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61.
Simon J. Coles Michael B. Hursthouse 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):e405-e405
The molecular structure of the title compound, C14H14BrF3O2, adopts a bent conformation. Intramolecular O—H?F and intermolecular O—H?O interactions form a bifurcated hydrogen bond which produces a supramolecular assembly of head‐to‐tail dimers. 相似文献
62.
Frank Marken Yu-Chen Tsai Andrew J. Saterlay Barry A. Coles Daniel Tibbetts Katherine Holt Christiaan H. Goeting John S. Foord Richard G. Compton 《Journal of Solid State Electrochemistry》2001,5(5):313-318
Microwave activation of electrochemical processes has recently been introduced as a new technique for the enhancement and
control of processes at electrode|solution (electrolyte) interfaces. This methodology is extended to processes at glassy carbon
and boron-doped diamond electrodes. Deposition of both Pb metal and PbO2 from an aqueous solution of Pb2+ (0.1 M HNO3) are affected by microwave radiation. The formation of PbO2 on anodically pre-treated boron-doped diamond is demonstrated to change from kinetically sluggish and poorly defined at room
temperature to nearly diffusion controlled and well defined in the presence of microwave activation. Calibration of the temperature
at the electrode|solution (electrolyte) interface with the Fe3+/2+ (0.1 M HNO3) redox system allows the experimentally observed effects to be identified as predominantly thermal in nature and therefore
consistent with a localized heating effect at the electrode|solution interface. The microwave-activated deposition of PbO2 on boron-doped diamond remains facile in the presence of excess oxidizable organic compounds such as ethylene glycol. An
increase of the current for the electrocatalytic oxidation of ethylene glycol at PbO2/boron-doped diamond electrodes in the presence of microwave radiation is observed. Preliminary results suggest that the electrodissolution
of solid microparticles of PbO2 abrasively attached to the surface of a glassy carbon electrode is also enhanced in the presence of microwave radiation.
Electronic Publication 相似文献
63.
The dynamics of electric-field-induced lattice distortions and phase transitions in the BPI, BPII and BPIII (fog) phases of blue-phase mixtures, which include low-molar-mass and/or polymeric components, have been studied. Several electric-field-induced effects have been observed in the blue phases, and the electro-optic characteristics of the driven and non-driven responses of each are considered. Anomalous behaviour in BPIII, where driven response times were measured to be slower than the relaxation responses, is described and considered with respect to relaxation processes previously observed in BPII. Finally, we present data for a mixture containing 40 per cent by weight of a side-chain-polymer liquid crystal. In this case only BPI was observed, and it appears that the increased viscosity had little effect on the response times of the system. These data are discussed. 相似文献
64.
We show there is a computable linear order with a
initial segment that is not isomorphic to any computable linear order. 相似文献
65.
Microwave activation of electrochemical processes: enhanced electrodehalogenation in organic solvent media 总被引:2,自引:0,他引:2
Tsai YC Coles BA Compton RG Marken F 《Journal of the American Chemical Society》2002,124(33):9784-9788
The effect of high-intensity microwave radiation focused into a "hot spot" region in the vicinity of an electrode on electrochemical processes with and without coupled chemical reaction steps has been investigated in organic solvent media. First, the electrochemically reversible oxidation of ferrocene in acetonitrile and DMF is shown to be affected by microwave-induced thermal activation, resulting in increased currents and voltammetric wave shape effects. A FIDAP simulation investigation allows quantitative insight into the temperature distribution and concentration gradients at the electrode / solution interface. Next, the effect of intense microwave radiation on electroorganic reactions is considered for the case of ECE processes. Experimental data for the reduction of p-bromonitrobenzene, o-bromonitrobenzene, and m-iodonitrobenzene in DMF and acetonitrile are analyzed in terms of an electron transfer (E), followed by a chemical dehalogenation step (C), and finally followed by another electron-transfer step (E). The presence of the "hot spot" in the solution phase favors processes with high activation barriers. 相似文献
66.
Andrew J. Mountford Simon J. Lancaster Simon J. Coles 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(9):m401-m404
The title ionic solid, [Ti(C2H6N)3(C2H7N)2][Ti(C18BF15N)(C18H2BF15N)Cl(C2H7N)2]·C7H8, (I), comprises a cation with three dimethylamide ligands in the equatorial plane and two dimethylamine ligands positioned axially in a trigonal–bipyramidal geometry about the central TiIV atom. The anion has a highly distorted octahedral structure. The two dimethylamine ligands are coordinated mutually trans. The chloride is trans to the tris(pentafluorophenyl)boron–amide, while the sixth coordination site is occupied by an ortho‐F atom of the tris(pentafluorophenyl)boron–amide group in a trans disposition with respect to the tris(pentafluorophenyl)boron–nitride ligand. The most significant feature of the anion is the presence of an unprecedented terminal Ti[triple‐bond]N moiety [1.665 (2) Å], stabilized by coordination to B(C6F5)3, with a Ti[triple‐bond]N—B angle of 169.50 (19)°. 相似文献
67.
I.R. Butler L.J. Hobson S.J. Coles M.B. Hursthouse K.M. Abdul Malik 《Journal of organometallic chemistry》1997,540(1-2):27-40
The synthesis of a series of ferrocenylanthracene derivatives is described, utilising the palladium catalysed coupling reaction of 1,1′-bis(chlorozincio)ferrocene with halo-anthracenes. Bis-1,1′-(9-anthracenyl)ferrocene (1) was characterised by single crystal X-ray diffraction and shows an eclipsed ferrocenyl geometry. X-ray crystallographic studies indicate that there are no clear stacking interactions of either an intra- or intermolecular nature between the anthracenyl rings in the structure. A series of 9- and 10-disubstituted ferrocenylanthracene derivatives has also been prepared. In each case the palladium catalyst (Pd(dppf)Cl2) is recovered in a modified form, e.g. as the [(dppf)PdBr(9-anthracenyl)] complex in the synthesis of bis-1,1′-(9-anthracenyl)ferrocene. The single crystal X-ray structure of one such palladium complex [(dppf)PdBr-9-(10-chloroanthracenyl)] (15a) has been determined in a case where chloride/bromide exchange had occurred in the palladium complex intermediate. The potential application of compound 1 as synthon for the construction of a molecular sensing device is discussed. Cyclic voltammetry and fluorescence studies have been carried out for selected derivatives. 相似文献
68.
Clegg AD Rees NV Klymenko OV Coles BA Compton RG 《Journal of the American Chemical Society》2004,126(19):6185-6192
The validity of Marcus theory for outer-sphere heterogeneous electron transfer for the electro-oxidation of a range of anthracene derivatives in alkyl cyanide solvents is investigated. The precision measurement of these fast electron transfers (k(0) >or= 1 cm s(-1)) is achieved by use of the high-speed channel electrode and, where necessary, fast-scan cyclic voltammetry. First, the solvent effect on the rate of electron transfer is studied by considering the first oxidation wave of 9,10-diphenylanthracene in the alkyl cyanide solvents: acetonitrile, propionitrile, butyronitrile, and valeronitrile. Second, the variation of k(0) for a series of substituted anthracenes is investigated by analyzing the voltammetric response of the one-electron oxidations of 9-phenylanthracene, 9,10-dichloroanthracene, 9-chloroanthracene, 9,10-dicyanoanthracene, 9-cyanoanthracene, 9-nitroanthracene, 9,10-diphenylanthracene, and anthracene in acetonitrile. It is shown that the rate of electron transfer of a single compound in different alkyl cyanides is determined by the longitudinal dielectric relaxation properties of the solvent, while differences in rate between the substituted anthracenes in acetonitrile can be quantitatively rationalized by considering their relative hydrodynamic radii. This makes possible the accurate prediction of electron-transfer rates for a molecule by interpolation of rate constants known for related molecules. 相似文献
69.
A calix[4]arene-derived ditopic receptor 1 has been synthesized. In the absence of Na+, the receptor binds acetate in preference to diphenyl phosphate (as the tetrabutylammonium salts), but in the presence of Na+, the selectivity is reversed and the receptor, instead, binds diphenyl phosphate, and not acetate, which preferentially forms a salt ion-pair in free solution. [structure: see text] 相似文献
70.
Here we present the optic and electro-optic characteristics of ferroelectric dye guest-host devices incorporating different dye and S*C host materials. We demonstrate fast response time (< 100 μs) single polarizer and zero-polarizer device configurations for high order parameter dichroic dyes and single polarizer fluorescent dye devices. The dynamic data include measurements of response times as functions of voltage, temperature and dye concentration, from which we conclude that the inclusion of certain dyes does not adversely affect the ferroelectric phase. The contrast ratios of these novel guest-host devices are also presented and are shown, as expected, to be functions of tilt angle (and therefore temperature). However, we demonstrate that the high tilt angle of 45° is not necessary for high contrast devices, and in fact for certain devices configurations θ = 22½° is optimum. These results are discussed. 相似文献