Detection of Al³⁺ and Hg²⁺ ions with anthracene appended Schiff base and its reduced analogue

Abstract

Chemosensor 1 has been synthesized via a one-pot synthetic route incorporating anthracene and azomethine (HCN) units acting as signaling and binding units, respectively. Chemosensor 1 offered selective colorimetric and fluorometric response towards Al³⁺ and Hg²⁺ ions among other cations in CH₃OH. Solution of 1 in methanol exhibited a naked eye color transition from yellow to colorless on addition of Al³⁺ and Hg²⁺ ions. In case of emission experiments, non-fluorescent solution of 1 showed major enhancement in intensity giving blue fluorescence for both metal ions. The limits of detection were calculated to be 1.04 and 0.8 µM for Al³⁺ and Hg²⁺, respectively, using fluorescence titrations. Further, reduced form of Schiff base 1 (2) has also been synthesized in order to compare the importance of azomethine (HCN) and (H₂CNH) moieties in selective coordination. However, the reduced analogue 2 did not exhibit selective detection towards any of the ions.

Graphical Abstract

Keywords:

• Schiff base
• anthracene
• chemosensor
• naked eye
• DFT

Acknowledgment

The authors are greatly thankful to SAIF, Panjab University Chandigarh for recording the NMR and mass spectra.

Disclsoure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are grateful to UGC (Grant No. 23/12/2012 (ii) EU-V) and DST PURSE-II (Grant No. 48/RPC) for the fellowship.