Owing to their ability encapsulate a large range of guests, bowl-shaped molecules such as cyclodextrins and calixeranes have been widely exploited as receptors, sensors and catalysts. For the most part, receptor design has focused on the elaboration of basic existing structures, rather than on the creation of fundamentally new architectures. Unfortunately, few of these molecules lend themselves to modification in such a way that allows for the systematic variation of their size, shape and functionality.

Our approach to cavity design is based upon the synthesis of heptiptycene molecules. The simplest such heptiptycene, [1.1.1.1.1.1.1]-heptiptycene, is shown below. Also shown is its space filling model (center) and a map of its electrostatic potential (right, areas of high electron density are shown in red). This last picture indicates that heptiptycenes present considerable electron density to guests residing within their cavities. Thus, heptiptycenes are expected to make excellent receptors for both cations and aromatic molecules.

What makes iptycenes attractive is their potential for structural diversity. For example, shown below are a few members of the heptiptycene family:

Our modular synthesis allows us to readily synthesize cavities with different substituents(e.g. 1a-c) and with varying shapes (e.g. 2), depths (e.g. 3) and diameters (e.g. 4). With these receptors in hand, it will be possible to systematically study the effects these parameters have on the binding and catalytic properties of the cavities.