GROWTH HABITS AND MECHANISM OF SEVERAL PO LAR ORGANIC-CRYSTALS IN VARIOUS SOLVENTS

Growth habits of several polar organic crystals with a structure A-C6H 4-D such as 4 - amino - 4' - nitrodiphenyl sulfide (ANDS), o - dicyano vinyl anisole (DIVA), N - 4 - nitrophenyl - (L) - prolinol(NPP) and 2- methyl-4-nitroaniline (MNA) depend strongly on the solvents from which they are grown. An incorporation model of polar growth units has been proposed to qualitatively explain the observed growth forms, which wa s based on: (1) the influence of the interaction between the solvent m olecules and the growth units on the structural forms of the growth un its; and (2) the interaction between the solvent molecules and the gro wth interfaces, particularly two polar faces for polar organic crystal s. Since these interactions strongly affect the incorporation rates of the growth units on the positive and negative faces, a variety of the crystal habits such as polar growth, needle habits or platelet forms appear, and thus a good explanation for the observed habits in various solvents is expected to be obtained.