Molecular Recognition of Spermine using Aggregation-Induced Emission

In this communication we report the synthesis and characterisation of a novel dianionic compound with aggregation-induced emission properties. This compound was able to recognize spermine via a multivalent electrostatic interaction leading to a restriction of intramolecular rotation enhancing the fluorescence emission. This recognition was investigated in detail using UV-Vis and fluorescence spectroscopy. Furthermore the binding stoichiometry was determined via isothermal titration calorimetry. Besides that the structure of the compound was confirmed by X-ray crystallography. To proof the bivalent binding a singly negatively charged control compound was synthesized showing no specific interaction with the amines screened. Theoretical calculations were performed to get a deeper insight in the molecular structure and the electronic transitions.