Novel Fluorophore-ureido-calix[5]arene receptors fir the recognition of bioactive guests

Fluorescence stands out as a powerful tool for designing chemosensors, mainly due to its remarkable sensitivity, enabling the detection of chemical species even at nanomolar concentrations. Supramolecular chemistry-based sensing offers advantages like selective and specific design, leveraging the complementarity of size, shape, and function between the receptor and the analyte. Among macrocycle hosts, Calix[5]arenes are effective receptors for recognizing linear alkylammonium ions and biogenic amines. The efficiency of this recognition process depends on the ion pair interaction between ammonium cation heads and their counterions. To enhance this, we propose two novel fluorophore-ureido-calix[5]arene luminescent receptors for detecting bioactive species. These receptors combine the known complexing abilities of calix[5]arenes with the synergistic action of the ureido group to trap anionic counterions. Functionalization with chromophore molecules, covalently linked to the calix[5]arene scaffold, allows these receptors to use fluorescence spectroscopy to monitor the complexation of guests containing linear alkylammonium structural units.