Resorcin arene properties

Besides these covalently constructed cage-type receptors a number of self-assembled capsules with hydrogen bond donors protruding to the inside have also been described. An early example was reported by Atwood et al. This system makes use of the well known properties of resorcin[4]arene 30a and pyrogallol[4]arene 30b to form hexameric spherical capsules in the solid state and, in the case of 30b, also in solution. 

In this context the already extensive work of Rein-houdt and coworkers on the preparation and characterization of self-assembled monolayers of resorcin [4] arenes [11-13], calixarenes [14], and even carceplexes [15] constitutes one of the most important efforts to develop this field. Self-assembled monolayers of resorcin [4] arenes exhibit selective adsorption properties for small chlorinated hydrocarbons in the gas phase [13], although serious questions have been raised as to how much the observed selectivity has to do with the presence of molecular cavities in the monolayer assembly [16]. Davis and Stirling have also reported on the self-assembly of similar compounds and demonstrated the formation of multilayers [17,18]. The extensive and very systematic work of Crooks, Ricco and co workers on the development of devices for the detection of volatile organic compounds deserves special mention [19]. Recently, Crooks and coworkers have taken a very interesting turn in their work, demonstrating that monolayer-attached dendrimeric structures exhibit remarkable selectivity for the sorption of gas-phase molecules [20,21]. 

Overall, the hexameric resorcin[4]arene capsule showed very interesting selective properties for the condensation reaction between carboxylic acids and amines mediated by a cationic carbodiimide-based condensing agent similarly to what was observed in the previous case for the alkyne hydration reaction, the capsule prefers the encapsulation of smaller and more compact substrates that react faster than longer ones. 

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