A new selective fluorescent sensor for Zn(II) ions based on poly(azomethine-urethane) Ali Avcı a,b , _ Ismet Kaya b,⇑ a Celal Bayar University, Faculty of Sciences and Arts, Department of Chemistry, 45140 Manisa, Turkey b Çanakkale Onsekiz Mart University, Faculty of Sciences and Arts, Department of Chemistry, Polymer Synthesis and Analysis Lab., 17020 Çanakkale, Turkey article info Article history: Received 4 August 2014 Revised 24 January 2015 Accepted 18 February 2015 Available online xxxx Keywords: Poly(azomethine-urethane) Zn(II) sensor Fluorescence sensor Optical sensor abstract A new and selective fluorescent sensor based on poly(azomethine-urethane) (PAMU) is synthesized and characterized by FT-IR, 1 H NMR, and size exclusion chromatography (SEC) techniques. The new sensor shows a high selectivity for Zn(II) over other metal cations in DMF/deionized H 2 O (1:2, v/v). The fluores- cence sensor gives a linearly and highly stable response to Zn(II) as an increasing emission peak at 595 nm. The sensitivity limit of the new sensor is found to be 11.4  10 3 mol L 1 . The results show that the proposed sensor can be efficiently used as a simple method for the detection of Zn(II) ions. Ó 2015 Elsevier Ltd. All rights reserved. The design and synthesis of new chemosensors for the efficient detection of heavy or transition metal ions are important research topics in analytical, biomedical, and environmental sciences. 1 These metal ions affect biological systems in many different ways ranging from being essential trace elements to acting as acute tox- ins. 2,3 Among those ions, the zinc ion (Zn 2+ ) is the second most abundant transition metal ion in the human body next to iron. It is indispensable for mediating many enzyme-catalyzed reactions, and therefore plays crucial roles in many important biological pro- cesses. 4,5 Many enzymatic, cellular, and neurological functions are under the direct control of Zn 2+ ions. 6,7 The zinc ion is also known to have a role in neurological disorders such as Alzheimer’s disease, Parkinson’s disease, and epileptic seizures. 8,9 There are several methods used for the determination of heavy metals such as atomic absorption spectrometry (AAS), 10,11 fast neutron activation analysis, 12 inductively coupled plasma atomic emission spectrometry, 13 and electrochemical methods. 14–16 How- ever, these methods are relatively costly to employ and difficult to apply. As an alternative to these expensive methods, many optical sensors have been developed. 17,18 Optical sensors have a number of advantages including low cost, high sensitivity, freedom from electrical interference, safety, and are easy to apply. 19 In addition, many analytes which cannot be detected by other methods can be analyzed by optical sensors. Fluorescence signaling is highly sensitive and can be used directly for chemosensors with fiber optic systems. 20,21 Also, a significant advantage of this sensing method is the ease of handling. The development of a new gen- eration of fluorescent agents containing chelating groups should enable the detection of heavy metals more efficiently. Polymers have also been used in this field to obtain more selective and sen- sitive sensors. 22,23 Taking into consideration all the above factors, we describe an easy recognition and detection of Zn(II) in aqueous solutions via the fluorescence measurements employing a polyphenol derivative of poly(azomethine-urethane) (P-TP-4AP). The polymeric sensor was prepared according to the literature 24,25 and was found to be a good candidate for optical detection of Zn(II). An important advantage of the proposed Zn(II) sensor is its ease of production and its fine-sensing and stable properties. The polyphenol derivative, poly(azomethine-urethane) (P-TP- 4AP), was synthesized in three steps. 26 The first step consisted of the copolymerization reaction of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with 2,4-toluenediisocyanate (TDI) to form a novel polyurethane (PU). The second step involved the graft copolymer- ization reaction of 4-aminophenol (4-AP) with the polyurethane to form a poly(azomethine-urethane) (PAMU) (TP-4AP). 27 In the third step, the synthesized PAMU was converted into its polyphenol derivative (P-TP-4AP) through oxidative polycondensation in an aqueous alkaline medium using sodium hypochlorite (30%) as the oxidant, as reported in the literature. 28 The yield of P-TP-4AP was found to be 70%. 29 All the synthetic procedures are summa- rized in Scheme 1. http://dx.doi.org/10.1016/j.tetlet.2015.02.079 0040-4039/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +90 286 218 00 18; fax: +90 286 218 05 33. E-mail address: kayaismet@hotmail.com ( _ I. Kaya). Tetrahedron Letters xxx (2015) xxx–xxx Contents lists available at ScienceDirect Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet Please cite this article in press as: Avcı, A.; Kaya, _ I.Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.02.079