Porous materials are applicable to nanofluidics, to catalysis, and to gas storage and can be used as controlled nanoenvironments to stabilize reactive species or facilitate selective reactions. Our group has focused on macrocyclic building blocks that are constructed from urea groups and organic C-shaped spacers. These building blocks are remarkably robust and assemble in high fidelity. Simple 1-dimensional channels are advantageous for studying basic processes of transport and diffusion. This talk explores the optimal design of these building blocks and examines the applications of these homogeneous channels as confined environments for photocycloadditions and polymerization reactions. Small pores and channels offer a handle for influencing selectivity of reactions performed in their nanoenvironments. The ~ 4.5 Å diameter channels of pyridyl-phenylethynylene bis-urea macrocycles facilitated the photoinitiated and stereoselective oligomerization of isoprene to afford trans-1,4 polyisoprene with low dispersity. The larger ~ 9 Å diameter channels of the assembled phenylethynylene bis-urea macrocycles were able to absorb a wide range of coumarin, chromone, substituted styrene and vinyl-pyridines. UV-irradiation of these host-guest complexes induced selective photodimerizations and polymerizations in these nanochannels.

Functional materials from self-assembled bis-urea macrocycles

253rd National Meeting (2017)

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