Novel oligothiophene-phenylamine based Schiff base as a fluorescent chemosensor for the dual-channel detection of Hg2+ and Cu2+ with high sensitivity and selectivity

•A new bifunctional fluorescent chemosensor 3TN bearing oligothiophene was developed.•3TN shows fluorescence “turn-on/turn-off” characteristic responses to Hg2+ and Cu2+.•The Hg2+/Cu2+ detection was highly reversible, selective and sensitive.•The response time to Hg2+/Cu2+ ions is less than 2 min.

A novel oligothiophene-phenylamine based Shiff-base 3TN was successfully developed as a dual fluorescent chemosensor for the rapid detection of Hg2+ and Cu2+ ions in THF/H2O (7/3, v/v) solution. Interestingly, 3TN upon interaction with various metal cations displays highly selective fluorescent turn-on response to Hg2+ and selective fluorescent turn-off response to Cu2+. The recognition process was highly reversible and completed within 2 min. The 1:1 binding modes (3TN/Hg2+ and 3TN/Cu2+) were proved by fluorescence measurements and FT-IR. Sensor 3TN also exhibits high anti-interference performance towards Hg2+/Cu2+ over other metal ions in a wide pH range. Moreover, the quite low detection limit was found to be 1.16 × 10−7 M for Hg2+ and 7.06 × 10−8 M for Cu2+. Therefore, these investigated results demonstrates that sensor 3TN has great potential to detect Hg2+ and Cu2+ ions in environmental analysis systems.

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