A Multifunctional Fluorescent Probe Based on 1,8-Naphthalimide for the Detection of Co2+, F−, and CN−

Cations and anions are indispensable resources for the development of nature and modern industry and agriculture, and exploring more efficient technology to monitor them is urgently needed. A multifunctional fluorescent probe based on 1,8-naphthalimide, N-(2-thiophenhydrazide)acetyl-4-morpholine-1,8-naphthalimide (TMN), was successfully designed and synthesized for the detection of Co2+, F−, and CN−, with N-carboxymethyl-4-morpholine-1,8-naphthalimide and thiophene-2-carbohydrazide as starting materials. TMN displayed superior stability in MeCN with an “on–off” mode towards Co2+, F−, and CN− by the naked eye. The linear response ranges of TMN were 0–3 and 4–19 μM with a detection limit of 0.21 μM for detecting Co2+, 0–5 and 5–22 μM with a detection limit of 0.36 μM for F−, and 0–10 and 10–25 μM with a detection limit of 0.49 μM for CN−. TMN could also recognize Co2+, F−, and CN− in real samples. Finally, the possible sensing mechanisms of TMN for detecting Co2+, F−, and CN− were deeply investigated. These results implied that TMN could be a potential chemosensor for monitoring metal cations and anions sensitively and selectively and could be used in real sample detection.