Optical spectroscopy studies of the complexation of chromogenic azo-calix [4]arene with Eu 3+ , Ag + and Cu 2+ ions A. Rouis a,b, ⁎ , R. Mlika a , C. Dridi a , J. Davenas b , H. Ben Ouada a , H. Halouani c , I. Bonnamour c , N. Jaffrezic d a Laboratoire de Physique et Chimie des Interfaces, Faculté des Sciences de Monastir, Avenue de l'environnement, 5000 Monastir, Tunisia b Ingénierie des Matériaux Polymères: LMPB,43 boulevard du 11 Novembre 1918, Université Claude Bernard—Lyon 1, 69622 Villeurbanne, France c Laboratoire Appliqué à la Chimie de l'environnement: LACE 43 Boulevard du 11 Novembre 1918, Université Claude Bernard—Lyon 1, 69622 Villeurbanne, France d CEGELY, Ecole Centrale de Lyon, 36 rue Guy de Collongue, 69131 Ecully, France Available online 15 December 2005 Abstract Due to their potential applicability as selective receptors in electrochemical and/or optical sensors (optodes) a new family of chromogenic calix [4]arenes derivatives were investigated. The complexing properties of these molecules towards metallic cations and lanthanides and the photophysical properties of the formed compounds in acetonitrile solution have been studied by UV/Vis spectroscopy. The molar ratio method revealed that the stoichiometry of calix[4]arenes 1a and 1b to Eu(III) in the complex is 1 : 1. The stability constants of the complexes have been determined. © 2005 Elsevier B.V. All rights reserved. Keywords: Chromophore; Calix[4]arene; Complexation; Spectrophotometry 1. Introduction Optical transduction based sensors have been extensively investigated since the late 1980s. The optical transduction technique is an attractive alternative to electrochemical meth- ods. The requirement at the base of optical sensors is that an optically responsive mechanism is coupled to the ion–ligand complexation process, e.g. immobilizing a dye (chromoiono- phore) in the membrane with the ligand. An advantage is that there is no modification made to the ligand. Calixarenes are the third generation of supramolecular receptors after cyclodex- trines and crown ethers [1]. It is possible to prepare various calixarene derivatives by functionally modifying either the upper and/or lower rims. The modification of calixarenes has been the subject of numerous studies, due to their potential applicability as active ligands in electrochemical and/or optical sensors (optodes) [2–5] with different selectivities for various guest ions and small molecules. Alternatively, dyes can be attached directly to the calixarene [6,7]. Various types of chromogenic calix[4]arene derivatives have recently been synthesised, which have shown selective complexation with metal ions [8,9]. The potential application of new calix[4]arene derivatives in optical sensors has been studied [10,11]. McKer- vey and Diamond [12,13] demonstrated that novel chromo- genic calixarene-based ligands could be used for the optical recognition of alkali ions. Bodenant et al. [14] reported a bipyryl calix[4]arene-based receptor designed for the optical detection of Cu(II) and Ni(II) metal ions in solution. Bitter et al. [15] studied the complex forming behavior and selectivity of a calix[4]arene derivative with alkali and alkali earth ions. New chromogenic calix[4]arene derivatives have been syn- thesised [16] by functionalization of the lower rim of the chro- mophore with donor or acceptor groups involving azote and/or oxygen atoms. These new supramolecules have shown selectiv- ity for many types of metals and applicability in complexation for others. Affinity of the di- and tri-β-cétoimine calix[4]arenes has been investigated with Cu(II), Hg(II) and Ag(I). Addition- ally, the azo-calix[4]arenes derivatives compounds have devel- oped extraction properties towards many metals [16]. Materials Science and Engineering C 26 (2006) 247 – 252 www.elsevier.com/locate/msec ⁎ Corresponding author. Laboratoire de Physique et Chimie des Interfaces, Faculté des Sciences de Monastir, Avenue de l'environnement, 5000 Monastir, Tunisia. Tel.: +216 73 500 274; fax: +216 73 500 287. E-mail address: rouisahlem2@yahoo.fr (A. Rouis). 0928-4931/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.msec.2005.10.081