Resorcinarene hexamers

Fig. 47 Energy minimised representation of a resorcinarene hexamer of 56 with encapsulated (C7H15)4N+Br. Reproduced with permission from [133], Copyright 2001 National Academy of Sciences, USA...

Fig. 5.15. Pyrogallarenes and resorcinarenes which form hexameric capsules through hydrogen bonding. The tetramethyl resorcinarene serves as a control compound. At the bottom, three different guest cations are shown, which carry charges to make the capsule MS-detectable. Right Computer model of the Ru(bpy)32 guest encapsulated in the cavity of the hexamer. Each monomer is shown with a different color. It can nicely be seen that the Ru complex not only fits size-wise, but also with respect to its symmetry and shape.

Prompted by its crystal structure [34a] and the fact that some of these aggregates were formed in water-saturated chloroform solutions, the role of the water molecules in the formation of the hexameric capsules of 15c and 16c was also studied. Diffusion NMR was selected since the chemical shift of water protons in the presence of acidic compounds is very sensitive to the amount of water, the concentration of the acidic material, the exchange rate and solvent pH and is therefore not a predictable parameter. In addition, since water molecules are very small relative to the resorcinarene and pyrogallolarene hexamers, the water diffusion coefficient was anticipated to be a rather sensitive parameter to follow water interaction with these supramolecular structures. Indeed, when the water diffusion coefficient was followed as a function ofthe I5C/H2O ratio, a decrease in the diffusion coefficient of the water peak was observed with the increase of the 15c/H2O ratio, as shown in Fig. 6.12. Fig. 6.12a-d shows the signal decay of the water (Fig. 6.12a, c) and the... 

Solvent molecules within the hexameric capsule can be displaced by sizable quaternary ammonium salts, and dissociation of at least one resorcinarene molecule from the hexamer is required for guest exchange. More details about the dynamic process of this assembly at nano- and micromolar concentrations were acquired using... 

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