Selective “turn-on” probes for CN− based on a fluorophore skeleton of 1,3-dihydroisobenzofuran

• Two novel “turn-on” probes with high selectivity have been synthesized.
• Probe A-Cu2+ is specific and sensitive for CN− through a displacement mechanism.
• Probe B is selective and sensitive for CN− upon the addition reaction.

Two novel fluorescence “turn-on” cyanide probes based on the 1,3-dihydroisobenzofuran skeleton have been designed and synthesized: a terpyridyl-Cu2+ ensemble sensed CN− in THF-H2O (1:1, v/v), and a dicyanovinyl-containing compound sensed CN− in CH2Cl2 and THF. Titration of CN− with terpyridine-Cu2+ complex caused a displacement reaction that turned on the fluorescence of A-Cu2+ at 605 nm. The detection limit of A-Cu2+ for CN− was calculated to be 3.15 × 10−6 M. In the presence of CN−, the dicyanovinyl-bearing probe underwent a nucleophilic addition, showing 85-fold enhancement of fluorescence, with a detection limit of 5.39 × 10−8 M. Our results demonstrate that these two strategies for designing a fluorophore skeleton based on the 1,3-dihydroisobenzofuran lead to highly selective “turn-on” probes for CN−.

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