摘要:

AbstractResolution of excess entropy of many types of transitions and estimation of standard entropy at 298.15K of compounds, for which experimental entropies have not yet been measured, depend on a reliable estimation of the lattice entropy. By taking into account the effects of cation mass and molar volume of the rare‐earth compounds, the following formula is proposed\documentclass{article}\pagestyle{empty}\begin{document}$$ S_{298.15}^0 = S_{{{\rm ref}}}^0 + \frac{3} {2}n_1 ^\prime\cdot R \cdot \ln \frac{M} {{M_{{{\rm ref}}} }} + \frac{3} {2}n_2 \cdot R \cdot \ln \frac{V} {{V_{{{\rm ref}}} }} $$\end{document}for the estimation of the lattice entropy of isostructural iso‐anionic rare‐earth compounds. We have investigated 32 compounds, and found good agreements between estimated and experimental entr

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020202

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractBy surface organic synthesis a Fe (III) tetra‐o‐aminophenyl porphyrin modified electrode was successfully prepared on glassy carbon electrode surface through amidization. The preparative conditions were investigated in detail. Using cyclic voltammetry and semidifferential neo‐polarography in an acidic aqueous solution the behavior of the catalytic reduction of oxygen on iron porphyrin modified electrode was studied. Based on experimental results it was shown that the irreversible process of 2‐electron‐reduction to hydrogen peroxide belongs to EC parallel catalyti

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020203

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe crystal of tetrahydrothiazole‐2‐thione (TTT) belongs to monoclinic system. Space groupP21/n.There are eight molecules in an unit cell with parametersa= 13.844(7)Å,b= 5.614 (2)Å,c= 13.516 (7)Å, β=95.08 (5)°,V=1046.3 (9)Å3The three dimensional intensity data were obtained on a Syntex R3 four‐circle diffractometer, and the number of the independent diffractions amounted to 1906.The structure was solved by direct method and refined by block‐diagonal least‐squares method. The finalRis 0.082. In crystal, the molecular structure is between 1 and 2 in which S(1), S(2), N and C(1) are coplanar with conjugation.We use CNDO/2 programmes written by ourselves on Eclipse computer to compute the electronic energies, molecular total energies, dipole moments, the charge densities and net charges of each atom of TTT and itsN‐benzoylated derivative.The color of the acylated TTT and its properties for aminoly

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020204

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe adsorption and micellar behavior of the mixed solutions of sodium perfluorooctanoate (7CFNa) and sodium decylsulfate (C10SNa) have been studied at constant ion strength of 0.1m. The adsorption was calculated from the surface (and interfacial) tension‐concentration curves by applying Gibbs equation. It was found that the cmc's of 7CFNa and C10SNa are of nearly the same value (1.66 × 10−2m and 1.45 × 10−2m, respectively), but γcmcof 7CFNa solution is ∼23 mNm−1, which is much lower than that of C10SNa solution. This implies that 7CFNa would have a much higher surface activity than C10SNa and be adsorbed preferentially; for instance, 7CFNa has a surface mole fraction of about 0.8 in the saturated adsorption layer of the 1:1 mixed solution. The mole fractions of 7CFNa at the surface are always greater than those in the bulk solutions. The adsorption at then‐ heptane‐aqueous solution interface is quite different from that at the air‐solution surface. Here C10SNa is preferentially adsorbed owing to “Mutual phobicity” between the HC‐chain ofn‐heptane and the FC‐chain of 7CFNa at the interface. All the cmc's obtained from the γ‐logmrelations of 7CFNa (or C10SNa) in the mixed solutions have nearly the same value and the cmc‐xcurves show a positive deviation from the ideal case. This further indicates that in the mixed solutions of fluorocarbon and hydrocarbon surfactants no completely miscible micelle but essentially the individual micelle of each surfactant exist due to the “Mutual phobicity” between FC‐ an

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020205

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe potential energy curve of MgH+ and the potential energy surface of Mg2H+ are calculated by quantum chemicalab initioSCF MO method with STO‐3G basis set. The electronic wave functions and populations are obtained. The eqilibrium internuclear distance of MgH+ is 1.60 Å. There are two possible configurations of Mg2H+:C ∞ candD ∞ h. The former is (Mg‐Mg‐H)+, with bond lengthrMg‐Mg= 2.41Å andrMg‐H =1.63Å. The latter is (Mg‐H‐Mg)+, with bond lengthrMg‐H = 1.73Å. The cause of the stability of these species is discussed. The result of calculation about the bond length of MgH+ agrees reasonably well with experimental value. The conclusion about the stability of (Mg‐Mg‐H)+ ion supports the hypothesis proposed by Porter, b

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020206

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe crystals of pentafluoropropionylbenzoylmethylene triphenylphosphorane that bears two strongly electron‐withdrawing groups in alkylidene moiety are monoclinic and its space group isC2/c, witha= 11.271(3)Å,b= 18.253(6)Å,c=23.938(7)Å, β = 91.09(2)°,z= 8. The X‐ray diffraction intensity data were collected on a four‐circle diffractometer. The structure has been solved by direct method and refined by block‐diagonal least‐squares method. The finalR‐ index was 0.075 for 3146 independent observed reflexions. In this paper the structure of this ylide is compared with that of corresponding arsonium ylide previously reported. Both ylidic skeleton structures are planar withsp2hybridization. The bond length of P‐C(1) is 1.748 (5)Å with bond order. 1.60 while the bond order of As‐C(1) in the corresponding arsonium ylide is 1.46, indicating that the phosphonium ylide has a greater contribution of “ylene” structure to the overall structure. As a result the phosphonium ylide should be less reactive than the corresponding arsonium ylide. In both ylides, (he major delocalized canonical forms of negative

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020207

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe formation constants (logK MAMAB) of ternary mixed ligand complex formed from 1,10‐phenanthroline (A, phen) andN‐(p‐substituted phenyl) glycines,RNHCH2COOH (B,pRPhG, CH3, H, CL), with copper (II), nickel (II), cobalt (II) and zinc (II) were determined by pH method at 25°C in 30% (V/V) ethanol solution in presence of 0.1MNaClO4. It was found that linear free energy relationships exist between the stability of M(II)‐phen‐p‐RPhG ternary complex and the base strengths of the ligandsp‐RPhG, conforming to the equation logK MAMA= αpKB+C. The factors influencing the stability of the ternary complex have been discussed. The enhancement of stability of ternary complex was explained in terms of formation of π back bonding between metal ion and the ligand phen. In contrast to the binary system, the ternary ni (II) and zn (II) complexes showed higher stability which could be accounted for by the formation of π back bonding and by intramolecular ligand‐ligand interaction, poss

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020208

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effects of different surfactants on the Hf‐quercetin, Zr‐quercetin, Sn‐morin, Mg‐oxine‐5‐sulfonic acid (H2QS), Zn‐H2QS, Cd‐H2QS and Tb‐EDTA‐sulfosalicylic acid (SSA) systems were investigated. It was found that the fluorescence intensity of each complex studied is greatly increased in the presence of a suitable surfactant. The optimum conditions for the formation of the ternary complexes involving a surfactant were found, and the compositions of these ternary complexes were established by fluorometry. In the presence or absence of a surfactant, the quantum efficiencies (ϕ) of fluorescent complexes were measured by the relative method, and their molar absorptivities at the excitation wavelength (ϵex) were calculated. It was found that the quantum efficiencies and molar absorptivities of fluorescent complexes were increased to various degrees because of the formation of the ionic associated complexes with fixed compositions, thus leading to greatly increased fluorescence intensity. The function of surfactant micelles and the relation between the molecular structures of surfactants and their effects on the fluorescent reactions were discussed. It is noted that only those surfactants with their aromatic system uncharged or unconnected directly with a charged functional group can sensitize the fluorescent reactions. By making use of the surfactant sensitization it is possible to develop some highly sensitive fluoro

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020209

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractA new type of macrocyclic polyethers has been synthesized. It consists of an azacrown ether as mother ring,e.g.1,7‐dioxa‐4,10‐diaza‐cyclododecane (1a) or 1,7,10,16‐tetraoxa‐4,13‐diazacycloocatadecane (1b), and two side chains attached on the two nitrogen atoms of 1a or 1b. A number of these new crown ethers are obtained by alkylation of the two secondary amino groups of 1a or 1b with corresponding halides, BrCH2(CH2OCH2)nCH2OR, in the presence of potassium carbonate. The crown‐alkali metal complex thus obtained is hydrolyzed by acid. In order to obtain pure crown ether the reaction mixture is treated with tetramethylammonium hydroxide and followed by solvent extraction.The ability of complexing alkali cations of macrocyclic polyethers in terms of the equilibrium constant have been studied by the method of solubilities of salts in chloroform. It is shown that the size of the mother ring, the number of oxygen atoms either in the ring or in the side‐chains, and the ionic radius of the alkali metal are the factors governing the stability of the metal complexes. Most of these new crown ethers possess high ability for alkali metal complexation some of them, such asN,N′‐ di‐β‐methoxyethyl‐1,7‐dioxa‐4,10‐diaza‐cyclododecanc (13a), possesses higher selectivity for Na+ and K+ ions than 18‐crown‐

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020210

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY

摘要:

AbstractThe electron impact mass spectrometric behavior of ten camptothecin analogs (1‐10) is described and discussed in detail with the aid of accurate mass measurement and metastable experimen

ISSN:0256-7660    

DOI:10.1002/cjoc.19840020211

出版商:WILEY‐VCH Verlag    

年代:1984

数据来源: WILEY