title: Packing conflicts in the Z' = 5 structure of CF(3)(CF(2))(3)(CH(2))(10)COOH.
abstract: Dimers of the partially fluorinated amphiphile 1-(perfluorobutyl)undecanoic acid, CF(3)(CF(2))(3)(CH(2))(10)COOH, crystallize in the same basic packing arrangement found for many n-alkyl carboxylic acids. The unit cell of the fluorinated compound, however, contains five independent molecules rather than the one found for most n-alkyl carboxylic acids including CH(3)(CH(2))(13)COOH. The structures of the two C(15) acids are compared. The structural modulations that lead to the large value of Z' can be understood as resulting from the conflict between the necessity of filling space densely and uniformly and the tendency of unlike groups to be segregated spatially. The few other known structures of compounds with both (CF(2))(n) and (CH(2))(m) regions show evidence of the same conflict.
authors.affiliation: Department of Occupational and Environmental Health,100 Oakdale Campus, 124 IREH, The University of Iowa, Iowa City, IA 52242-5000, USA.
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Lehmler
authors.forename: Sean
authors.initials: S
authors.lastname: Parkin
authors.forename: Carolyn Pratt
authors.initials: CP
authors.lastname: Brock
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D005227:Fatty Acids / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure
chemical_list: C488181:1-(perfluorobutyl)undecanoic acid; D005227:Fatty Acids; D005466:Fluorocarbons; D006845:Hydrocarbons, Fluorinated; C117025:pentadecanoic acid