Detection of the +3 Oxidation State of Metal Ions with the Aid of a Rhodamine‐Based Dye and Applications in Construction of Complex Logic Circuits and Living Cell Imaging

Detection of correct oxidation state of a metal ion is important to understand its speciation and redox properties. Some of rhodamine derivatives can identify Al 3+ , Cr 3+ and Fe 3+ as the trivalent cations. We have synthesized a rhodamine derivative, HL‐qui, from the reaction of N‐(rhodamine‐6G)lactam‐ethylenediamine with quinoline‐2‐carboxaldehyde for the colorimetric as well as fluorogenic detection of all of metal ions with +3 oxidation state such as Al 3+ , Cr 3+ , Fe 3+ , Ga 3+ , In 3+ , Tl 3+ and Gd 3+ . In the presence of these trivalent cations, colorless and nonfluorescent HL‐qui turns pink and strongly fluorescent in HEPES buffer (10 mM) in H 2 O/ethanol=1/9 (v/v) (pH 7.4) as its spirolactam ring gets open to show the changes in color and fluorescence properties. High sensitivity of the probe towards the cations is reflected from the limit of detection values that are in n M range. To the best of our knowledge, there is no such report where fluorescence sensing has been utilized to determine oxidation state. This multi‐ion sensing feature has been used for fabrication of multi input‐output based logic circuit using Boolean algebraic method. It has been used in imaging of metal ions in living cell (L6 cells).