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161.
162.
Ugo Caruso Antonella De Maria Barbara Panunzi Antonio Roviello 《Journal of polymer science. Part A, Polymer chemistry》2002,40(17):2987-2993
Two formulas of grafted polymers with metal‐containing chromophores, potentially suitable for second‐order nonlinear optics applications, are described. Two chromophores were obtained from a tridentate ligand coordinated to Cu(II) or Pd(II) ions. The organometallic chromophore fragments were grafted to poly(4‐vinylpyridine) by the pyridinic nitrogen of the host polymer. Some qualities displayed by the new metallated polymers are remarkable: (1) a high value of the first hyperpolarizability coefficient of the chromophores, (2) a high content of the grafted chromophore in the polymers (up to 60 wt %), (3) a considerable increase in the glass‐transition temperatures (up to 240 °C), (4) good thermal stability in air (ca. 280 °C), and (5) good optical transparency of the films. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2987–2993, 2002 相似文献
163.
Reed M. Izatt Gypzy C. Lindh Peter Huszthy Glen A. Clark R. L. Bruening Jerald S. Bradshaw James J. Christensen 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(5):501-509
The macrocycle-mediated fluxes of alkali, alkaline earth, and several transition metal cations have been determined and compared in a H2O-CH2Cl2-H2O liquid membrane system using four water-insoluble macrocycles containing a dialkylhydrogenphosphate moiety. Transport of alkali metal cations by these ligands was greatest from a source phase pH = 12 or above into an acid receiving phase (pH = 1.5). Very low fluxes were observed for the transport of the alkaline earth cations and all transition metal ions studied except Ag+ and Pb2+ which were transported reasonably well by these new macrocycles.Deceased: September 5, 1987. 相似文献
164.
165.
M. Bešter-Rogač M. Tomšič J. Barthel R. Neueder A. Apelblat 《Journal of solution chemistry》2002,31(1):1-18
Conductivity measurements of oxalic acid and neutral oxalates (disodium oxalate, dipotassium oxalate, dicesium, and diammonium oxalate) were performed on dilute aqueous solutions, c < 3 × 10–3 mol-dm–3, from 5 to 35°C. These data and those available from the literature were analyzed in terms of dissociation steps of oxalic acid, the Onsager conductivity equation for neutral oxalates, the Quint–Viallard conductivity equation for the acid, and the Debye–Hückel equation for activity coefficients, to give the limiting equivalent conductances of bioxalate anion ;(HC2O4
–) and oxalate anion (1/2C2O4
2–) and the corresponding dissociation constants K
1 and K
2. 相似文献
166.
Fourier transform infrared reflection-absorption spectroscopy (FT-IRAS) has been used to study the orientation and coordination of glycine, L-phenylalanine and L-histidine on gold and copper surfaces. It was found that glycine and L-histidine were weakly adsorbed (physisorbed) in the zwitterionic form on gold. The surface chemical bonding of L-histidine and L-phenylalanine to copper were chemical rather than physical by nature. Conclusive evidence was obtained for coordination to copper through both the amino-nitrogen and carboxylate-oxygen atoms. 相似文献
167.
168.
169.
Noble metal nanoparticles were prepared by the in situ reduction of the respective metal salt precursors in the presence
of various protective polymers. Transmission electron microscopy (TEM) has been used to determine the particle shapes and
morphologies. These are strongly influenced by the reduction methods and conditions chosen, but the choice of the protective
polymer is equally important for controlling the particle morphologies and for the stabilization of the colloids. A whole
spectrum of nanoparticle morphologies and shapes was obtained, ranging from nanoagglomerates which are nevertheless well-defined
and well-stabilized to nanosized single crystals with triangular shape.
Received: 2 February 1998 Accepted: 29 May 1998 相似文献
170.
Yoshihiko Saito 《中国化学会会志》1991,38(5):405-424
A historical overview will be given on the structural studies on transition metal compounds and their interaction with other fields of coordination chemistry. About three decades have passed away since the structure and absolute configuration of tris(ethylenediamine)cobalt(III) complex ion were determined. At present accumulation of the structural data for isomers has enabled us to understand structural principles of chelate complexes in considerable detail. The energy minimization calculations can predict the detailed geometries of the complexes. Differences in thermodynamic properties between different conformers are well reproduced. Aspherical distribution of 3d electrons in transition metal complexes was detected for the first time in crystals of [Co(NH3)6][Co(CN)6] in 1973. Such an accurate electron density study provides important information on the d electrons placed in a ligand field. The high-spin and low-spin states can be distinguished unequivocally. In spite of a very small valence/total electron ratio, the asphericity of 4d and 5d electrons in a ligand field can be detected. The crystal structures of a series of dimeric copper(II) carboxylate adducts of the general formula [Cu(RCOO)2L]2 have been determined or redetermined as accurately as possible. The temperature dependent magnetic susceptibility of these crystals indicated that the isolated pairs of Cu(II) ions interact strongly through exchange forces. Molecular orbital calculations revealed that the electron population in the carbon atom of the bridging OCO group plays an important role in determining the strength of the spin superexchange interaction. In the crystals of some cobaloxime complexes, racemization of chiral groups bonded to Co proceeds on X-ray exposure without degradation of crystallinity. Several intermediate stages could be determined by X-ray analysis. Various reaction pathways were recognized and the reaction rate could be correlated with the atomic arrangement in the crystal. 相似文献