Self-assembled triphenylamine derivative for trace detection of picric acid

Detection of explosives is of utmost importance due to the threat to human security as a result of illegal transport and terrorist activities. Picric acid ( PA ) is widely used in the industrial and military fields, and is inadvertently able to contaminate the environment and groundwater, posing a threat to human health. Achieving the detection of explosives at the parts per billion ( ppb ) level using chemosensors is a great challenge. Herein, we demonstrate that triphenylamine based fluorescent chemosensors tris(4′-carbethoxybiphenyl) amine ( TCEPA ) and tris(4′-carboxybiphenyl) amine ( TCPA ) exhibit superior detection capability for PA in solution state at the ppb level (40 ppb and 5 ppb respectively) and efficient quenching behaviours in the vapor phase at room temperature. In addition, fluorescent test strips have been prepared by dip-coating Thin Layer Chromatography ( TCL ) for trace detection of PA at the attogram level.