Dynamic covalent synthesis of conjugated macrocyclic maleimides with interesting solvatochromic luminescent properties

Donor-acceptor (D-A) diaryl maleimides have received widespread attention due to their outstanding aggregation-enhanced emissive (AEE) properties. Herein, we report a novel rectangular D-A conjugated macrocyclic tetramaleimide with two phenyl and two 2,7-pyrene moieties as the sidewalls, while the maleimides as four corner linkers via dynamic and reversible Perkin reactions under thermodynamic control. Due to the sensitive D-A conjugation effects resulted from the multipole moments by four maleimides, such unique macrocycle exhibits unusual solvatochromic luminescent properties with a typical D-A charge transfer (CT) emission feature in the polar solvents, but pyrene-like emission characteristics in the nonpolar solvents regardless of the concentrations.