A highly sensitive and selective naked-eye probe for detecting copper ion based on 2,3-modified Bodipy derivatives

• A molecular probe BNP based on 2,3-modified boron-dipyrromethene (Bodipy) derivatives toward copper ion was synthesized.
• The probe BNP treated with Cu2+ in H2O/DMSO displays remarkable solution color change from the light yellow to purple, which is further confirmed by TD-DFT calculations.
• The low naked-eye detection limit (2.5 μM) and real-time detection for Cu2+ give the possibly direct detection by the naked eyes.

A molecular probe BNP based on 2,3-modified boron-dipyrromethene (Bodipy) derivatives, with high sensitivity and selectivity toward copper ion, was designed and synthesized. The probe treated with Cu2+ in aqueous solution (H2O/DMSO 60/40) displays obvious absorption alternation with maximum red-shift from 525 nm to 554 nm and gives correspondingly remarkable solution color change from the light yellow to purple. The theoretical calculation (TD-DFT) further demonstrates the absorption red-shift of BNP with addition of Cu2+. The 1:1 stoichiometry binding mode of BNP toward Cu2+ is determined by the study of Job plot and MALDL-TOF mass. The probe BNP has strong affinity (the stability constant Ks = 2.1 × 106 M−1) and the low detection limit (0.53 μM) toward Cu2+. The low naked-eye detection limit (2.5 μM) and real-time detection give the possibly direct detection by the naked eyes. These results extend the application of 2,3-modified Bodipy derivatives in the field of colorimetric and fluorescent probes.

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