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TitleGeometry and bond-length alternation in nonlinear optical materials. I. Standard parameters in two precursors
Publication TypeJournal Article
Year of Publication2007
AuthorsGainsford, G.J., Bhuiyan M.D.H., and Kay A.J.
JournalActa Crystallographica Section C: Crystal Structure Communications
Paginationo633 - o637
Date Published2007
ISSN01082701 (ISSN)
KeywordsBond length, Bond-length variations, Crystal cohesion, Furanyl-idene ring, Geometrical optics, Hydrogen bonds, Molecular Structure, Nonlinear optics, Optical materials, Planar polyene chains
Abstract2-{3-Cyano-4-[4-(N-formyl-anilino)-trans-1,3-butadien-yl]-5,5-dimethyl-2, 5-dihydro-furan-2-yl-idene}propane-dinitrile, C22H18N4O2, (I), and 2-{3-cyano-4-[6-(N-formyl-anilino)-trans,trans-1,3,5-hexa-trien-yl]-5, 5-dimethyl-2,5-dihydro-furan-2-yl-idene}propane-dinitrile, C24H20N4O2, (II), show the alternating single/double-bond behaviour of push-pull chromophores. In the two structures, the planar polyene chains are twisted with respect to the furanyl-idene ring by 18.2 (2) and 12.4 (2)°, respectively. Comparison with structures of related and parent mol-ecules shows subtle but consistent bond-length variations consistent with charge-delocalized structures. Crystal cohesion is provided by various sets of hydrogen bonds, viz. C - Hmethyl⋯Ncyano and bifurcated (C=C - H)2⋯O=C in (I), and C - Hmethyl/phenyl⋯O and C=C - H⋯Ncyano in (II). © International Union of Crystallography 2007.

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