Fluorous effects

This fluorous effect can also be effective for the stabilisation of proteins. For example, the selective pairing of peptides which contain perfluorinated chains has been demonstrated, and perfluorinated amino acid side chains have been shown to stabilise the hydrophobic-driven folding of proteins [38,39]. 

K.H. Lee, H.Y. Lee, M.M. Slutsky, J.T. Anderson, E.N.G. Marsh, Fluorous effect in proteins De novo design and characterization of a four-ot-helix bundle protein containing hexafluoroleucine. Biochemistry 43(51) (2004) 16277-16248. 

Rule 4 The number of anti-fluorous functional groups capable of attractive in-termolecular interactions, via electrostatic forces, hydrogen bonds, or dispersion interactions must be minimized [16]. An example of such an anti-fluorous effect is the low fluorophilicity of hexafluorobenzene (12) and pentafluorobenzene (13) despite their high relative fluorine content. Both compounds can participate in specific electrostatic interactions with electron-rich hydrocarbons, for example the toluene component of the biphasic test mixture. 

Cametti M, Crousse B, Metrangolo P, Milan R, Resnati G (2012) The fluorous effect in biomolecular applications. Chem Soc Rev 41 31... 

Another spacer which was used to insulate the phosphorus atom from the electron-withdrawing effect of the perfluoroalkyl tail is the -0-(CH2) - spacer that contains an electron-donating oxygen atom directly attached to the aryl ring [25]. Fluorous derivatives of triphenylphosphine containing this ether spacer (13a-c) were prepared, though the lower coupling constant of cis-... 

---