Turn-on fluorescent naphthalimide-benzothiazole probe for cyanide detection and its two-mode aggregation-induced emission behavior

T Sheshashena Reddy; Hyungkyu Moon; Myung-Seok Choi

doi:10.1016/j.saa.2021.119535

Turn-on fluorescent naphthalimide-benzothiazole probe for cyanide detection and its two-mode aggregation-induced emission behavior

Spectrochim Acta A Mol Biomol Spectrosc. 2021 May 5:252:119535. doi: 10.1016/j.saa.2021.119535. Epub 2021 Feb 3.

Authors

T Sheshashena Reddy¹, Hyungkyu Moon¹, Myung-Seok Choi²

Affiliations

¹ Division of Chemical Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, South Korea.
² Division of Chemical Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, South Korea. Electronic address: mchoi@konkuk.ac.kr.

PMID: 33582439
DOI: 10.1016/j.saa.2021.119535

Abstract

Naphthalimide-benzothiazole conjugate (NBTZ) linked by cinnamonitrile was designed, synthesized, and fully characterized by NMR (¹H, ¹³C, DEPT, HSQC) and high-resolution mass spectrometry. NBTZ exhibited unique turn-on fluorescence in the presence of CN^- with relatively high selectivity compared to other anions such as SCN^-, HSO₄^-, ClO₄^-, NO₃^-, Cl^-, Br^-, I^-, and PO₄^-3 in tetrahydrofuran (THF). The detection limit for CN^- was found to be 3.35 × 10^-8 M in THF. The sensing mechanism was analyzed through ¹H, ¹³C, DEPT, and mass spectroscopy. NBTZ also showed two-mode aggregation-induced emission (AIE) in THF-H₂O mixtures. In a 30:70 THF-H₂O (v/v) mixture, the maximum AIE was observed at 430 nm (blue) because of the rotation of the CC bond between the naphthalimide ring and the phenyl ring was restricted. In 10:90 THF-H₂O (v/v), a new red-shifted AIE appeared at 490 nm (cyan), due to the extended π-conjugation induced by restriction of rotation of the CC bond between the benzothiazole and naphthalimide rings.

Keywords: Aggregation-induced emission; Crystal structure; Cyanide detection; Fluorescent probe; Turn-on fluorescence.