A new detection scheme for catecholamines was constructed through embedding synthetic receptors within vesicles comprising phospholipids and polydiacetylene. Fluorescence emission of the polydiacetylene was induced through specific interactions between the soluble ligands and the vesicle-incorporated hosts. The system demonstrated remarkable selectivity among structurally similar ligands and achieved much lower detection thresholds compared to that of other reported catecholamine sensors. The chromatic assembly provides a generic route for high sensitivity detection of ligand-receptor interactions.

In spite of their key role in signal transduction, the mechanism of action of adrenergic receptors is still poorly understood. We have imitated the postulated binding pattern of the large membrane protein with a small, rationally designed synthetic host molecule. Experimental evidence is presented for the simultaneous operation of electrostatic attraction, hydrogen bonds, π stacking, and hydrophobic interactions. By virtue of this combination of weak attractive forces, adrenaline derivatives in water are bound with high shape selectivity for the slim dopamine skeleton. We think that these findings support the postulated cooperative interplay of noncovalent interactions in the natural receptors. In addition, they provide access to a new type of adrenaline sensor. This may be the first step towards an artificial signal‐transduction system.

A new rationally designed receptor molecule binds adrenaline derivatives in water. Its binding pattern (see picture) imitates the interplay of noncovalent interactions operating in the natural receptor. High shape selectivity is achieved for the slim dopamine skeleton, and leads to rejection of substrates with an α‐substituent, such as amino acid derivatives.

The macrocyclic bisphosphonate 2 forms complexes with amino alcohols, amines, and amino acid esters with high association constants in polar organic solvents. Exertion of solvophobic interactions inside the macrocyclic cavity in DMSO and methanol leads to specificity for guest molecules with hydrophobic moieties. Experimental evidence is presented for the insertion of the guest molecules' nonpolar groups into the macrocycle's hydrophobic cavity. NMR spectra of complexes with 2 in DMSO show a molecular imprint of the guest molecule; this gives information about its location inside the macrocycle. In aqueous solutions strong self-association of 2 occurs, which is explained by distinct structural similarities between 2 and micelle-forming phospholipids.

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