STRUCTURE OF A NEW BIFORKED MESOGEN DERIVED FROM 3-(3,4-DIALKYLOXYPHENYL)-PROPANOIC ACID

p-Phenylenebis(methyleneamino-p-phenyl) bis{3-[3,4-bis(tridecyloxy)phenyl]propanoate}, C90H136N2O8, monoclinic, M(r) = 1374.0, P2(1)/c, a = 53.518 (4), b = 8.407 (1), c = 9.244 (2) angstrom, beta = 93.39 (1)-degrees, V = 4152 angstrom 3, Z = 2, D(x) = 1.098 Mg m-3, lambda(Cu K-alpha) = 1.5402 angstrom, graphite monochromator, mu = 0.484 mm-1, F(000) = 1508, T = 298 K, R = 0.074 for the 2560 observed reflections. The molecules adopt a zigzag form: the polyaromatic central moiety of the molecule is 36.2 angstrom long; the two alkyloxy chains are stretched (ttt) and approximately parallel to the xy plane; both chains make an angle close to 120-degrees with the central moiety. Molecules form sheets of about 53 angstrom thickness and are arranged as in a smectic C mesophase; the central cores make a tilt angle of 60-degrees with the normal to the sheet and are quasiparallel to the xz plane; interactions between sheets are very weak in the 0x direction. An explanation is given of the transition between the crystalline arrangement of the molecule and the hexagonal symmetry of the mesophase for this compound.