A novel fluorene-derivative Schiff-base fluorescent sensor for copper(II) in organic media

- Fluorescent chemosensor formed highly stable binuclear complexes with Cu(II).
- Sensor showed distinctive selectivity, elevated binding constant and one of the lowest detection limit to Cu(II).
- Stern-Volmer, Benesi-Hilderbrand and Job's methods suggest a 2:1 (metal/ligand) stoichiometry.

A new Schiff-base sensor containing fluorene was synthesized and investigated for determination of metal ions in dimethylsulfoxide solutions. Fluorescence was quenched upon coordination, showing selectivity for Cu(II) over Mn(II), Fe(III), Ni(II), Pd(II), Zn(II), Ca(II), Hg(II), Na(I) and K(I) in a concentration range of 1.00 to 10.0 × 10‐7 mol L‐1. Good results were observed for sensor 1 derived from 2‐formylpiridine. Benesi‐Hilderbrand formalism indicates that the most abundant species formed have 2:1 (metal/ligand) ratio with a calculated biding constant of 1.74 × 1012 L2 mol−2 in good agreement with the Stern‐Volmer constant KSV at 2.26 × 1012 L2 mol−2. The limit of detection (LOD) for Cu(II) was found to be 0.037 μmol L−1 with a relative standard deviation (RSD) of 3.19% in the copper(II) concentration range of 3.00 to 7.00 × 10−7 mol L‐1.