Fluorine anisotropy

Keywords Two-photon absorption Fluorescence anisotropy Fluorine derivatives Two-photon 3D data storage Two-photon dynamic therapy ... 

Although anisotropy of the chemical shift is expected for nuclei in non-cubic symmetry, the average value obtained for a polycrystalline solid should be comparable to these shifts for liquids, which are also average values. The chemical shift for concentrations of fluorine in the intermediate and on the high part of the concentration range of the samples examined was found to be (—40 40 ppm) relative to F (aqueous). No large shift for the fluoride ion occurs in the solids examined compared to the heavier halides in the solid state 118), indicative of the ionicity of the A1—F bond involved. 

A new class of liquid crystals with strongly negative dielectric anisotropy was explored by employing the ambivalent characteristics of the 1,3-dioxane moiety <2006EJ04819> due to both the polarity of 1,3-dioxane and axial fluorination, compounds 238-240 proved to have very useful mesogenic and electrooptical properties. 

It is our current opinion that all etching anisotropy or directionality is caused by energetic particle bombardment (primarily ions but in some cases, electrons). Other factors such as the degree of fluorine deficiency in the discharge can influence the... 

There has been an increasing interest in liquid crystals containing fluorine atoms because fluorination produces important changes in the melting temperatures, viscosity, birefringence, dielectric anisotropy and mesophase stability. This why structure-mesomorphism relationship studies were carried out in mono- and... 

Trifluoromethyl-substituted517 and perfluorophenyl-substitutedcarbocations518,519 have also been prepared and studied. Because of the relatively large fluorine chemical shifts, anisotropy and ring current effects play a relatively much smaller role than they... 

The use of fluorine labeled ligands or substrates allows one, via 19F NMR, to detect weak intermolecular interactions. One such technique (FAXS - Fluorine chemical shift Anisotropy and exchange for Screening) utilizes a fluorine-containing spy molecule to monitor changes in the transverse relaxation rate of the 19F resonance in the presence of a series of test compounds.43... 

Aromatic liquid crystals, such as compounds 106-109 collated in Table 3.10, have been investigated to a much lesser extent since they were perceived to be intrinsically more viscous than the analogous cyclohexane derivatives. This is indeed often the case. It was hoped that the incorporation of a fluorine atom in a lateral position of a polar compound, such as the ester (106), would create a nematic material, such as the esters (107 and 108), of positive dielectric anisotropy and low ratio of and Ae/sj.. Although this was partially... 

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