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Assembly of Prussian blue analogue nanomaterials

University of British Columbia

Coordination polymers have many attractive properties but the development of applications has been hampered by the challenges associated with their processing and the preparation of nanosized analogues. In this thesis, the synthesis and characterization of new coordination polymer nanomaterials with previously inaccessible morphologies and compositions are reported. Prussian blue analogues (PBAs) were investigated as model compounds. Mesostructured PBAs were fabricated via a ligand-assisted liquid-crystal templating approach. Molecular surfactants having a charged iron cyanide complex as hydrophilic head group and metal-coordinated hydrophobic tails were synthesized. In formamide, the metal-containing template formed liquid-crystalline phases that were crosslinked into PBA mesostructures with the addition of transition metals. PBAs with well-ordered lamellar, hexagonal and cubic structures were obtained with a wide range of compositions. The materials made of iron(II) and iron(III) exhibited mixed-valency and ferromagnetic interactions in the PBA framework. A synthetic approach to attach a PBA precursor onto polymer-based structure-directing agents was developed. A preformed macromolecular backbone was functionalized with ionic pendent groups that can coordinate iron cyanide complexes. Metal-containing homopolymers and block copolymers were synthesized. In organic solvents, the ionic block copolymers behaved as a block ionomer and self-assembled into stable wormlike and toroidal reverse micelles whose cores were metallated with the iron cyanide complex or used as an ion confinement region for different cyanometallate compounds to be crosslinked into PBA-type frameworks. The soluble PBA nanomaterials are stable in solution, assemble into arrays on surfaces and were used as precursors for metal oxide nanostructures. Soluble hollow polymer capsules with PBA inner-shells were fabricated via emulsion-induced assembly of the iron cyanide block ionomer. The metal-containing amphiphilic macromolecules stabilized nanosized water droplets dispersed in organic solvent by assembling at the water-oil interface. The hydrophilic iron cyanide inner-shells were crosslinked into PBAs with zinc ions. The hollow capsules have selective permeability, are tunable in size, organize into hexagonal arrays in the solid state and were used as nanocontainers to encapsulate molecular compounds. A rigid structure-directing ligand was incorporated into the network of a PBA under solvothermal conditions to engineer the connectivity of a coordination polymer. A crystalline triptycene-scaffolded copper PBA was obtained.

Text

2011-10-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/33738

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/