Pyrogallol arene hexamers

Self-Sorting and Guest Affinity in Resorcin[4]arene and Pyrogallol[4]arene Hexamers... 

These FRET half-Uves were found to increase more dramatically with the increase in the concentration for pyrogaUol[4]arene hexamers than for the resor-cin[4]arene hexamers. In addition, the FRET experiments also corroborated what was previously known from diffusirMi NMR Pyrogallol[4]arene hexamers are more stable than resorcin[4]arene hexamers and form both in dry and in water-samrated organic solvents, whereas resorcin[4]arene hexamers rally form in water-samrated organic solvents [19, 20, 41]. These results showed that similar conclusions are reached from diffusion NMR [19, 20] and FRET experiments [41]. It should be noted that in the gas phase hetero-hexamers of resorcin[4]arenes and pyrogallol[4] arenes were found [30], a fact that is not easy to reconcile with solution data. In the gas phase, a charged ruthenium complex was added to the solution to allow detection of the hexameric capsule by the MS detector. This ruthenium complex could not be encapsulated in any of these hexamers in solution. In other dimeric cpasules, however, hetero-capsules are observed in solution. For example, heterodimers are observed in which resorcin [4]arene is, in fact, one panel of the heterodimer [42]. 

Figure 8 (a) General forumla for pyrogallol[4]arene, 7 (b) structure of the hexamer, 8, C-propylresorcin[4]arene with the oxygen atoms shown in red, (see also Plate 20). 

There has been a recent report of a very interesting, large supramolecular assembly related to the resorcin[4]arene work. The synthesis of several pyrogallol [4]arenes, 7, has been accomplished under mild conditions [32]. However, the authors report that they obtained the hexamer of C-isobutylpyrogallol[4]arene, 8, only one time out of many attempts (Figure 8). 

Fig. 31.6 Self-sorting in hexameric capsules Diffusion coefficients as a function of time and temperature for 1 1 mixtures of (a) 6d 7c, (b) 6d 6e, and (c) FRET pairs, (d) Schematic representation of the results showing that only homo-hexamers are formed when resorcin[4]arenes are mixed with pyrogallol[4] arenes [20d, 41]...

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