Liquid crystalline oligo(p-phenylene vinylene)-terminated poly(propylene imine) dendrimers : synthesis and characterization

Different generations of poly(propylene imine) dendrimers modified peripherically with urea oligo(p-phenylene vinylene)s (OPV) having a 3,4,5-tri(dodecyloxy)phenyl mesogenic unit (OPV-dendrimers) were successfully synthesized and fully characterized. Although intramol. H-bonding exist between the urea linkages of the end groups, only weak interactions between the p-conjugated segments were obsd. in soln. The hydrogen-bonding interactions increased for higher generation dendrimers due to the closer proximity of the end groups, indicative of a more dense-shell packing. All generations of OPV-dendrimers showed liq. cryst. behavior in which the OPV-dendrimers have a homeotropic orientation. The temp. range of the liq. cryst. phase increased with higher generation. [on SciFinder (R)