Solvent-dependent selective naked eye chromofluorogenic multifunctional rhodamine-based probe for Al3+, Cu2+, Hg2+, S2- and CN- ions

The solvent-dependent selective naked eye chromofluorogenic multifunctional rhodamine-based probe 3 for Al3+, Cu2+, Hg2+, S2- and CN- ions was synthesized and its spectral, luminescent and ion-ochromic properties were studied. The compound obtained exists in the spirolactam form, confirmed by data of H-1, COSY, HSQC, HMBC and C-13 NMR spectroscopy. In ethanol, Al3+ ions selectively, even in the presence of other metal cations (Na+, Ba2+, Zn2+, Cd2+, Ni2+, Co2+, Cu2+, Hg2+ and Fe3+) initiate the opening of the spirolactam ring, accompanied by the appearance of a new absorption band at 556 nm and the naked eye effect with a change in the yellow-green color of the solution to orange-pink. At the same time, the initial fluorescence 3 at 539 nm shifts to the longer 579 nm spectral region. The use of acetone as a solvent allows the selective detection of copper(II) cations that turn the yellow color of a solution of 3 to pink-purple (lambda(abs) 563 nm) due to the formation of the ring-open complex 3.Cu2+ that exhibits emission at 580 nm. Selective detection of Hg2+ in acetonitrile results in the naked eye effect characterized by a change in the color of the solution from bright yellow to pink-cherry (lambda(abs) 564 nm). The fluorescence of the mercury(II) complex is observed at 587 nm. Complexes 3.Cu2+ and 3.Hg2+ were used for the sequential selective recognition of S2- and CN- anions, respectively. A combinatorial molecular logic gate was designed based on the cation/anion sensing ability of probe 3. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

A solvent-dependent selective naked-eye chromofluorogenic multifunctional rhodamine-based probe 3 was synthesized for the detection of Al3+, Cu2+, Hg2+, S2-, and CN- ions. The probe exhibited different spectral, luminescent, and ion-ochromic properties in different solvents.