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21.
Daniel E. Vicentes Andrea L. Romero Ricuarte Rodríguez Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(5):446-453
An efficient synthesis of 1‐arylisochromeno[3,4‐d][1,2,3]triazol‐5(1H)‐ones, involving the diazotization of 3‐amino‐4‐arylamino‐1H‐isochromen‐1‐ones in weakly acidic solution, has been developed and the spectroscopic characterization and crystal structures of four examples are reported. The molecules of 1‐phenylisochromeno[3,4‐d][1,2,3]triazol‐5(1H)‐one, C15H9N3O2, (I), are linked into sheets by a combination of C—H…N and C—H…O hydrogen bonds, while the structures of 1‐(2‐methylphenyl)isochromeno[3,4‐d][1,2,3]triazol‐5(1H)‐one, C16H11N3O2, (II), and 1‐(3‐chlorophenyl)isochromeno[3,4‐d][1,2,3]triazol‐5(1H)‐one, C15H8ClN3O2, (III), each contain just one hydrogen bond which links the molecules into simple chains, which are further linked into sheets by π‐stacking interactions in (II) but not in (III). In the structure of 1‐(4‐chlorophenyl)isochromeno[3,4‐d][1,2,3]triazol‐5(1H)‐one, (IV), isomeric with (III), a combination of C—H…O and C—H…π(arene) hydrogen bonds links the molecules into sheets. When compound (II) was exposed to a strong acid in methanol, quantitative conversion occurred to give the ring‐opened transesterification product methyl 2‐[4‐hydroxy‐1‐(2‐methylphenyl)‐1H‐1,2,3‐triazol‐5‐yl]benzoate, C17H15N3O3, (V), where the molecules are linked by paired O—H…O hydrogen bonds to form centrosymmetric dimers. 相似文献
22.
The recent fabrication of optical traps using super-continuum light impresses the need for a theory of inter-particle interactions under such conditions. Development of the theory provides a basis for calculation of the observations expected under experimental conditions. An expression for the inter-particle potential energy induced by continuum states of light is first derived using quantum electrodynamics. This energy expression is cast as a function of the spectral irradiance of the light, and the electric susceptibility of the interacting particles. Specific results are derived for light with a Lorentzian spectrum. It is shown that by filtering part of the spectrum, it is possible to exert control over the length of linear particle chains organized along the Poynting vector. The results exhibit scope for the optical fabrication of moldable structures using broadband light. 相似文献
23.
Andrs F. Yepes Ederson Jaimes Ali Bahsas Alirio Palma Michael B. Hursthouse Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(6):o284-o288
5‐Acetyl‐2‐chloro‐8,11‐dimethyl‐5,6,11,12‐tetrahydrodibenzo[b,f]azocine, C19H20ClNO, (I), crystallizes as a single fully ordered isomer, but 14‐acetyl‐8,11‐dimethyl‐7,8,13,14‐tetrahydrobenzo[f]naphtho[1,2‐b]azocine–14‐acetyl‐8,9‐dimethyl‐7,8,13,14‐tetrahydrobenzo[f]naphtho[1,2‐b]azocine (74/26), C23H23NO, (II), exhibits threefold whole‐molecule disorder involving both configurational and structural isomers. In (I) and in the predominant form of (II), the azocine rings adopt very similar conformations, forming boat‐shaped rings having approximate twofold rotational symmetry. There are no direction‐specific intermolecular interactions in the crystal structure of (I), but the molecules of (II) are weakly linked into chains by an aromatic π–π stacking interaction. The compounds were made under green conditions using an acid‐catalysed cyclization process having very high atom utilization. 相似文献
24.
Enantiomerically pure N-substituted epoxyalkene-2-azetidinones reacted with titanocene monochloride to give stereospecifically polyfunctionalized bicyclic beta-lactams. Four isomeric epoxyaldehydes 2 reacted with TiCp2Cl to give exclusively the respective carbacephams 7 while under the same reaction conditions the epoxyesters 1, which are more hindered for an intramolecular addition, gave the cyclization products 6 (only two isomers) and/or the elimination products 5 (all isomers). 相似文献
25.
Dislocation velocities in silicon in the experimental range of temperature and stress are studied a priori by combining a mechanistic treatment of elementary kink processes with activation energies obtained by atomistic calculations. Pronounced effects of intrinsic coupling of the dissociated partial dislocations are captured in kinetic Monte Carlo simulations, which are consistent with observed velocity variations with applied stress. As a result, the nature of "weak obstacles" to kink propagation, a long-standing postulate in previous data interpretation, is clarified. A striking new effect is predicted and offered for experimental verification when dislocation velocity shows nonmonotonic oscillatory behavior with increasing stress. 相似文献
26.
Tkaczyk S Tollefson K Tollestrup A Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Valls J Vejcik S Velev G Vidal R Vilar R Vologouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D 《Physical review letters》2000,84(6):1110-1115
We search for color singlet technirho and technipion production in p&pmacr; collisions at sqrt[s] = 1.8 TeV recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus E(T) and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane. 相似文献
27.
Toyoda H Trischuk W de Troconiz JF Tseng J Turini N Ukegawa F Vaiciulis T Valls J Vejcik S Velev G Vidal R Vilar R Volobouev I Vucinic D Wagner RG Wagner RL Wahl J Wallace NB Walsh AM Wang C Wang CH Wang MJ Watanabe T Waters D Watts T Webb R 《Physical review letters》2000,84(22):5043-5048
We report results from a study of events with a leading antiproton of beam momentum fraction 0.9057 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA. 相似文献
28.
Juan C. Castillo Rodrigo Abonía Michael B. Hursthouse Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(10):o495-o497
In the title compound, C23H22N4O, there is evidence for some bond fixation in the aryl component of the quinolinone unit. Pairs of molecules related by inversion are linked into R22(8) dimers by almost linear N—H...O hydrogen bonds, and dimers related by inversion are linked into chains by a single aromatic π–π stacking interaction. 相似文献
29.
An expression for the Casimir-Polder potential between molecules in a homogeneous dispersive and absorptive dielectric medium is derived. The effect of retardation on the interaction energy is discussed by examining the wave-zone and nonretarded limits of the potential. Unlike Lifshitz theory, the interaction energy is not derived from the potential between macroscopic bodies. In this work, a Green function that explicitly accounts for absorption in the medium is obtained. This function leads to possible dissipation effects and presents a near-zone form that vanishes in the limit of nonabsorptive medium. Employing a two-level model, it is shown that the retarded van der Waals dispersion potential in a medium may become repulsive as a consequence of absorption by the medium. It is suggested that the repulsive dispersion force may delay precipitation of nonpolar molecules from a dielectric solvent or even inhibit chemical reaction between them. 相似文献
30.
Trilleras J López LG Pacheco DJ Quiroga J Nogueras M Torre JM Cobo J 《Molecules (Basel, Switzerland)》2010,15(10):7227-7234
A series of pyrimido[4,5-b]quinolines (5-deazaflavines), were synthesized by microwave assisted intramolecular cyclization. The N?-substituted-2,4-diamino-6-chloro-pyrimidine-5-carbaldehydes, were prepared by selective monoamination of 2-amino-4,6-dichloropyrimidine-5-carbaldehyde with aliphatic and aromatic amines. 相似文献