lanthanides (III) showed less efficiency at the same condition. The hydrolysis rate of 5'-AMP by cerium was greater than that of 5'-GMP. UV spectra showed that Ce(III) was oxidized to Ce(IV) in the reaction mixture. The active species for the hydrolysis of 5'-AMP and 5'-GMP was ascribed to the Ce(IV) hydroxide cluster in the reaction mixture.

Efficient cleavage of ribonucleoside 3',5'-cyclic phosphates and deoxyribonucleoside 3',5'-cyclic phosphate by lanthanides

The cleavage of 3',5'-cAMP, 3',5'-cGMP and 3',5'-dcAMP by lanthanides has been investigated by HPLC and H-1 NMR. Rapid cleavage of cAMP, cGMP and dcAMP by Ce(III) under air at pH 8 and 37 degrees C has been observed. Regioselective cleavage of P-O(5') bond in cAMP, cGMP and dc;aMP tu give the corresponding 3'-AMP, 3'-GMP and 3'-dAMP by lanthanide chlorides has been achieved, and 3'-AMP and 3'-GMP are cleaved to adenosine(A) and guanosine(CT) more slowly, respectively, The notable difference in reactivity between Ce(III) and the other lanthanide ions under air has also been studied. The cleavage is enhanced with the increase in the molar fraction of Ce(IV). The fast cleavage of cAMP by Ce(III) under air at pH 8 is ascribed to the resultant Ce(IV) in the reaction mixture.

甲烷氧化偶联Ti-La-Li系多元氧化物催化剂的表面碱性和表面活性氧种

利用CO2-TPD方法考察了Ti-La-Li系多元氧化物催化剂的表面碱性,实验发现:C2 选择性与表面碱强度呈顺变关系,而CH4 转化率与CO2 的脱附峰面积呈顺变关系.同时,利用XPS,O2-TPD等方法对该体系催化剂的表面活性氧种进行了表征与研究,结果表明:催化剂的表面晶格氧与C2 选择性有关,表面吸附氧与甲烷转化(包括偶联和深度氧化)有关.O2 -TPD实验发现催化剂的表面存在三种氧:α( 100℃≤t≤450℃),β(450℃

TRIS(TERT-BUTYLCYCLOPENTADIENYL)NEODYMIUM-MU-CHLORO-TRIS(TETRAHYDROFURAN)LITHIUM, [ND(ETA(5)-(T)BUCP)3(MU-CL)LI(THF)3]

The title complex, tris[2(eta5)-tert-butylcyclopentadi-enyl]-mu-chloro-1:2kappa2Cl-tris(tetrahydrofuran-1kappaO)lithiumneodymium, [Nd(C9H13)3(mu-Cl)Li(C4H8O)3], consists of the neutral moiety ((t)BuCp)3Nd linked to the cation [Li(thf)3]+ by a mu-Cl bridge

SYNTHESIS AND CRYSTAL-STRUCTURE OF [LI(THF)4][((T)BUCP)YB(NPH2)3]

The title complex [Li(THF)4] [(tBuCp)Yb(NPh2)3] was synthesized by the reaction of t-butylcyclopentadienyl ytterbium dichloride with 2 equivalents of LiNPh2 in THF, hexane, and toluene at -78-degrees-C. The complex was characterized by elemental analysis,

Study of Methane Oxidative Coupling over Ti-La-Li Mixed Oxides

The composition and structures of Li-Ti-La mixed oxides as well as their catalytic activity for methane oxidative coupling have been studied by means of XRD XPS, IR, SEM and so on. The results indicate that by changing x value in Li-La1-xTixO2 oxides phas