NMR diffusion measurements on 10 different multicomponent hydrogen-bonded assemblies, viz. the three single rosettes SR1-SR3 (13·2a3, 13·2b3, 13·2c3) the double rosettes DR1-DR5 (3a3·2a6, 3b3·2b6, 3c3·2a6, 3d3·2a6, 3e3·2a6), and DR6 (4a3·16), and the tetrarosette TR (53·2a12) are described. Some of the above rosettes have been previously identified as well-defined assemblies (viz. SR1, DR1-DR3, and TR) using established characterization techniques (1H NMR spectroscopy, X-ray diffraction, and MALDI-TOF MS after Ag+-labeling). The diffusion coefficients of these assemblies were studied and used as a reference for the identification of three new assemblies (DR4-DR6), the characterization of which could not be established unequivocally using other characterization tools. A good correlation was found between the experimental and calculated diffusion coefficients when DR1 was used as a reference. A relatively good correlation was obtained between the effective hydrolytic radii calculated from the diffusion data and those extracted from gas phase-minimized structures with SR1 and DR2 being exceptions. The diffusion measurements show that assembly DR4 is a thermodynamically stable species, while assemblies DR5 and DR6 are less stable and only present to a minor extent.
|Number of pages||13|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|Publication status||Published - Oct 2000|
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