%0 Journal Article
%T A second polymorph of (2E)-1-(4-fluorophenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one
%A Jerry P. Jasinski
%A Ray J. Butcher
%A K. Veena
%A B. Narayana
%J Acta Crystallographica Section E
%D 2009
%I International Union of Crystallography
%R 10.1107/s1600536809028517
%X The crystal structure of the title compound, C18H17FO4, reported here is a polymorph of the structure first reported by Patil et al. [Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. A (2007), 461, 123¨C130]. It is a chalcone analog and consists of substituted phenyl rings bonded at the opposite ends of a propenone group, the biologically active region. The dihedral angle between the mean planes of the aromatic rings within the 4-fluorophenyl and trimethoxyphenyl groups is 28.7 (1)¡ã compared to 20.8 (6)¡ã in the published structure. The angles between the mean plane of the prop-2-ene-1-one group and the mean plane of aromatic rings within the 4-fluorophenyl and trimethoxyphenyl groups are 30.3 (4) and 7.4 (7)¡ã, respectively, in contast to 10.7 (3) and 12.36¡ã for the polymorph. While the two 3-methoxy groups are in the plane of the trimethoxy-substituted ring, the 4-methoxy group is in a synclinical [ sc =  78.1 (2)¡ã] or anticlinical [+ac = 104.0 (4)¡ã] position, compared to a +sc [53.0 (4)¡ã] or  ac [ 132.4 (7)¡ã] position. While no classical hydrogen bonds are present, weak intermolecular C¡ªH...¦Ð-ring interactions are observed which contribute to the stability of the crystal packing. The two polymorphs crystallize in the same space group, P21/c, but have different cell parameters for the a, b and c axes and the ¦Â angle. A comparison of the molecular geometries of both polymorphs to a geometry optimized density functional theory (DFT) calculation at the B3-LYP/6¨C311+G(d,p) level for each structure provides additional support to these observations.
%U http://scripts.iucr.org/cgi-bin/paper?S1600536809028517