untitled European Journal of Chemistry 5 (2) (2014) 339‐342 European Journal of Chemistry ISSN 2153‐2249 (Print) / ISSN 2153‐2257 (Online)  2014 Eurjchem Publishing ‐ Printed in the USA http://dx.doi.org/10.5155/eurjchem.5.2.339‐342.1003 European Journal of Chemistry Journal homepage: www.eurjchem.com Cation binding by some pyranopyridothiazole derivatives Olfa Naouali a, Hussain Soleiman b,c and Lassaad Baklouti a,b,* a Laboratory of Applied Chemistry and Natural Substances Resources and Environment, Faculty of Sciences at Bizerte, Carthage University, Zarzouna‐Bizerta, 7021, Tunisia b Chemistry Department, Sciences and Arts College, Al‐Qassim University, Al‐Rass, 53200, Kingdom Saudi Arabia c Chemistry Department, Aswan Faculty of Sciences, Aswan University, Aswan 3567, Egypt *Corresponding author at: Chemistry Department, Sciences and Arts College, Al‐Qassim University, Al‐Rass, 53200, Kingdom Saudi Arabia. Tel.: +966.05.32056252. Fax: +966.016.3512515. E‐mail address: bakloutilassaad@yahoo.fr (L. Baklouti). ARTICLE INFORMATION ABSTRACT DOI: 10.5155/eurjchem.5.2.339‐342.1003 Received: 15 December 2013 Received in revised form: 23 February 2014 Accepted: 25 February 2014 Online: 30 June 2014 KEYWORDS The binding properties of a cyanopyranopyridothiazole (L1), aminothiazole (L2), iminothiazole (L3) and phenyliminothiazole (L4) derivatives toward some transition metal and heavy metal cations, have been investigated in methanol, followed by UV spectrophotometry absorption and conductivity determination. The stoichiometries of the formed complexes and their stability constants were determined by a digital data processing. The study of extraction properties from water into dichloromethane shows a lower extraction affinity for the metal picrates with L1, unlike L2‐L4 which are better extracted and specially Fe(III) with L4. Thiazole Extraction Stoichiometry Complexation Stability constants Inclusion properties 1. Introduction The pyranopyridothiazole derivatives are biologically interesting molecules which have established utility in the pharmaceutical compounds. These ring systems have a wide application range in the biological activities and the pharma‐ cological actions [1‐5], such as antibacterial [6,7] and inhibitory activities [8‐10]. Otherwise, the pyranopyrido thiazole deriva‐ tives found a wide uses in the industry compounds and the chemistry of dyes and pigments such as laser technologies [11,12], colour and non‐colour photographic processes [13], optical disk as recording media [14] and inks [15]. Recently, a different heterocyclic cyanine dyes have been reported as high sensitivity and low fogging information recording media of high reflectivity and carrier‐to‐noise ratio, laser disc media, laser‐ sensitive optical recording material. Besides their use as colorants [16], they have considerable potential for application in energy conversion [17]. Moreover, the structure activity studies revealed that the synthesized compounds are also important in many other fields. Referring to our previous work [18], attempts have been made in order to synthesize a new fused and isolated heterocyclic compounds, as well as some compounds of cyanine dyes like apocyanine and monomethine cyanine dyes [19]. 2. Experimental 2.1. Instruments and materials The UV spectra have been recorded on a Perkin Elmer Lambda 11 spectrophotometer. Methanol (Riedel‐deHaën for HPLC), acetonitrile (SDS for HPLC, 0.03% water content) and dichloromethane (Fluka, purum) are commercial and used without further purification. The supporting electrolyte used in the determination of the stability constant is NEt4Cl and NEt4ClO4 (Acros Organics). The chosen metal salts have been chlorides or perchlorates (Fluka, purum). The picrate salts employed in the extraction have been prepared as described in the literature [20,21]. 2.2. Synthesis of thiazole derivatives (L1, L2, L3 and L4) The synthesis of thiazole derivatives L1, L2, L3 and L4 have been achieved via interaction of 4,5‐dihydro‐2‐ehylacetate‐4‐ oxothiazole L1 with benzilidenemalononitrile L2, amido acrylonitrile L3 and amido cinnamonitrile L4 according to Al‐ Ayed et al. [19] (Figure 1). 340 Naouali et al. / European Journal of Chemistry 5 (2) (2014) 339‐342 Table 1. Stability constants log βxy of the complexes of L1, L2, L3 and L4 with some transition metal cations in methanol at 25 °C, I = 10‐2 M, (0.01 ≤ n‐1 ≤ 0.14). Ligands M:L Co(II) Ni(II) Cu(II) Zn(II) Cr(II) Mn(II) Fe(III) Pb(II) Sn(II) L1 1:1 ‐ * 3.42 3.03 3.09 4.10 4.40 4.07 4.01 3.04 L2 1:1 4.10 3.30 3.19 ‐ ‐ ‐ 3.20 ‐ ‐ L3 1:1 2.90 3.12 3.03 3.09 ‐ ‐ 3.16 ‐ ‐ L4 1:1 2.10 3.85 3.19 3.65 ‐ 3.01 3.50 ‐ 4.05 * ‐: Absorbance changes too small to enable satisfactory fitting. L1: Cyanopyranopyridothiazole L2: Aminothiazole L3: Iminothiazole L4: Phenyliminothiazole Figure 1. Chemical structure of ligand. 2.3. Stability constant measurements The stability constants βxy are the concentration ratios [MxLyxn+]/[Mn+]x[L]y following the general equilibrium: yL + xMn+ ⇋ MxLyxn+ (1) where Mn+: metal ion, L: ligand have been determined in acetonitrile and methanol by UV‐absorption spectrophoto‐ metry at 25 °C. The ionic strength has been maintained at 0.01 mol/L using Et4NClO4. The spectra of ligand solutions of concentrations ranging between 1×10‐4 and 2×10‐4 mol/L and increasing the metal ion concentration has been recorded between 220 and 400 nm. Generally the metal to ligand ratio R at the end of the titration did not exceed 20 and the equilibriums were quasi‐ instantaneous for all the systems. Adding the metal salts to the ligand has induced large spectra changes which were enough to allow the analysis of the resulting data using the program “Letagrop” [22]. The best values of the formation constants βxy of the various complex species and their molar absorptivity coefficients for various wavelengths are deduced from the best fit between the experimental and the calculated UV spectra. The best fit is reflected by the lowest value of U (the sum of U values for all given lambda) corresponding to the square sum of the difference between the experimental and the calculated absorbances (U = ∑ (Acal ‐Aexp)2). The βxy values correspond to the arithmetic means of at least three independent experiments. 2.4. Conductimetric studies While the complexation by a neutral ligand is not expected to dramatically alter the molar conductivity of a cationic species, the differences can usually be detected and so the conductance measurement of a ligand solution in to which a metal ion is added can be a useful rapid means of establishing the stoichiometry of a complex ion species. Thus, this procedure was followed to obtain preliminary estimations of the metal ligand ratio in the complexes formed by the heterocyclic amine in methanol solution [23,24]. 2.5. Extraction studies The extraction experiments of alkali metal picrates from water into dichloromethane is performed according to a literature procedure [23]. Equal volumes (5 mL) of neutral aqueous solutions of metal picrate (2.5 ×10‐4 mol/L) and CH2Cl2 solution (5 mL) of ligand (2.5×10‐4 mol/L) have been mixed under magnetic agitation for 24 hours and then left standing for 1 hour in order to obtain a complete separation of the two phases. The concentration of metal picrate remaining in the aqueous phase has been determined from the absorbance A at 355 nm. The percentage extraction (%E) was derived from the following expression in which A0represents the absorbance of the aqueous solution of a blank experiment without ligand: %E =100(A0 ‐ A)/A0 (2) 3. Results and discussion 3.1. Complexation of metal cations in methanol The complexation study of alkali and alkaline earth cations with L1‐L4 shows no affinity toward these cations. However, the mononuclear complexes (1:1) could be shown with the transition metal cations. The logarithms of the stability constants log βxy and the stoichiometries for the different complexes formed by the ligand with some transition metals in methanol are given in Table 1. The transitions metal cations studied in this work show affinities of complexation with the L1, L2, L3 and L4 despite of its total absence with the monovalent and divalent cations (alkaline and alkaline earth cations). This is likely due to the difference in hardness of the considered cations. The selectivity profile of the ligand L1 in the transition metal series shows an affinity in case of iron and chromium complexing in methanol, while this becomes an affinity for cobalt in methanol with the ligand L2. In the other hand, the stability of the complexes formed with L3 are at the same order of magnitude, which shows that this complexation is not affected by the effect of the size in the case of the studied transition metal cations (Figure 2). Naouali et al. / European Journal of Chemistry 5 (2) (2014) 339‐342 341 Figure 2. Stability constants log β11 (determined in methanol) for some transition metal and heavy metal cations with L1‐L4. Similarly ligand L4 for stability of the complexes formed with Ni(II) shows an improved stability in methanol and lower complexation with Cu(II). It is worth to note that the passage from L2 to L4 decreases dramatically the Co(II) complexation (100 times). Moreover, the variation of the selectivity profiles suggests that a non‐dominant cation size in the complexation phenomenon would be also an interesting factor. The basic pattern of the L1 ligand has an affinity for complexing transition metal cations such as chromium and lead and shows the formation of mononuclear complex. The transition to cyanopyranopyridothiazole L2 shows the formation of 1:1 complexes with Ni(II), Cu(II), Co(II), and Fe(III), while it has no affinity for Zn(II), Mn(II), Sn(II), Cr(II) and Pb(II) (Figures 3‐5). Figure 3. UV absorption spectra on complexation of Fe(III) with L2 in methanol (0 ≤ RM/L ≤ 2) at 25 °C. Figure 4. UV absorption spectra on complexation of Zn(II) with L3 in methanol (0 ≤ RM/L ≤ 3) at 25 °C. Figure 5. UV absorption spectra on complexation of Ni(II) with L4 in methanol (0 ≤ RM/L ≤ 5) at 25 °C. By going against the imine function and oxidation of the ligand L3 nitrile function, is accompanied by a decreased affinity of complexing with metal cations include Sn(II) and Mn(II). However, L4 shows affinity for the Sn(II) and theMn(II), this is probably due to the geometry of more flexible ligand in absence of the phenyl groups. It is noteworthy that the oxidation of the nitrile function of the ligand L2 to the amide function of ligand L3 increases the affinity of the Zn(II) cation complexing. On the other hand, the amide appears to decrease the ligandL3 affinity complexation with the Cr(II), Pb(II), Sn(II) and Mn(II) comparing to the ligand L1. Furthermore, the stoichiometries of 1:1 complexes with L1‐L4 were confirmed by the conductimetric studies (Figure 6). Figure 6. Conductometric titration in the case of L4 with Cu(II). Indeed, the stoichiometries determined by the conductometric study of L1‐L4 with the cations Ni(II) and Cu(II) have clearly confirmed those derived from the study by the UV spectrophotometry. 3.2. Extraction of metal picrates A preliminary evaluation of the binding efficiency of pyranopyridothiazole derivatives has been carried out through by solvent extraction of metal picrates into dichloromethane at 20 °C under neutral conditions. The extraction percentages (%E) of some transition metal picrates by L1, L2, L3 and L4 from water into dichloromethane are given in Table 2. In the series of the metal cations studied, the %E obtained with L1 is lower (<10%), but for L2‐L4 the %E varies between 18 and 53%. 342 Naouali et al. / European Journal of Chemistry 5 (2) (2014) 339‐342 Table 2. Extraction percentages (%E) of some transition metal picrates by L1, L2, L3 and L4 from water into dichloromethane, at 25 °C (CL = CM = 2.5 ×10‐4 mol/L). Ligands Co(II) Ni(II) Cu(II) Zn(II) Mn(II) Fe(III) Pb(II) L1 9 6 5 ≤1 ≤1 4 ≤1 L2 23 25 35 22 18 37 29 L3 36 28 32 27 24 46 35 L4 47 34 39 27 30 53 37 However, L4 is a better extractant than L2 and L3 in the series of ligands studied. Looking at the series of cations considered, Fe(III) is a better extract then M(II) cations studied. So, the pyranopyridothiazole derivatives studied do not hexibe meaning selectivity (Figure 7). Figure 7. Trends of the extraction percentages (%E) for some transition metal and heavy metal picrates from water into dichloromethane with L1‐L4. 4. Conclusion The formation of mononuclear species to a ligand L1, L2, L3 and L4 complex with transition metals and heavy metals has been established in this work. The conductimetric titration confirmed mainly the stoichiometries of complexes formed in solution with L1, L2, L3 and L4 determined by the UV spectrophotometric study. However, the extraction study shows a lower extraction affinity for the metal picrates with L1, while L2‐L4 are better extracted and specially Fe(III) with L4. Acknowledgement Special thanks go to Prof. Dr. MalikaTrabelsi Ayadi (LACReSNE‐Bizerte) for her invaluable support. References [1]. Gangjee, A.; Aldair, O.; Queene, S. F. J. Med. Chem. 1999, 42, 2447‐ 2455. [2]. Grivsky, E. M.; Lee, S.; Sigel, C. W.; Duch, D. S.; Nichol, C. A. J. Med. Chem. 1980, 23, 327‐329. [3]. Matulenko, M. A.; Lee C. H.; Jiango, M.; Free, R. R.; Cowart, M. D.; Bayburt, E. K.; Didomenico, S. J.; Gfesser, G. A.; Gomtsyan, A.; Zheng, G. Z.; Mckie, J. A.; Stewart, A. O.; Yu, H.; Kahlhass, K. L.; Alexander, K. M.; McGaraughty, S.; Wismer, C. T.; Mikusa, J.; Marsh, K. C.; Snyder, R. D.; Diehl, M. S.; Kowaluk, E. A.; Jarvisa, M. F.; Bhagwata, S. S. Bioorg. Med. Chem. 2005, 13, 3705‐3720. [4]. Zheng, G. Z.; Lee, C. H.; Patt, J. K.; Perner, R. J.; Jlang, M. O.; Gonitsyan, A. Matulenko, M. A.; Mao, Y.; Koenig, J. R.; Kim, Muchmore, S.; Yu, H.; Kohlhaas, K.; Alexander, K. M.; McGaraughty, S.; Chu, K. L.; Wismer, C. T.; Mikusu, J.; Jarvis, M. F.; Marsh, K.; Kowaiuk, E. A.; Bhagwata, S. S.; Stewarta, A. O. Bioorg. Med. Chem. Lett. 2001, 11, 2071‐2074. [5]. Gfesser, G. A.; Bayburt, E. K.; Cowart, M.; DiDomenico, S.; Gomtsyan, A.; Lee, C. ‐H.; Stewart, A. O.; Jarvis, M. F.; Kowaluk, E. A.; Bhagwat, S. S. Eur. J. Med. Chem. 2003, 38, 245‐252. [6]. Soleiman, H. A.; Khalafallah, A. K.; Abdelzaher, H. M. J. Chin. Chem. Soc. 2000, 47, 1267‐1272. [7]. Soleiman, H. A.;Koraim, A. I. M.;Mahmoud, N. Y. J. Chin. Chem. Soc. 2004, 51, 530‐533. [8]. Gfesser, G .A.; Bayburt, E .K.; Cowart, M.; DiDomenico, S.; Gomtsyan, A.; Lee, C. H.; Stewart, A. O.; Jarvis, M. F.; Kowaluk, E. A.; Bhagwat, S. S. Eur. J. Med. Chem. 2003, 38, 345‐353. [9]. Ravi, K. S.; Venkat, R. G.; Hara, K. K.; Shanthan, R. P.; Narsaiah, B.; Surya, N. M. U. Eur. J. Med. Chem. 2006, 41, 1011‐1016. [10]. Soleiman, H. A. Open Catal. J. 2010, 3, 107‐115. [11]. Dgdyusha, G. G.; Zubarovskii, V. M.; Moreiko, V. M.; Parhomskaya, O. V.; Sych, E. D.; Tikhonov, E. A.; Khodot, G. P. 1978 USSP Patent 568318: Appln: 215763; Chemical Abstract, 1975, 90, 46509j. [12]. Inagaki, Y.; Adachi, K.; Yabe, M. 1988, GerOffen. DE 3819688 (C1G. 11B7124) Appl. 87 143 46809; Chemical Abstract, 1988, 111, 68030a. [13]. Ikeat, T.; Takei, H.; Yamashita, H. 1985, Eur Pat. Appl. Ep. 144091 (1C031128); Chemical Abstract, 1985, 104, 12987. [14]. Sun, S.; Chen, P.; Zheng, D. (Proc. SPIE‐Int. Soc. Opt. Eng. 1998, 3562 (Optical Storage Technology), 11, 16 (Eng.), SPIE. Chemical Abstract, 1999, 130, 175194w. [15]. Onodera, A.; Ninomia, H.; Ghya, H.; Ishibashi, D.; Komamura, T., Katoh, K.; Tanaka, T.; Morimoto, R. (Konica Corporation, Japan). Eur. Pat. Appl. Ep 7C9, 53j (C1CO9B 55100), 23 Apr. 1997. Jp Appl. 96172, 257, 27 Mar 1996, 55 pp. (Eng). Chemical Abstract, 1997, 126, 344433t. [16]. Fabian, J.; Hatmann, H. Light Absorption of Organic Colorants, Springer, 1980, pp. 162‐197. [17]. Rochlitz, J. Chimia 1980, 34, 131‐144. [18]. Alayed, A. S. Can. J. Chem. Eng. 2011, 2, 87‐105. [19]. Alayed, A. S.; Soleiman, H. A. Int. J. Basic App. Sci. 2011, 11, 1‐8. [20]. Pedersen, C. J. Am. Chem. Soc. 1970, 92, 386‐391. [21]. Frensdorff, H. K. J. Am. Chem. Soc. 1971, 92, 4684‐4686. [22]. Sillen, G.; Warnquist, B. Ark. Kemi. 1968, 31, 377‐390. [23]. Ben Othman, A.;Baklouti, L.; Abidi, R.; Vicens, J. Lett. Org. Chem. 2007, 4, 339‐343. [24]. Thabet, W.; Baklouti, L.; Zieba, R.; Parola, S. J. Inclusion Phenom. 2012, 73, 135‐139.