Selective sensing of silver ion using berberine, a naturally occurring plant alkaloid

• Berberine (Bn) an alkaloid of pharmacological interest is used as a sensing probe.
• Bn selectively senses Ag+ ion [1 × 10−5 M] over other metal ions in EtOH-H2O medium.
• Visible colour change from yellow to orange is noticed.
• Upon binding to Ag+ ion quenching of intramolecular charge transfer occurs.
• Mechanism is supported by TD-DFT calculations, ESI-MS and Job's plot.

Berberine (Bn), an important traditional medicinal herb with anticancer, antitumour and antidiabetic activities, is effectively utilized as a sensing probe for silver ion with good sensitivity and selectivity, using absorbance and fluorescence studies. The effect of presence of other metal ions with Bn is also investigated and Bn is found to be selective towards Ag+ ion over other metal ions such as Cu2+, Zn2+, Sn2+, Ni2+, Ba2+, Bi2+, Pb2+, Co3+, In3+, Mn2+, Fe2+, Fe3+, Li+, Hg2+ and Ca2+ with a detection limit of 0.1 × 10−4 mol L−1. The colour changes from yellow to orange when Ag+ ion is added and other metal ions failed to show any visible colour change. The effective quenching of Bn upon binding with Ag+ ion is attributed to suppression of intramolecular charge transfer (ICT).

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