title: Discotic liquid crystalline poly(propylene imine) dendrimers based on triphenylene.
abstract: The design, synthesis, and mesomorphic properties of a new series of homodendrimers consisting of the commercially available poly(propylene imine) (PPI) dendrimers (G = 1-5), PPI-(NH(2))(n)() (n = 4, 8, 16, 32, 64), functionalized with a discotic triphenylene moiety are reported. The liquid crystalline behavior was investigated by means of differential scanning calorimetry (DSC), polarizing-light optical microscopy (POM), and X-ray diffractometry (XRD). All of the homodendrimers showed mesomorphic properties, with the second to fifth generations giving a hexagonal columnar mesophase (Col(h)) and the first generation a rectangular columnar mesophase (Col(r)). The X-ray study reveals that these mesophases show a highly ordered structure with segregation of triphenylenes and dendrimers into separate columns and a regular stacking distance inside the triphenylene columns. GPC analysis showed that the dendrimers had good monodispersity and MALDI-TOF studies of the first three generations gave good evidence that all of the terminal amino groups of the dendrimers were functionalized with a discotic unit.
authors.affiliation: Química Orgánica, Facultad de Ciencias - ICMA, Universidad de Zaragoza-CSIC, E-50009, Zaragoza, Spain.
authors.forename: Mark D
authors.initials: MD
authors.lastname: McKenna
authors.forename: Joaquín
authors.initials: J
authors.lastname: Barberá
authors.forename: Mercedes
authors.initials: M
authors.lastname: Marcos
authors.forename: José Luis
authors.initials: JL
authors.lastname: Serrano