Conjugated poly(aryleneethynylenesiloles) and their application in detecting explosives

Hyperbranched and linear conjugated polysiloles incorporating arylene ethynylene subunits (6 and 7) were synthesized by the Sonogashira reaction. The two polymers possess unusual phenomena of PL, with gradual addition of water in their THF solution, the intensity of PL firstly increased and then decreased, this may be due to the aggregate-enhanced emission (AEE) effect and aggregation-caused quenching (ACQ) effect. The polymers function as sensitive fluorescent chemosensors for the detection of explosives, such as picric acid (PA) and TNT. The quenching constants of 6 for PA and TNT were 4.7 x 10(-2) ppm(-1) and 4.6 x 10(-3) ppm(-1), respectively. The quenching constants of 7 for PA and TNT were 8.6 x 10(-2) ppm(-1) and 6.5 x 10(-3) ppm(-1) respectively. The polymer 7 has more detective efficiency for PA and TNT than that of polymer 6, this may be due to the less steric hindrance.