Design and property investigation on a five-interaction-based fluorescent anion receptor clip

A molecular clip combining a doubly substituted fluorescent anion-π donor probe and two flexible arms bearing H-bond motifs constitutes a new generation of anion receptors. Five simultaneous non-covalent interactions are highlighted by theoretical complexation studies with five different anions. A large range of analytical techniques (electrospray-tandem mass spectrometry, NMR, UV-Visible, steady-state as well as time-resolved fluorescence) was deployed to evaluate the stoichiometry and association constants with the selected anions. The photophysical and anion-π donor properties of the tetrazine ring allowed fine characterization of the binding properties of the ligand. Based on previously published results, an anti-cooperativity effect in non-covalent interactions was demonstrated.