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101.
Franken A Kilner CA Thornton-Pett M Kennedy JD 《Chemical communications (Cambridge, England)》2002,(18):2048-2049
Reaction of the [1-Ph-closo-1-CB9H(4)-6,7,8,9,10-I5]- anion with 4-MeC6H4MgBr in the presence of [PdCl2(PPh3)2] gives the [Pd2I2(P(C6H(4)-4-Me)3)4]2+ salt of the [1-Ph-closo-1-CB9H(4)-10-I-6,7,8,9-(C6H(4)-4-Me)4]- anion, which exhibits an unusual neutral supramolecular assembly in the solid state, in which the dipalladium dication is encapsulated by two four-armed 'tetrapus' anionic units; the anion also has potentialities for four-fold dendrimer construction. 相似文献
102.
Janusz Z. Beer Kathleen M. Olvey Sharon A. Miller Delma P. Thomas Dianne E. Godar 《Photochemistry and photobiology》1993,58(5):676-681
The potential to induce non-nuclear changes in mammalian cells has been examined for (1) UVA1 radiation (340–400 nm, UVASUN 2000 lamp), (2) UVA + UVB (peak at 313 nm) radiation (FS20 lamp), and (3) UVC (254 nm) radiation (GI5T8 lamp). The effects of irradiation were monitored in vitro using three strains of L5178Y (LY) mouse lymphoma cells that markedly differ in sensitivity to UV radiation. Comparisons were made for the effects of approximately equitoxic fluences that reduced cell survival to 1–15%. Depending on the cell strain, the fluences ranged from 830 to 1600 kJ/m2 for the UVASUN lamp, 75 to 390 J/m2 for the FS20 lamp and 3.8 to 17.2 J/m2 for the G15T8 lamp. At the exposure level used in this study, irradiation with the UVASUN, but not the FS20 or G15T8, lamp induced a variety of non-nuclear changes including damage to cytoplasmic organelles and increased plasma membrane permeability and cell lysis. Cell lysis and membrane permeabilization were induced by the UVA1 emission of the UVASUN lamp, but not by its visible + IR components (>400 nm). The results show that the plasma membrane and other organelles of LY cells are highly sensitive to UVA1 but not to UVB or UVC radiation. Also UVA1, but not UVB or UVC radiation, causes rapid and extensive lysis of LY cells. In conclusion, non-nuclear damage contributes substantially to UVA cytotoxicity in all three strains of LY cells. 相似文献
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Abstract The effect of anion concentration on the apparent rate constant of polymerization kA p of isobutylene (IB) induced by the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl4 initiating system using the CH2Cl2/nC6H14 (60/40 v/v) solvent system at ?40 and ?80°C was studied by the use of nBu4NCl. Computer simulation has shown that kA p decreases several orders of magnitude upon the addition of even a very small amount of common anion TiCl?- 5 to the charge. The rate of change is reduced in the concentration range of experimental interest. It was concluded that the decrease of kA p with increasing TiCl ?- 5 concentration is mainly due to the decreasing contribution of propagation by free ions. The contribution (%) of propagation by free ions to the apparent rate of propagation was calculated. 相似文献
105.
Abstract The preparation and characterization of multiblock copolymers consisting of polyiso-butylene (PIB) soft segments connected to dimethyl terephthalate (DMT) plus 1,4-butane diol (BD) hard segments (PIB-b-PBT)n are described. Syntheses involved solution poly-condensation of DMT + BD + hydroxyl ditelechelic PIB (HO-PIB-OH). The overall block composition, and the lengths of the soft segments were varied in the Mn,PIB=1,400–10,000 g/mol range. The presence of PIB in the multiblocks was demonstrated. The solubility in THF and other solvents, and extractability of the polymers with n-hexane were studied. Efforts to determine solution viscosity remained unsuccessful due to the insolubility of the polar and nonpolar segments in a common solvent. Mechanical testing gave unacceptable results, however, the multiblocks showed good thermal stability (up to 367°C in air) and melt processibility appears to be feasible. 相似文献
106.
Madeleine A. Dallaston Christian J. Bettencourt Dr. Sharon Chow Joshua Gebhardt Jordan Spangler Dr. Martin R. Johnston Craig Wall Dr. Jason S. Brusnahan Prof. Craig M. Williams 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(41):9614-9618
Common oxidants used in chemical synthesis, including newly developed perruthenates, were evaluated in the context of understanding (and better appreciating) the sensitiveness and associated potential hazards of these reagents. Analysis using sealed cell differential scanning calorimetry (scDSC) facilitated Yoshida correlations, which were compared to impact sensitiveness and electrostatic discharge experiments (ESD), that enabled sensitiveness ranking. Methyltriphenylphoshonium perruthenate (MTP3, 8 ), isoamyltriphenylphosphonium perruthenate (ATP3, 7 ) and tetraphenylphosphonium perruthenate (TP3, 9 ) were found to be the most sensitive followed by 2-iodoxybenzoic acid (IBX, 2 ) and benzoyl peroxide (BPO, 10 ), whereas the most benign were observed to be Oxone ( 12 ), manganese dioxide (MnO2, 13 ), and N-bromosuccinimide (NBS, 17 ). 相似文献
107.
Alberto Hernn‐Gmez Emma Herd Eva Hevia Alan R. Kennedy Paul Knochel Konrad Koszinowski Sophia M. Manolikakes Robert E. Mulvey Christoph Schnegelsberg 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(10):2744-2748
The pivalates RZnOPiv⋅Mg(OPiv)X⋅n LiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt‐supported organometallic reagents, because apart from their effectiveness in Negishi cross‐coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X‐ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p‐tolyl case system shows that in [D8]THF solution these reagents exist as separated Me(p‐C6H4)ZnCl and Mg(OPiv)2 species. Air exposure tests and X‐ray crystallographic studies indicate that Mg(OPiv)2 enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p‐C6H4)ZnX (where X=different salts) with 4‐bromoanisole highlight the importance of the presence of Mg(OPiv)2. Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)2Li2(Cl)2(OPiv)2Zn]. 相似文献
108.
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110.
Low cost bifunctional initiators for bidirectional living cationic polymerization of olefins. I. isobutylene
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Turgut Nugay Balazs L. Keszler Tejal Deodhar Nihan Nugay Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》2017,55(22):3716-3724
We describe the discovery of novel low cost bifunctional initiators 2,4,7,9‐tetramethyl‐tricyclo[6.2.0.036]deca‐1(8),2,6‐triene‐4,9‐diol (bBCB‐diOH) and 4,9‐dichloro,2,4,7,9‐tetramethyl‐tricyclo[6.2.0.036]deca‐1(8),2,6‐triene (bBCB‐diCl), for living cationic bidirectional polymerization of olefins, for example, isobutylene. bBCB‐diOH was quantitatively synthesized in one step by UV radiation of commercially available diacetyl durene (DAD) and bBCB‐diCl by hydrochlorination of bBCB‐diOH. These molecules, in conjunction with TiCl4 coinitiator, initiate the living polymerization of isobutylene. Livingness was demonstrated by linear conversion versus molecular weight (MW) plots and narrow MW distributions. Polymerizations are slower than those initiated by the universally used “hindered” bifunctional initiator 5‐tert‐butyl‐1,3‐bis(1‐chloro‐1‐methyl)benzene and are suitable for rate studies. Herein, we report the synthesis, by the use of bBCB‐diCl, of relatively low MW (M n < 3000 g mol?1) allyl‐telechelic polyisobutylene (PIB) used for the synthesis of PIB‐based polyurethanes and that of relatively high MW (M n > 30,000) living PIB telechelics for the synthesis of thermoplastic elastomers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3716–3724 相似文献