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51.
52.
Stulz E Scott SM Ng YF Bond AD Teat SJ Darling SL Feeder N Sanders JK 《Inorganic chemistry》2003,42(20):6564-6574
The synthesis of linear multiporphyrin arrays with mono- and bisphosphine-substituted porphyrins as ligand donors and ruthenium(II) or rhodium(III) porphyrins as ligand acceptors is described. With appropriate amounts of the building blocks mixed, linear dimeric and trimeric arrays have been synthesized and analyzed by (1)H NMR and (31)P NMR spectroscopy. The Ru/Rh acceptor porphyrins can be located either at the periphery or in the center of the array. Likewise, the monophosphine porphyrins can be positioned at the periphery, thus allowing a high degree of freedom in the overall composition of the arrays. This way, both donor and acceptor porphyrins can act as chain extenders or terminators. One of the trimeric complexes with two nickel and one ruthenium porphyrin has also been analyzed by X-ray crystallography. Attempts have also been made to synthesize higher order arrays by mixing appropriate amounts of the porphyrins; however, from the NMR data it cannot be concluded if monodisperse five, seven, or nine porphyrin arrays are present or if the solutions are composed of a statistical mixture of smaller and larger arrays. 相似文献
53.
Gáti T Simon A Tóth G Magiera D Moeller S Duddeck H 《Magnetic resonance in chemistry : MRC》2004,42(7):600-604
Adducts of four phosphine chalcogenides with the chiral dirhodium complex ([Rh-Rh]) were investigated by variable-temperature 1H and 31P NMR spectroscopy in order to compare their properties as axial ligands. Whereas the selenide (1) and the sulfide (2) are strong ligands with electrostatic attraction and, in addition, a significant orbital (HOMO-LUMO) interaction, the phosphine oxide compounds (P=O) bind primarily via electrostatic attraction and are relatively weak donors. Moreover, the overall bond strength in these adducts depends on steric congestion around the P=O group. 相似文献
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57.
Erich Metzger Roland Aeschimann Martin Egli Gaby Suter Ren Dohner Daniel Ammann Max Dobler Wilhelm Simon 《Helvetica chimica acta》1986,69(8):1821-1828
Lipophilic neutral carriers were synthesized which show Li+/Na+ selectivities of up to ca. 80 in highly lipophilic liquid membranes. The sensor membranes exhibit improved response times and increased lifetimes as compared to systems described earlier. They allow reliable measurements of Li+ in blood serum within the clinical concentration range. A 1:1 Li+/ionophore complex of one representative (N,N,N′,N′-tetracyclohexyl-5,5-dimethyl-3,7-dioxaazelaamide) has been prepared, and its structure was elucidated by X-ray analysis. 相似文献
58.
The interaction of AlR2(BHT)(OEt2) and AlMe(BHT)2 with methylmethacrylate (MMA) leads to the formation of the Lewis acid-base complexes AlR2(BHT)(MMA) [R = Me (1), Et (2)] and AlMe-(BHT)2(MMA) (3), respectively. The molecular structure of 1 has been determined by X-ray crystallography. The decrease in the C=O and C=C stretching frequencies in the IR spectrum, and downfield shift in the 13C NMR spectrum of the - and γ-carbons of the MMA, when compared to free MMA, is presented with respect to the activator ability of sterically crowded aryloxide compounds of aluminum to aluminum-porphyrin catalyzed (Inoue) polymerization of MMA. 相似文献
59.
The effect of gamma-irradiation on some new hydrazones of terpenoids using electron spin resonance (ESR) is reported. Gamma-irradiation of three derivates of hydrazone and of compounds resulting from the condensation of these derivates with terpenoids produces stable free radicals at room temperature. The analysis of the ESR parameters (g-factors and hyperfine coupling) and the simulation performed lead us to conclude that free radicals are of form R–N–NH2 (arising from hydrazine derivates) and R–N–N=R (arising from condensation compounds). The thermal stability of formed radicals is discussed and the activation energy involved in the process of recombination of free radicals is calculated. 相似文献
60.
Rabindra N. Roy Lakshmi N. Roy Jason G. Grant Mason P. Cummins Bennett J. Tabor III Sarah J. Richards Curtis A. Himes Bret R. Lively Penny L. Blackwell Ashley N. Simon 《Journal of solution chemistry》2002,31(11):861-872
The values of the second dissociation constant, pK
2, for the dissociation of the NH+ charge center of the zwitterionic buffer compounds 4-(N-morpholino)butanesulfonic acid (MOBS), and N-(2-hydroxyethyl)piperazine-N-4-butanesulfonic acid (HEPBS) have been determined from 5 to 55°C, including, 37°C at intervals of 5°C. The electromotive-force (emf) measurements have been made utilizing hydrogen electrodes and silver–silver chloride electrodes. The value of pK
2 for MOBS was found to be 7.702 ± 0.0005, and 8.284 ± 0.0004 for HEPBS, at 25°C, respectively. The related thermodynamic quantities, G
o, H
o, S
o, and C
p
o for the dissociation processes of MOBS and HEPBS have been derived from the temperature coefficients of pK
2. Both the MOBS and HEPBS buffer materials are useful as primary pH standards for the control of pH 7.3 to 8.6 in the region close to that of physiological fluids. 相似文献