An ortho-methylated fluorescent chemosensor based on pyrromethene for highly selective and sensitive detection of Ag+ and Hg2+ ions

•A new chemosensor based on the ortho-methylation of boron-dipyrromethene.•Fluorescent “turn-on” detection for HTM ions with high sensitivity and selectivity.•The detection upper limit for Ag+ is as low as 1.2 ppm.•The ortho-methyl group enhances the quantum efficiency and detection sensitivity.

A fluorescent chemosensor, ortho-methylated boron-dipyrromethene (o-MBDP) has been synthesized and characterized. It featured excellent selectivity and sensitivity for Ag+ and Hg2+ ions, which could enhance the weak fluorescence of o-MBDP drastically by several hundred times through coordination and as a result, behave as an efficient “turn-on” fluorescent probe. The detection upper limit for Ag+ ion could be decreased by at least one order of magnitude with the introduction of the ortho-methyl group, in comparison with analogous boron-dipyrromethene (BDP) sensors, indicating the feasibility in extensive application areas as chemosensors.

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