A new sensitive and selective detection of Ga 3+ by thiophene-based 'turn-on' fluorescent chemosensor.

We designed a thiophene-based fluorescent chemosensor DHTC ((E)-2-([3,5-dichloro-2-hydroxybenzylidene]amino)thiophene-3-carboxamide) for detecting gallium (Ga 3+ ). DHTC could probe Ga 3+ using fluorescence enhancement. The limit of detection for Ga 3+ by DHTC was 0.39 μM. The binding mode of DHTC to Ga 3+ was determined as a 1:1 ratio from analysis by Job's plot and electrospray ionization-mass spectrometry (ESI-MS). In addition, DHTC could selectively detect Ga 3+ using test kits. The sensing process of Ga 3+ by DHTC was presented using ultraviolet-visible light titration, Job's plot, ESI-MS, 1 H nuclear magnetic resonance titration, and density functional theory calculation.