Macroscopic helical and cylindrical morphologies from achiral 1,3-diynes

Diacetylenes containing an anhydride function (1) or two s-triazine groups (2) precipitate from organic solvents in large helical or cylindrical forms , respectively, which have been studied by optical and scanning electron mi croscopy. X-ray diffraction studies on helices of 10,12-tricosadynoic anhyd ride, {n-C10H21C C-C C(CH2)(8)CO}(2)O (1), show a lamellar crystalline phas e with layer spacing of 42.5 +/- 0.5 Angstrom and support a noninterdigitat ed bilayer structure. The crystal structure of a related amphiphilic diacet ylene, n-C10H21C C-C C(CH2)(8)CH2OSO2C6H4Me-4 (3), is also reported and dis cussed: triclinic, P (1) over bar, a = 5.9730(10) Angstrom, b = 8.0690(10) Angstrom, c = 29.524(3) Angstrom; alpha = 95.020(10)degrees, beta = 93.260( 10)degrees, gamma = 97.480(10)degrees. The nonamphiphilic, alpha,omega-difu nctionalized diacetylene, 6,6'-(deca-4,6-diyne-1, 10-diyl)di-2,4-di-amino-1 ,3,5-triazine, 2-{4,6-(NH2)(2)C3N3}(CH2)(3)C C-C C(CH2)(3)-{C3N3(NH2)(2)-4, 6}-2 (2), forms solid cylindrical particles of mean length similar to 0.5 m m, which may derive from helix formation. The origin of macroscopic chirali ty in the solid-state morphology of the achiral anhydride (1) is discussed.