A new fluorescent and colorimetric probe for trace hydrazine with a wide detection range in aqueous solution

• A new fluorescent and colorimetric probe with strong ICT effect.
• Significant fluorescence enhancement and changes in color toward hydrazine.
• High sensitivity at ppb level with a detection limit lower than that regulated by EPA.
• Wide range detection resulted from large conjugated system.

A new fluorescent and colorimetric probe based on the reaction and intramolecular charge transfer (ICT) effect is designed and synthesized. The probe responds rapidly toward hydrazine and exhibits distinct color changes from yellow to colorless, indicating its use as a color indicator for hydrazine. Moreover, the probe also shows a significant broad band fluorescence (410–700 nm) enhancement by ∼120-fold after the addition of hydrazine. With a detection limit as low as 0.11 ppb, the probe can detect hydrazine in a wide concentration range because of the blunted sensing functional group. The contrast test shows almost no interruption from common elements in water, suggesting the high selectivity of this probe toward hydrazine. The theoretical calculation based on density functional theory (DFT) is also performed and two different ICT modes are found. This hydrazine probe would be a promising candidate applicable in environment protection, water treatment and safety inspection.