Aggregation feature of fluorine-substituted benzene rings and intermolecular C-H.F interaction: crystal structure analyses of mono- and trifluoro-L-phenylalanines.
X-Ray crystal structures of four different fluorine-substituted phenylalanines (two mono- and two tri-substitutions) were analyzed to investigate the effect of fluorine atom on the association pattern of benzene rings. Although respective structures showed similar molecular packing in such a way that the layers of hydrophobic benzene rings and hydrophilic amino/carboxyl groups were alternately running along a crystallographic axis, the association patterns of benzene rings were different depending on the substitution position and number of fluorine atoms. The general features could be that the partially displaced face-to-face interactions are increased with increase in the number of fluorine atoms, whereas the edge-to-face interactions are decreased. The C-H bond next to a fluorine-substituted carbon atom could serve as a donor of an intermolecular C-H.F hydrogen bond.
Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, Osaka, Japan. in@gly.oups.ac.jp
Yasuko
Y
In
Shouitirou
S
Kishima
Katsuhiko
K
Minoura
Takeru
T
Nose
Yasuyuki
Y
Shimohigashi
Toshimasa
T
Ishida
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D018360:Crystallography, X-Ray; D005464:Fluorobenzenes / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry*; D018179:Receptors, Thrombin / Q000187:drug effects
D005464:Fluorobenzenes; D018179:Receptors, Thrombin; D010649:Phenylalanine