A novel imidazophenazine-based metallogel act as reversible H₂PO₄ ⁻ sensor and rewritable fluorescent display material

By rationally introduced 1H-imidazo[4,5-b]phenazine moiety into the gelator molecular, a novel organogelator G5 was designed and synthesized. Imidazophenazine moiety could act as fluorescent group as well as binding site. The gelator G5 could form a stable organogel (OG5) accompanied with dramatic aggregation-induced emission enhancement (AIEE) in DMF. The AIEE of OG5 could be quenched by adding Fe³⁺ into the OG5. Meanwhile, OG5 could form no fluorescence stable metallogel (FeG) with Fe³⁺. Interestingly, the metallogel (FeG) could reversibly fluorescent “turn-on” sense H₂PO₄ ⁻ with high selectivity and sensitivity. The detection limit of FeG for H₂PO₄ ⁻ is 1.0 × 10⁻⁶ mol L⁻¹, moreover, other ions did not interfere in the sensing process. The H₂PO₄ ⁻ sensing mechanism was confirmed based on competitive coordination between gelator, Fe³⁺ and H₂PO₄ ⁻. The metallogel FeG could act as reversible H₂PO₄ ⁻ sensor and convenient H₂PO₄ ⁻ test kits. In addition, the FeG film also could act as an rewritable fluorescent display material.