Coloration Technology. 2019;00:1–9. wileyonlinelibrary.com/journal/cote | 1 © 2019 The Authors. Coloration Technology © 2019 Society of Dyers and Colourists 1 | INTRODUCTION In recent decades, because of their tremendous application in sensing ions and mercapto biomolecules, fluorescent sensors have been the subject of considerable interest. 1-4 Recognition of anions to enable their analytical detection is important because of the crucial role they play in living systems and in the environment. 5,6 Of the various important anions, cya- nides are among the most toxic, but they are still widely used in the mining, galvanic and chemical industries. 7 Cyanides are well adsorbed via the gastrointestinal tract or skin, and also by the respiratory track. Exposure to sodium cyanide at a concentration of 286 mg/m 3 or to hydrogen cyanide at a concentration higher than 300 mg/m 3 for 1 minute may be fatal. Many different methods have been developed for the detection of cyanide anions, including electrochemistry, cap- illary electrophoresis, fluorometry and chromatography. 8-11 Unfortunately, most of these methods require sophisticated instruments and involve complicated procedures. Therefore, the detection and analysis of cyanide anions by using che- mosensors that exhibit optical responses (colorimetric and/ or fluorescence) has attracted increasing attention because of their high sensitivity and simplicity. 12 Currently, fluorescent probes for the detection of cyanide anions take advantage of their characteristic properties such as strong nucleophilicity and high affinity towards copper ions. Cyanide sensors are based on hydrogen bonding, 13,14 nucleophilic addition to the carbonyl moiety, 15-17 and formation of cyanide anion com- plexes. 18-20 Among these reactions, the nucleophilic addition was found to have a high selectivity and sensitivity for the recognition of cyanide anions. Most fluorescent probes are designed to exhibit fluorescence quenching (on–off) and fluorescence enhancement (off–on) as the detection signal. These fluorescent probes act via fundamental photophysical mechanisms including intramolecular charge transfer, pho- toinduced electron transfer and fluorescence resonance en- ergy transfer, among others. 21-24 In our previous paper, the synthesis, spectroscopic char- acterisation and potential application of dyes derived from 2(1H)‐quinolone with dicyanoethylene, 25,26 maleimide 27 and aldehyde 28 moiety as sensors for the biologically important thiols was reported. In this study, we present the dyes 1‐5 based on the 2(1H)‐ quinolone skeleton containing dicyanoethylene groups acting as efficient chemosensors for the detection of cyanide anions. The structures of the studied dyes are presented in Scheme 1. Received: 8 May 2019 | Revised: 13 August 2019 | Accepted: 16 September 2019 DOI: 10.1111/cote.12438 ORIGINAL ARTICLE Dyes based on the 2(1H)‐quinolone skeleton as potential colorimetric and fluorescent sensors for cyanide anions Jolanta Kolińska | Aleksandra Grzelakowska | Jolanta Sokołowska Faculty of Chemistry, Institute of Polymer and Dye Technology, Lodz University of Technology, Lodz, Poland Correspondence Jolanta Kolińska, Institute of Polymer and Dye Technology, Faculty of Chemistry, Lodz University of Technology, Stefanowskiego 12/16, 90‐924 Lodz, Poland. Email: jolanta.kolinska@p.lodz.pl Abstract The sensing properties of dyes based on 2(1H) quinolones containing dicyanoethyl- ene groups towards selected anions such as CN − , F − , I − , Cl − , SCN − , CH 3 COO − , NO - 2 and ClO - 4 were evaluated. The spectroscopic responses of these compounds were investigated in a solution of acetonitrile/water (1:9, v/v) and phosphate buffer at a pH of 7.4. These dyes were found to act as efficient colorimetric and high turn–off fluorescent sensors to cyanide anions. The fluorescence intensity was linearly related to the concentration of CN − from 1 to 10 µmol/L, and the detection limits reached a micromolar level of 6.7, 11.1, 3.8 and 7.2 µmol/L for 1‐4, respectively. The cytotoxic effect of the dyes against human neuroblastoma cells (SH‐SY5Y) was also deter- mined by MTT assay. The examined compounds exhibited slight cytotoxicity against cells under experimental conditions.