Curcuminoid-Based Responsive Surfaces for Fluorescent BF₃ Detection, a Fast and Reversible Approach

The strategic design of a novel curcuminoid (CCMoid), termed PA, containing pyrene units and a terminal carboxylic group provides the necessary tools for its efficient immobilization on surfaces and its potential use as an optical chemosensor. To this end, our work provides a robust methodology for the preparation of CCMoid-based active surfaces with a fluorescent response and reusability. The covalent immobilization of the CCMoid is obtained by the reaction of the acidic groups of PA and the imidazole ends of the previously functionalized substrates. In this way, fluorescent patterned surfaces of PA, whose emission could be observed in the visible region thanks to the pyrene groups of the CCMoid, were obtained using microcontact printing. In addition, the coordination of BF₃ molecules (in solution and in gas phase) with the keto-enol moiety of the PAs anchored on the surfaces has been analyzed. The ability of BF₃ to modify the optical properties of the CCMoids-based surfaces, leading to emissions in the near-IR, has been identified as a fast and reversible process. Such ability is intrinsic to the final coordinated system and not to other boron-based molecules, providing unique response and sensing surfaces.