- Surfactant and Hydrophobic Derivatives of trans-Stilbenes as Probes of Vesicle and Micelle Solubilization Sites. Studies Using Fluorescence and Photoisomerization as Probes
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An investigation of the fluorescence and photoisomerization of several surfactant trans-stilbene derivatives in aqueous micelles and vesicles is reported.The temperature dependence of Φf was determined for several media over the range 5-70 deg C.The results present a picture of similar micellar solubilization sites for the trans-stilbene chromophore in every case; the micelle is "seen" by the stilbene as a moderately viscous fluid medium with slightly higher values for Φf and slightly reduced Φt->c compared to nonviscous homogeneous solutions.For vesicles considerably more complex behavior is observed.Generally Φf is considerably higher than in solution and Φt->c is much lower.Several, but not all, of the surfactant and hydrophobic stilbenes show a sharp sensitivity in Φf as a function of T when passing through Tc, the vesicle phase transition temperature.Arrhenius plots for the process competing with fluorescence as a function of temperature show relatively high values for Ea and log A, above Tc, consistent with the high temperature phase providing a microenvironment for the stilbene chromophore like a viscous solvent.Below Tc, the variation of Φf gives much lower values for EA and log A which suggest escape from the fluorescence state is "order limited" rather than viscosity dominated.These results suggest that the low-temperature phase of vesicles presents an environment for the stilbene chromophore more like an inclusion complex than a fluid medium.The effect of cholesterol addition on DODAC vesicles containing the stilbenes is to increase fluidity below Tc and to effectively increase viscosity above Tc.
- Suddaby, Brian R.,Brown, Patti E.,Russell, John C.,Whitten, David G.
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- Making a difference on excited-state chemistry by controlling free space within a nanocapsule: Photochemistry of 1-(4-alkylphenyl)-3-phenylpropan-2-ones
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The free space within a reaction cavity plays a determining role during the excited-state reaction of 1-(4-alkylphenyl)-3-phenylpropan-2-ones included within a capsule formed by two molecules of a deep cavity cavitand. By controlling the free space within the reaction cavity through remote alkyl substitution on the reactant ketone it is possible to control the yield of the rearrangement product shown above.
- Sundaresan, Arun Kumar,Ramamurthy
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p. 3575 - 3578
(2008/02/12)
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- Odorless substitutes for foul-smelling thiols: Syntheses and applications
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Several alkanethiols and p-alkylphenylmethanethiols were synthesized, and their odors were compared with those of ethanethiol and benzyl mercaptan by human and instrumental sensors. Among the various thiols analyzed, 1-dodecanethiol (1) and p-heptylphenylmethanethiol (3) were revealed to be odorless. 1-Dodecanethiol (1) has been used instead of ethanethiol for dealkylation of ethers, and p-heptylphenylmethanethiol (3) can replace benzyl mercaptan in the preparation of a 1,3-mercapto alcohol from an α,β-unsaturated ketone. These odorless thiols will greatly improve the physical environment of the researcher working with these foul-smelling compounds.
- Node, Manabu,Kumar, Kamal,Nishide, Kiyoharu,Ohsugi, Shin-Ichi,Miyamoto, Tetsuo
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p. 9207 - 9210
(2007/10/03)
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- Synthesis and antirhinovirus activity of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)-9H-purines
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A series of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)purines was synthesized and tested for antirhinovirus activity. Most of the compounds were synthesized by alkylation of 6-chloro-2-(trifluoromethyl)-9H-purine with the appropriate benzyl halide followed by displacement of the chloro group with dimethylamine. Alternatively, 6-(dimethylamino)-2-(trifluoromethyl)purine was alkylated with the appropriate benzyl halide. Although several different aryl substituents provided compounds with IC50's = 0.03 μM against rhinovirus serotype 1B, no congener was significantly more active than the parent 2. Twenty-three compounds were tested against 18 other serotypes, but none exhibited a uniform profile of activity.
- Kelley,Linn,Selway
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p. 1757 - 1763
(2007/10/02)
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