Synthesis, Characterization, and Gas Permeation Properties

91
Chapter 3
dendrons (G1-a-ІІ–G1-c-ІІ) were prepared by the reaction of branched aliphatic acids
with 1,1′-carbonyldiimidazole, and subsequently with
N-(3-aminopropyl)propane-1,3-diamine generating a secondary amine at the focal
point (G1-a-І–G1-c-І), which upon further treatment with succinic anhydride afforded
a carboxyl moiety at the dendron termini. The second generation dendrons
(G2-a-ІІ–G2-c-ІІ) were prepared by the iteration of the same three-step reaction
sequence. 20 The presence of the branched alkyl periphery helps prevent the dendrons
from being insoluble in common organic solvents thus making the otherwise
cumbersome purification quite practicable, and the presence of carboxyl functionality
at the dendron termini renders them capable to be engineered for various applications.
Scheme 1. Synthesis of G1 and G2 Amide-Containing Dendrons. a
a Conditions: (a) toluene, 80 °C, 1 h; (b) toluene, 80 °C, 3 h; (c) toluene, 80 °C, 3 h;
(d) 1,1′-Carbonyldiimidazole, as in (a); (e) N-(3-Aminopropyl)propane
-1,3-diamine, as in (b); (f) Succinic anhydride, as in (c).