Molecular receptors for organic molecules are described in which calixarene is used as a molecular platform rather than for its cavity. This is illustrated by the synthesis of a receptor for barbiturates, a calixarene in a cone conformation containing two diaminotriazine moieties at the upper rim. This receptor (9) forms a molecular cleft in which phenobarbital complexes by hydrogen bonding both triazine rings. The association constant K is 520 M 1, when the self-association of the barbiturate is taken into account.
van Loon, J-D., van Loon, J-D., Heida, J. F., Verboom, W., & Reinhoudt, D. (1992). Calixarenes as building blocks for molecular receptors. Recueil des travaux chimiques des Pays-Bas, 111(7-8), 353-359. https://doi.org/10.1002/recl.19921110704