The crystalline form of 2-(4'-cyano phenyl)-5-n heptyl-1,3 dioxane C18NO2H25 is orthorhombic and is assigned to space group P2(1)2(1)2(1) with four molecules per unit cell. The cell parameters are a = 5.5450(2) angstrom, b = 7.7334(3) angstrom, c = 41.0765(2) angstrom. D(calc) = 1.082 Mg . m-3. The structure was refined to an R = 0.07 for 840 counter intensities. The molecule is linear. The packing of the molecules shows a strong layered arrangement. This mesogenic compound exhibits a smectic phase in the range 53-55-degrees-C during heating and 55-42-degrees-C during cooling
