Engineering a single-benzene luminophore for acid/base responsiveness, crystal optical waveguiding, and amplified spontaneous emission

Due to their potential applications in optoelectronics, solid-state lasing, and bioimaging, organic luminophores have been extensively used as model systems for light matter interaction studies. Compact single-benzene luminophores capable of intense emission in both solution and solid states are promising dual-state emissive materials. Here, we design and synthesize a new fluorophore, wx-3, based on a single benzene framework. In wx-3, the electron density of the 2,5-diaminoterephthalate core (wx-4) is modulated by introducing an electron-withdrawing ester group at the γ-position. Compared with wx-4, wx-3 exhibits intensive green emission, large Stokes shift, and obvious luminescent responsiveness to acid-base stimuli in solution. In addition, the single crystals of wx-3 display obvious optical waveguiding property and the emergence of amplified spontaneous emission (ASE) also indicates that wx-3 is feasible as crystal laser medium. This work provides a rational molecular design concept for dual-state emission in single benzene systems which may have great potential in advanced optoelectronic and photonic devices.