Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 11 (November 2008)

organic compounds

fg3060 scheme

Acta Cryst. (2008). C64, o616-o619 [ doi:10.1107/S0108270108033404 ]

Geometry and bond-length alternation in nonlinear optical materials. III. Structural parameters of two chromophores containing aromatizable donors

G. J. Gainsford, M. D. H. Bhuiyan and A. J. Kay

Abstract: The planar component of 2-{3-cyano-4-[3-(1-decyl-1,4-dihydroquinolin-4-ylidene)prop-1-enyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile, C₃₂H₄₆N₄O, (I), forms into layers parallel to the ( $\overline{1}$ 01) plane. The larger of the two spaces between layers is filled by the alkyl chains, giving a `sandwich stack' appearance. The packing of 2-{3-cyano-4-[5-(1-decyl-1,4-dihydroquinolin-4-ylidene)penta-1,3-dienyl]-5,5-dimethyl-2,5-dihydrofuran-2-ylidene}malononitrile, C₃₄H₃₈N₄O, (II), which has partial disorder in the 1-decyl group, utilizes weak C-HN, C-HO and C-N [pi] interactions in a three-dimensional `herring-bone' array with molecular segments parallel to the (111) and ( $\overline{1}$ 1 $\overline{1}$ ) planes. Different rotational isomers with respect to the polyene chain and the 5,5-dimethyl-2,5-dihydrofuran-2-ylidene link are observed in the two structures. The significance of the study lies in the delocalization of charge along the polyene chain and the supramolecular aggregation present, which highlight the difficulty in obtaining the noncentrosymmetric alignment required for high nonlinear optical (NLO) responses in zwitterionic chromophores.

Formula: C₃₂H₃₆N₄O and C₃₄H₃₈N₄O


	Structure factor file (CIF format) (391.5 kbytes) [ doi:10.1107/S0108270108033404/fg3060Isup2.hkl ] Contains datablock I

	Structure factor file (CIF format) (252.7 kbytes) [ doi:10.1107/S0108270108033404/fg3060IIsup3.hkl ] Contains datablock II

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