Month 2019 Naked Eye Detection of Carbonate, Hydroxide, and Cyanide Ions with 1,4′-Diazaflavonium Bromides: A Simple Spectrophotometric Method for Cyanide Determination Nuran Kahriman, a Serhat Gün, a Abidin Gümrükçüoğlu, a Nurettin Yaylı, b Ümmühan Ocak, a * and Miraç Ocak a a Department of Chemistry, Faculty of Science, Karadeniz Technical University, Trabzon, Turkey b Faculty of Pharmacy, Karadeniz Technical University, Trabzon, Turkey *E-mail: uocak@ktu.edu.tr Received August 8, 2018 DOI 10.1002/jhet.3669 Published online 00 Month 2019 in Wiley Online Library (wileyonlinelibrary.com). Anion sensor properties of N-alkyl-substituted 1,4′-diazaflavonium bromides in methanol–water were evaluated by UV–vis spectrometry. Pronounced changes were observed in the absorption spectra of all com- pounds for only OH À , CO 3 2À , and CN À among F À , Cl À , Br À ,I À , OH À , CO 3 2À , NO 3 À , PO 4 3À , CN À , SO 4 2À , HSO 4 À , HCO 3 À , SCN À , NO 2 À , and P 2 O 7 2À ions. Two new absorption bands at 385 and 685 nm accompanying the distinct color change for OH À , CO 3 2À , and CN À ions were observed in case of all compounds. The color changes were from pink to blue for CO 3 2À and OH À ions and from pink to purple for CN À ion. Thanks to the distinct color change, the compounds can be used as selective colorimetric anion sensors. Linear changes of absorbance of N-heptyl-substituted compound at 385 nm as a function of the ion concentration were used to determine CN À ion in water samples. Detection and quantification limits of the proposed method were 0.94 and 2.82 mg/L, respectively. J. Heterocyclic Chem., 00, 00 (2019). INTRODUCTION Flavones compose a class of naturally occurring substances widely distributed in plants and have pharmacological activities [1–7]. Azaflavones and diazaflavones are analogues of flavones with an annular nitrogen atom in the phenyl ring [8,9]. Over the last 30 years, N-alkylpyridinum salts of many compounds that comprise the azaflavone have been synthesized by several researchers and shown to have antibacterial, antimicrobial, antituberculostatic, and anti-inflammatory activities [10–12]. N-Alkylpyridinium salts also have many other usage such as being phase transfer catalysts, acylating agents, potential solvents in synthesis, biocides, dyes, and cationic surfactants. Moreover, they have key role for the production of pharmacologically important piperidine, dihydropyridine, and tetrahydropyridine skeletons. The classical methods for synthesizing N- alkylpyridinium salts were given in the literature [10–13]. Recently, a 1,4-diazaflavone compound was synthesized by a simple solid-phase microwave-assisted method with the cyclization of 2-amino (E)-4-aza-chalcone [10]. From the 1,4-diazaflavone compound or directly from 2-amino (E)-4-aza-chalcone, a series of N-alkyl-substituted 1,4- diazaflavanonium bromides dyes (Scheme 1) were prepared with the corresponding alkyl halides [10]. These compounds showed good antimicrobial activity for the Gram-positive bacteria. The better activity was obtained with the optimum length of the alkyl chain with 6–10 carbon atoms among the compounds [10]. Recently, we focused to investigate fluorescence properties of some synthetic flavonoid compounds to use them as analytical reagents [14,15]. It has been envisaged that these compounds may be green reagents due to their similar structures to natural flavonoid compounds. Therefore, a chalcone compound [15] and an azaflavanon-3-ol compound [14] as fluorescent reagents were used in iron determination in real samples. As a continuation of those studies, the present study focuses on revealing ion sensor properties of the 1,4- diazaflavonium bromides. These compounds also have © 2019 Wiley Periodicals, Inc.