Fluorine scanning

Insights from computational fluorine scanning, J. Am. Chem. Soc. 122 3909 (2000). 

J.A. Olsen, D.W. Banner, P. Seiler, U.O. Sander, A. d Arcy, M. Stihle, K. Muller, F. Diederich, A fluorine scan of thrombin inhibitors to map the fluorophilicity fluoropho-bicity of an enzyme active site Evidence for C-F- C = O interactions, Angew. Chem. Int. Ed. 42 (2003) 2507-2511. 

Synopsis of Kuhn and Kollman (2000) A Ligand Tliat Is Predicted to Bind Better to Avidin than Biotin Insights from Computational Fluorine Scanning . 

Fig. 8. Fluorine scans obtained by PIGE Fluorine-containing soil water enters the tooth mainly through the nerve canal into the pulpa. The cementum also readily takes up fluorine which slowly diffuses into the dentine, while the enamel crown forms a barrier. Fluorine enters a long bone as well from the periosteal surface as from the marrow cavity. The thickness of the bone wall does not influence the shape of the diffusion front itself, but limits the time window where age determination is possible, as the profile becomes flat much faster. (Human molar, Seeberg BE, Switzerland, 3750 bc, and human tibia, grave 132, Buren a. A. BE, Switzerland, medieval).

Table 1.7 summarizes systematic S AR studies of tricyclic thrombin inhibitors, rac-27 and rac-28, through fluorine scan to map the effects of fluorine introduction on... 

Olsen, J., Seiler, P., Wagner, B., et al. (2004) A fluorine scan of the phenylamidinium needle of tricyclic thrombin inhibitors effects of fluorine substitution on pKa and binding affinity and evidence for intermolecular C-F. .. CN interactions. Org. Biomol. Chem., 2, 1339-1352. 

Olsen, J. A., Banner, D. W., Seiler, P., et al. (2003) A fluorine scan of thrombin inhibitors to map the fluorophilicity/fluorophobicity of an enzyme active site evidence for C-F C=0 interactions. Angewandte Chemie International Edition, 42(22), 2507-2511. 

Kuhn B, Kollman PA. 2000. A ligand that is predicted to bind better to avidin than biotin insights from computational fluorine scanning. J. Am. Chem. Soc. 122 3909-16... 

The lubricant properties of alkanethiols and fluorinated alkanes have been studied extensively by scanning probe techniques [163]. In agreement with experiments on LB monolayers it was found that the fluorocarbon monolayers show considerably higher friction than the corresponding hydrocarbon monolayers [164, 165 and 166] even though the fluorocarbons are known to have the lowest surface free energy of all organic materials. 

Deoxyglucose labeled with fluorine-18 is commonly used in PET scans to locate tumors. Fluorine-18 has a half-life of 109 min. How long will it take for the level of fluorine-18 in the body to drop to 10% of its initial value ... 

A PET scan requires a substance called a tracer. A suitable tracer must accumulate in the target organ, and it must be modified to contain unstable radioactive atoms that emit positrons. Glucose is used for brain imaging, because the brain processes glucose as the fuel for mental and neural activities. A common tracer for PET brain scans is glucose modified to contain radioactive fluorine atoms. Our molecular inset shows a simplified model of this modified glucose molecule. 

The mounted samples were placed in the XPS vacuum chamber, and the chamber was evacuated prior to testing. The samples were exposed to the X-rays at 14.0 kV and 300 W. The approximate sampling area for the XPS is 1.0mmx3.5mm with a sampling depth of approximately 35.0 A at a 45° exit angle. Figures 16 and 17 show the survey scans from the epoxy and composite sample, respectively. Both show the presence of fluorine, which indicates the probable presence of a mold-release agent. 

Figure 13. Cyclic voltammogram of graphite (Lonza KS6, synthetic graphite) in 1 MLiCl04 in PC/novel fluorinated additive (90 10, v v) scan rate 30 pV s 1, Potentials vs. Li/Li+.

In 1994, we reported the dispersion polymerization of MM A in supercritical C02 [103]. This work represents the first successful dispersion polymerization of a lipophilic monomer in a supercritical fluid continuous phase. In these experiments, we took advantage of the amphiphilic nature of the homopolymer PFOA to effect the polymerization of MMA to high conversions (>90%) and high degrees of polymerization (> 3000) in supercritical C02. These polymerizations were conducted in C02 at 65 °C and 207 bar, and AIBN or a fluorinated derivative of AIBN were employed as the initiators. The results from the AIBN initiated polymerizations are shown in Table 3. The spherical polymer particles which resulted from these dispersion polymerizations were isolated by simply venting the C02 from the reaction mixture. Scanning electron microscopy showed that the product consisted of spheres in the pm size range with a narrow particle size distribution (see Fig. 7). In contrast, reactions which were performed in the absence of PFOA resulted in relatively low conversion and molar masses. Moreover, the polymer which resulted from these precipitation... 

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