@article {28607,
	title = {Synthesis and self-association of an imine-containing m-phenylene ethynylene macrocycle},
	journal = {J. Org. Chem.},
	volume = {67},
	number = {11},
	year = {2002},
	month = {2002 MAY 31},
	pages = {3548-3554},
	type = {Article},
	abstract = {The purpose of this study was to test the suitability of the imine bond as a structural unit within the backbone of phenylene ethynylene macrocycles and oligomers by determining the ability of m-phenylene ethynylene macrocycle 1 to form pi-stacked aggregates in both solution and the solid state. Macrocycle 1, with two imine bonds, was synthesized in high yield from diamine 4 and dialdehyde 5. The imine-forming macrocyclization step was carried out under a variety of conditions, with the best yield obtained simply by refluxing the reactants in methanol. The self-association behavior of 1 in various solvents was probed by H-1 NMR. The association constants (K-E) in acetone-d(6) and tetrahydrofuran-d(8) were determined by fitting the concentration-dependent chemical shifts with indefinite self-association models. The results showed that solvophobically driven intermolecular pi-pi stacking could be preserved in the imine-containing m-phenylene ethynylene macrocycles. Interestingly, in acetone macrocycle 1 exhibited a stronger tendency to form a dimer rather than higher aggregates. We postulate that this behavior may be due to electrostatic attraction between dipolar imine groups. The solid-state packing of 1 was studied by wide- and small-angle X-ray powder diffraction (WAXD and SAXD). Bragg reflections of 1 were consistent with a hexagonal packing motif similar to our previous studies on m-phenylene ethynylene macrocycles that formed columnar liquid crystal phases.},
	isbn = {0022-3263},
	url = {https://pubs.acs.org/doi/pdf/10.1021/jo010918o},
	author = {<strong>Zhao, Dahui</strong> and Moore, J. S.*}
}
