Synthesis, sensor activity and logic behaviour of a novel bichromophoric system based on rhodamine 6G and 1,8-naphthalimide

• Bichromophoric system with Rhodamine 6G and a 1,8-naphthalimide unit is synthesized.
• Donating 1,8-naphthalimide is designed as a PET based fluorescence probe.
• System manifests excellent signalling response to protons, Cu2+ and Hg2+ ions.
• Logic functions OR and INHIBIT are achieved.
• Two output combinatorial logic circuit with three chemical inputs is demonstrated.

A novel fluorescence sensing system based on rhodamine 6G and 1,8-naphthalimide fluorophores was synthesized and investigated. The system was designed as a wavelength-shifting bichromophoric molecule where the 1,8-naphthalimide moiety is an energy “donor” capable of absorbing light and efficiently transferring the energy to a focal Rhodamine 6G “acceptor”. Furthermore, the 1,8-naphthalimide unit was configured on the “fluorophore-spacer-receptor” format. Thus, the distinguishing features of fluorescence resonance energy transfer systems were successfully combined with the properties of photoinduced electron transfer and classical ring-opening sensor systems. The synthesized compound shows excellent signalling properties towards protons as well as Cu2+ and Hg2+ over the representative metal ions. Due to the remarkable fluorescence changes in the presence of protons, Cu2+ and Hg2+ ions the novel system is able to act as a two output combinatorial logic circuit with three chemical inputs.

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