Supramolecular Nanostructures from Self-Assembly of T-Shaped Rod Building Block Oligomers

T-shaped coil-rod-coil oligomers, consisting of a dibenzo[a,c]phenazine unit and phenyl groups linked together with acetylenyl bonds at the 2,7-position of dibenzo[a,c]phenazine as a rigid segment have been synthesized. The coil segments of these new molecules composed of poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO) incorporating lateral methyl groups between the rod and coil segment and two flexible alkyl groups connecting with the rigid segment at the 4,6-position of dibenzo[a,c]phenazine, respectively. The experimental results reveal that the length of the flexible PEO coil chain influence construction of various supra-nanostructures from lamellar structure to rectangular columnar structure. It is also shown that introduction of different length of alkyl side chain groups in the backbone of the T-shaped molecules affect the self-organization behavior to form hexagonal perforate layer or oblique columnar structures. In addition, lateral methyl groups attached to the surface of rod and coil segments, dramatically influence the self-assembling behavior in the crystalline phase. T-shaped molecules containing a lateral methyl group at the surface of rod and PEO coil segments, self-assemble into 3D body-centered tetragonal structures in the crystalline phase, while molecules without a lateral methyl group based on PEO coil chain self-organize into 2D oblique columnar crystalline structures. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5021-5028