Rhodamine-Appended Bipyridine: XOR and OR Logic Operations Integrated in an Example of Controlled Metal Migration

A new bipyridyl derivative 1 bearing rhodamineB as visible fluorophore was designed, synthesized and characterized as a fluorescent and colorimetric sensor for metal ions. Interaction with Cu2+, Zn2+, Cd2+, Hg+, and Hg2+ ions was followed by UV/Vis and emission spectroscopy. Upon addition of these metal ions, different colorimetric and fluorescent responses were observed. Off-on-off (Cu2+, Zn2+, and Hg2+) and off-on (Hg+ and Cd2+) systems were obtained. Probe 1 was explored to mimic XOR and OR logic operations for the simultaneous detection of Hg+-Cu2+ and Hg+-Zn2+ pairs, respectively. DFT calculations were also performed to gain insight into the lowest-energy gas-phase conformation of free receptor 1 as well as the atomistic details of the coordination modes of the various metal ions.