A Surface Plasmon Resonance Investigation of the Selective Interaction of Organic Vapors with Cavitands

A class of supramolecules, called cavitands, that have been shown to exhibit discotic phases depending on the structure, are shown to have potential for sensing applications. Certain cavitands (macrocyclic compounds based on resorcinarenes) display selectivity of interactions with organic vapors. We use Surface Plasmon Resonance (SPR) to demonstrate this principle. The two cavitands chosen for this study, had both a different size and shape of the preorganized cavity and were exposed to a variety of aromatic and chlorinated hydrocarbons. QxCav-1 (cavitand) was found to have a marked preference for the aromatic compounds; with the sequence of selectivity, determined by SPR to be nitrobenzene > toluene > benzene. MeCav-2 (cavitand) on the other hand, showed higher selectivity to dichloromethane with respect to aromatic vapors at room temperature. Cavitands therefore represent attractive sensing materials, with potential for application in devices using optical transduction schemes based on a refractive index change.