Faculté des sciences

Preparation of donor–acceptor substituted fluorostilbenes and crystal chemistry of fluorinated (E)-4-(4-halogeno-styryl)-benzonitriles

Mariaca, Raúl ; Labat, Gaël ; Behrnd, Norwid-Rasmus ; Bonin, Michel ; Helbling, Fabien ; Eggli, Patrick ; Couderc, Gaëtan ; Neels, Antonia ; Stoeckli-Evans, Helen ; Hulliger, Jürg

In: Journal of Fluorine Chemistry, 2009, vol. 130, no. 2, p. 175-196

The syntheses and crystal structures of a series of fluoro-substituted halogeno (Cl, Br, I)-cyano-stilbenes containing donor and acceptor groups (D-π-A) are reported. These molecules show a tendency to form antiparallel chain-like structures and herringbone packing, crystallising predominantly in a centric space group. However, second harmonic generation measurements bear evidence for... Plus

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    Summary
    The syntheses and crystal structures of a series of fluoro-substituted halogeno (Cl, Br, I)-cyano-stilbenes containing donor and acceptor groups (D-π-A) are reported. These molecules show a tendency to form antiparallel chain-like structures and herringbone packing, crystallising predominantly in a centric space group. However, second harmonic generation measurements bear evidence for orientational disorder leading to partial polar order below the ordinary X-ray structure determination limit. Some co-crystals are isostructural with their components. The non-fluoro as well as the halogeno-fluoro substituted components of co-crystals seem to impose their crystal structure on the complementary fluoro- or cyano–fluoro substituted components. Co-crystallization enhanced the deviation from centrosymmetry.