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Gareth J. Price Leanne Garland Jenny Comina Matthew Davis David J. Snell Peter J. West 《Research on Chemical Intermediates》2004,30(7-8):807-827
There is current interest in using high-intensity ultrasound to perform a range of chemical transformations, including polymerisation reactions. In this work, the technique of radical trapping, primarily using DPPH, has been used to measure radical production rates in a range of monomer and related systems when exposed to high intensity ultrasound. It has been shown that realistic rates of production can be obtained around room temperature equivalent to thermal decomposition rates > 100°C, making sonication a viable method for initiating polymerisation. Rates of initiation in a twophase organic in water system have also been measured. Some of the initiating species have been identified recording the ESR spectra of adducts with spin traps, although further analysis is needed before the complete range of radicals produced can be identified. 相似文献
994.
Amantia D Price C Shipman MA Elsegood MR Clegg W Houlton A 《Inorganic chemistry》2003,42(9):3047-3056
Dithioether- or diamine-tethered adenine derivatives react with Pt(II), Pd(II), and Rh(III) ions to give N3-coordinated complexes of the types [MCl(SSN)](+) (M = Pt or Pd), [RhCl(3)(SSN)], or [RhCl(3)(NNN)] (where SSN = 1-(N9-adenine)-3,6-dithia-heptane or 1-(N9-adenine)-4,7-dithia-octane; NNN = ethylenediamine-N,9-ethyladenine). Single-crystal X-ray analysis confirms the nature of the metal-nucleobase interaction and highlights a conserved intermolecular hydrogen-bonding motif for all the complexes, irrespective of the metal-ion geometry. Coordination significantly reduces the basicity of the adeninyl group, as indicated by a pK(a) value of -0.16 for [PtCl(N3-1-(N9-adenine)-3,6-dithia-heptane)]BF(4), compared to a pK(a) value of 4.2 for 9-ethyladenine. The site of proton binding, N1 or N7, could not be unambiguously assigned from the (1)H NMR data, because of the similar effect on the chemical shifts of the H2 and H8 protons. Density functional calculations at the BP-LACVP level suggest N1 as the site of protonation for this type of complex. This is in contrast to the N7-protonation reported for [Pt(dien)(N3-6,6',9-trimethyladenine)](2+), as reported elsewhere (Meiser et al., Chem.-Eur. J. 1997, 3, 388). However, further electronic structure calculations in the gas phase reveal that the preferred site for protonation for N3-bound complexes is conformationally dependent. N3 coordination was also found to reduce the extent of base pairing between adenine and thymine in dimethylsulfoxide for the self-complementary complex [PtCl(L3)](+) (L3 = 1-(N9-adenine)-3,6-dithia-9-(N1-thymine)nonane), compared to that for the uncomplexed ligand. 相似文献
995.
Seidel S Bionta RM Blewitt G Bratton CB Casper D Ciocio A Claus R Dye ST Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG LoSecco JM Matthews J Park HS Price L Reines F Schultz J Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R Thornton G van der Velde JC Wuest C 《Physical review letters》1988,61(22):2522-2525
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Abachi S Baringer P Bylsma BG DeBonte R Koltick D Low EH McIlwain RL Miller DH Ng CR Shibata EI Derrick M Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Blockus D Brabson B Brom J Jung C Ogren H Paik HW Rust DR Ackerlof C Chapman J Errede D Ken MT Meyer DI Nitz D Thun R Tschirhart R Neal H Cork B 《Physical review letters》1987,58(25):2627-2630
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