A newly synthesized thiazole derivative as a fluoride ion chemosensor: Naked-eye, spectroscopic, electrochemical and NMR studies Ahmet Burak Sarıgüney, Ahmet Özgür Saf, Ahmet Cos ßkun ⇑ Chemistry Department, Necmettin Erbakan University, 42099 Meram, Konya, Turkey highlights New thiazole derivative have been synthesized and characterized. Complexation behaviors for various anionic species investigated. It is a very good naked eye detection sensor for the fluoride anion. graphical abstract article info Article history: Received 30 November 2013 Received in revised form 4 February 2014 Accepted 7 February 2014 Available online 22 February 2014 Keywords: Fluoride Isatin-thiazole ring Anion sensor Voltammetric method 1 H NMR titration abstract 2,3-Indoledione 3-thiosemicarbazone (TSCI) and a novel compound 3-(2-(4-(4-phenoxyphenyl)thiazol-2- yl)hydrazono)indolin-2-one (FTHI) were synthesized with high yield and characterized by spectroscopic techniques. The complexation behaviors of TSCI and FTHI for various anionic species (F , Cl , Br ,I , NO 2 , NO 3 , BzO , HSO 4 , ClO 4 ) in CH 3 CN were investigated and compared by UV–vis spectroscopy, cyclic vol- tammetry and 1 H NMR titration techniques. FTHI showed high degree of selectivity for fluoride over other anions. This selectivity could be easily observed by the naked eye, indicating that FTHI is potential color- imetric sensor for fluoride anion. Ó 2014 Elsevier B.V. All rights reserved. Introduction Selective recognition and sensing of anions using neutral mole- cules as receptors has been one of the most important areas in chemistry due to the importance of anions in biological, chemical, industrial and environmental processes [1–3]. Considering the par- ticular importance of anions, it has been important to fabricate new anion sensors or develop new techniques for sensing anions. A number of anion sensors containing different moieties have been developed [4] for fluoride [5], benzoate [6], hydrogen sulfate (bisul- fate) [7] and pyrophosphate anions [8]. In particular, the fluoride anion is one of the most interest received special attention as it plays crucial roles in the dental care and treatment of osteoporosis. However, excess fluoride anion causes several serious diseases such as bone disorder (fluorosis), collagen breakdown, depression of thy- roid activity and disruption of immune systems [9,10]. The anion binding mainly occurs through weak hydrogen bond- ing or electrostatic interactions and thus is usually weaker than cat- ion binding [11]. In general, the receptors must provide one or more hydrogen-bonding donor groups such as ANH or AOH. Correct ori- entation of the hydrogen bond donors and/or acceptors can also provide selective anion recognition and color changes [12–14]. It should be noted that anions have a wide variety of geometries and comparatively large sizes, and this have to be taken into ac- count in the development of selective anion sensors. http://dx.doi.org/10.1016/j.saa.2014.02.032 1386-1425/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +90 505 659 5313; fax: +90 332 323 8225. E-mail address: acoskun42@gmail.com (A. Cos ßkun). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 128 (2014) 575–582 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa