RATIONAL DESIGN OF THE FIRST NONSPHERICAL DENDRIMER WHICH DISPLAYS CALAMITIC NEMATIC AND SMECTIC THERMOTROPIC LIQUID-CRYSTALLINE PHASES

The synthesis of the racemic AB(2) rodlike mesogenic monomer based on conformational isomerism, 13-hydroxy-1-(4-hydroxyphenyl)-2-(4-hydroxy- 4 ''-p-terphenylyl)tridecane (5), and the preparation via the converge nt approach of its first our generations of monodendrons and dendrimer s are described. All monodendrons and dendrimers exhibit thermotropic cybotactic nematic, smectic, and crystalline phases which are generate d from the anti conformation of the structural repeat unit derived fro m 5, and therefore, they do not exhibit a spherical shape. The depende nce of various transition temperatures on the generation number or on the molecular weight of these monodendrons and dendrimers follows tren ds similar to those of linear main chain liquid crystalline polymers c ontaining rodlike mesogenic units. However, at similar molecular weigh ts the viscosity of the nematic phase of these dendrimers is lower tha n that of the corresponding hyperbranched and linear polymers. This no vel class of liquid crystalline dendrimers opens many new synthetic, t heoretic, and practical opportunities in the fields of dendrimers and molecular, macromolecular, and supramolecular liquid crystals.