UBC Theses and Dissertations
Construction of nanofibers from supramolecular self-assembly of Schiff-base macrocycles and metal salphen complexes Hui, Joseph
The work described in this thesis mainly covers the investigations of a series of conjugated Schiff-base macrocycles and metal salphen complexes. These compounds self-assemble into supramolecular structures through electrostatic or metal-ligand interactions, and their morphologies were studied by electron microscopy and atomic force microscopy. The Schiff-base macrocycles can bind alkali metal and ammonium cations into their crown-ether interior, leading to the formation of one-dimensional columns that can further organize into nanofibers with hierarchical organization. However, when macrocycles appended with long alkoxy chains were treated with the same conditions, lyotropic liquid crystallinity in organic solvents was observed under a polarized optical microscope. Among the metallosalphen complexes prepared, zinc(II)-containing salphen complexes were found to assemble into helical fibrous structures and exhibit gelation behavior in various solvents. Furthermore, modification of the peripheral substituents of the zinc(II) salphen complexes with carbohydrates further enhanced the helicity in the nanofibers. In addition, the surface texture and diameter of the nanofibers can be altered by the presence of ditopic 4,4′-bipyridine and the increase in hydrophobic effects during sample preparation.
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