Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 3(1), 86-91, January (2013) Res.J.Chem. Sci. International Science Congress Association 86 Copper(II)-Complexes of an Isatinic Quinolyl Hydrazone-Anion effectHussein S. Seleem*, Mostafa M., Saif M., Amin A. Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo, EGYPTAvailable online at: www.isca.in Received 12th November 2012, revised 19th December 2012, accepted 31st December 2012Abstract New heteroleptic copper(II)- complexes (1:1 or 1:2; M:L) were obtained from the reaction of an isatinic quinolyl hydrazone (HL) with several copper(II)- salts viz. Cl, Br, NO , ClO, SO2- and AcO. The obtained complexes have O, square planar (D4h- symmetry) and square pyramid arrangements. The complexes fulfill the strong coordinating ability of Cl, Br, NO and SO2- anions. Depending on the type of the anion, the ligand coordinates the copper(II)- ions either through its lactam (SO2- and ClO) or lactim forms (the others). For the copper(II)- isatinic complexes the antimicrobial activit shows a gradual change with change of the coordinated anions. Also, depending on the type of the anion, the order of the antimicrobial activity is as follows Cl- � SO2- � Br. Keywords: isatinic quinolyl hydrazones, copper(II)- complexes, anion effect. Introduction Of the several heterocyclic rings, the importance of the quinoline ring arises from its therapeutic and biological activities1,2. Quinolyl hydrazones are known to function as chelating agents and have versatile modes of bonding. Recently, the biological activity of quinolyl hydrazones arises from their tendency to form metal chelates with transition metal ions2-4. On the other hand, the indole ring occurring in Jasmine flowers and Orange blossoms exhibit a wide range of biological activity3,4. The incorporation of the quinoline ring with the indole ring may enhance the biological activity of such class of compounds. In continuation of our interest on the complexation of quinolyl hydrazones3-8, this study is planned to investigate the ligational behavior of the studied hydrazone (scheme 1); 3-[2-(4,6-dimethylquinolin-2-yl) hydrazono]indolin-2-one towards several copper(II)- salts (Cl, Br, NO, ClO, SO2- and AcO). In general, this study exhibit the role of the anion on the isolated copper(II)- complexes; scheme 2. Material and Methods Material: The chemicals used in this investigation were of the highest purity available (Merck, BDH, Aldrich and Fluka). They included CuBr, CuCl.2HO, Cu(NO.2½HO, Cu(ClO.6HO,Cu(AcO).HO and CuSO4 .5HO, toluidine, ethyl acetoacetate, phosphorus oxychloride, isatin and hydrazine hydrate (100%). The solvents used in this study were reagent grade and used without further purification. Measurements: Microanalyses were carried out on a Perkin- Elmer 2400 CHN elemental analyzer. Thermal analyses werecarried out on a Shimadzu-50 thermal analyzer.Electronic spectra were recorded on a Jasco V-550 UV/VIS spectrophotometer. IR spectra were recorded on a Bruker Vector 22 spectrometer using KBr pellets. ESR spectra were recorded on a Bruker Elexsys, E 500 operated at X- band frequency. Mass spectra were recorded at 70 eV on a gas chromatographic GCMSQP 1000-EX Shimadzu mass spectrometer. H NMR spectra were recorded as DMSO-dsolutions on a Varian Mercury VX-300 NMR spectrometer using TMS as a reference. Molar conductivity was measured as DMF solutions on the Corning conductivity meter NY 14831 model 441. Magnetic susceptibility of the complexes was measured at room temperature using a Johnson Matthey, MKI magnetic susceptibility balance. Melting points were determined using a Stuart melting point apparatus. Preparation of the Isatinic Hydrazone (HL): The ligand; 3-[2-(4,6-dimethylquinolin-2-yl)hydrazono] indolin-2-one was prepared according to our previous publication3-6; an ethanolic mixture of 2-hydrazinyl-4,6-dimethyl quinoline (0.01mol) and isatin (0.012 mol) was refluxed for 15 min. The formed scarlet red compound was filtered off, washed with ethanol and crystallized from DMF; Yield: 67% and m.p 290C. Analysis: Calcd. for C19182 (334.3): C, 68.27; H, 5.38; N, 16.76. Found: C, 68.31; H, 5.15; N, 16.40. Preparation of the metal complexes: A methanolic solution of the copper(II)- salt was added gradually to a methanolic solution of the ligand; HL in the mole ratio 1 : 1 ; Cu2+ : HL. The reaction mixture was refluxed for 2-4 h to ensure the complete precipitation of the formed complexes. The precipitated solid complexes (1-6) were filtered off, washed several times with methanol to remove any excess of the unreacted starting materials. Finally, the complexes were washed with ether and dried in vacuum desiccators over anhydrous CaCl. All the isolated complexes are stable at room temperature, non hygroscopic and insoluble in water, partially soluble in alcohols and completely soluble in DMSO and DMF. The molar conductances of 10-3M DMF solutions of the complexes indicate non-electrolytic nature for all complexes except Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(1), 86-91, January (2013) Res. J. Chem. Sci. International Science Congress Association 87 complex 2. The results of elemental and thermal analyses are in good harmony with the proposed structures (table 1). Antimicrobial activity: The standardized disc- agar diffusion method was followed to determine the activity of the synthesized compounds against the sensitive organismsStaphylococcus aureus (ATCC 25923) and Streptococcus pyogenes (ATCC 19615) as Gram - positive bacteria, Pseudomonas fluorescens (S 97) and Pseudomonas Phaseolicola (GSPB 2828) as Gram - negative bacteria. The antibiotics chloramphencol and cephalothin were used as standard reference in case of Gram- negative and Gram- positive bacteria, respectively. The tested compounds were dissolved in dimethyl formamide (DMF) which has no inhibition activity to get concentrations of 2 and 1 mg / mL. The test was performed on medium potato dextrose agar (PDA) which contain infusion of 200 g potatoes, 6 g dextrose and 15 g agar. Uniform size filter paper disks (3 disks per compound) were impregnated by equal volume (10 µL) from the specific concentration of dissolved tested compounds and carefully placed on inoculated agar surface. After incubation for 36 h at 27 °C, inhibition of the organisms which evidenced by clear zone surround each disk was measured and used to calculate the mean of inhibition zones. Results and Discussion Characterization of the hydrazone: The results of elemental analysis of the investigated hydrazone; 3-[2-(4,6-dimethylquinolin-2-yl) hydrazono] indolin-2-one are in good harmony with the proposed formula. The IR spectrum of the hydrazone (table 2) showed broad bands at 3422 / 3162 and very strong band at 1633 cm-1 which are assigned to (OH/NH) and (C=N), respectively. The lactam nature of the hydrazone was supported by a very strong band at 1683 cm-1; (C=O). On the other hand, the electronic absorption spectra of the hydrazone in DMF exhibit two intense bands at 274 and 394 nm characteristic for * transitions. Also, a broad band at 480 nm assignable to charge transfer transition (CT) which impacts the ligand its red color. The higher energy bands are consistent with those reported for the aromatic quinoline ring4,6,8. The mass spectrum of the ligand showed the M peak at m/z = 316 confirming its non hydrated formula weight (316.36) and supporting its suggested structure. Finally, the H NMR spectral data of the ligand in d-DMSO relative to TMS; figure 1, lends a further support of the structure. Table-1 Physical and analytical data of the copper(II)- isatinic complexes No. Reactants L + Cu(II)- salt Complex (F. W.) M.F Yield% Color Elemental Analysis; % Found/(Calcd) C H N 1 Cu(NO 2.2½ H 2 O [Cu (HL) (HL) (NO)] ½ HO (766.01) 38325½Cu 63 Dark brown 59.48 (59.58) 4.03 (4.18) 16.52 (16.45) 2 Cu (ClO.6HO [Cu (HL) (OH] (ClO. ¼HO (935.40) 3836½12¼ClCu 51 Yellowish brown 48.77 (48.79)3.98(3..90) 11.9 (11.98) 3 Cu Cl2 .2HO [Cu (HL) (Cl) (OH)] ½HO.¼MeOH (449.23) 19¼192¾ClCu 55 Red 51.42 (51.46) 4.20 (4. 23) 12.30 (12.47) 4 CuBr[Cu (HL) (Br) MeOH ] (490.78) 2019BrCu 60 Deep red 48.94 (48.94) 3.85 (3.87) 11.72 (11.42) 5 Cu SO 4 .5H 2 O [Cu(HL) (SO) (OH ] 4HO (583.83) 1928SO11Cu 65 Reddish orange 38.99 (39.08) 4.80 (4.79) 9.62 (9.59) 6 Cu (OAc). 2 O [Cu L (OH] 5½HO.¼MeOH (538.77) 19¼329¾Cu 60 Brick red 42.85 (42.91) 5.90 (5..93) 10.38 (10.39) Table-2 Selected IR spectral bands (cm-1) of the ligand and its complexes Other bands (C=N) (C=O) (OH) / (NH) Complex 1633 1683 3422 / 3162 IsatinHQ (N – O); 1332cm - 1 1608 1695 3167 1 (Cl – O); 1115 cm - 1 1615 1705 3278 + 3191 2 1610 _ 3307 3 1609 _ 3295 4  3 (S – O); 1113 cm - 1 1604 1695 3324 5 1606 1559 _ 3170 6 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(1), 86-91, January (2013) Res. J. Chem. Sci. International Science Congress Association 88 Figure-1 H NMR spectrum of the ligand (for aromatic protons d =d =d =d = 6.81 – 7.75) 10203040ControlCuCl2CuBr2CuSO4Cu(OAc)2 S. aureus (2 mg/ml) ComplexInhibition zone 10203040ControlCuCl2CuBr2CuSO4Cu(OAc)2 Inhibition zoneComplex S. pyogenes ( 2 mg/ml)Figure-2 Biological activity of the isatinic complexes Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(1), 86-91, January (2013) Res. J. Chem. Sci. International Science Congress Association 89 Characterization of the complexes: For examining the role of the anions on the formed products, the ligand was allowed to react with several copper(II)- salts viz. Cl, Br, NO, SO, ClO and AcO (scheme 2). The obtained copper(II)- complexes reflect the strong coordinating power of SO, Cl, Br and NO as compared to the non coordinating power of ClO. This is consistent with the donor ability of the anions10; (DN = 36.2, 33.7, 21.1 and 8.44 for Cl, Br, NO and ClO, respectively). The isatinic hydrazone has mainly two tautomeric forms (scheme 1); the lactam- lactim forms are useful in explaining the different coordinating properties. The obtained complexes are mononuclear and heteroleptic. In complex 6, the acetate anion acts as a base enough to deprotonate the ligand. The obtained complexes have the octahedral (O), square pyramid and square planar (D4h) geometries; (scheme 2). The isatinic hydrazone (HL) behaves as dianionic, monoanionic or neutral NNO- or NO- donor. Depending on the type of the anion, the ligand uses its lactam (SO and ClO) or lactim forms (the others). In case of the NO anion, the ligand uses a mixed mode; lactam / lactim (complex 1). Characterization of the obtained complexes was achieved via elemental and thermal analyses, magnetic and conductivity measurements as well as spectral studies. IR spectra of the complexes: The mode of bonding was studied by comparing the IR spectral bands of the metal complexes with those of the free ligand (table 2). Inspection of the data revealed the following: i. All complexes showed a broad band in the range 3342-3167 cm-1 due to (OH) of the associated water or methanol molecules. ii. The band located at 1633 cm-1assignable to the (C=N) in the free hydrazone was shifted to lower values confirming its participation in the chelation. iii. For complexes (3, 4 and 6), the band located at 1683 cm-1 due to (C=O) of the free ligand disappeared indicating the participation of the lactim- form in the chelation. In contrast, the lactam- form participates in the chelation in case of the nitrato (1), perchlorato (2) and sulfato (5) complexes as indicated by the shift of the above band to higher wave numbers; lactam- complexes indicate - electron delocalization i.e. resonance stabilization in the formed chelate ring10 (table 2). iv. In complex 2, The ionic nature of the ClO anion is supported by the appearance of strong antisymmetric stretch band11 at 1115 cm-1; (Cl-O). This is consistent with the electrolytic nature of complex. v. For the sulfato complex (5), the chelating bidentate nature of the SO group is indicated by the appearance of (S-O) strong band at 1113 cm-1characteristic for the high symmetry T (tetrahedral) point group. vi. The nitrato complex (1) showed a band at 1332 cm-1confirming the monodentate nature of the coordinated NOgroup; C2v symmetry11. Conductivity, magnetic properties and electronic spectra: The recorded conductance for 10-3 molar DMF solutions of the complexes indicates that all complexes are non- conducting due to their neutrality. The only exception is the perchlorato complex (2) which showed molar conductance of 173 -1 cmmol-1, indicating its 2:1 electrolytic nature which is consistent with the IR spectra; (Cl-O) at 1115 cm-1. On the other side, the effective magnetic moments (eff) of the copper(II)- complexes (1-6) lie in the range 2.10-1.79 B.M. which is consistent with one unpaired electron and falls within the range reported for mononuclear copper(II)- complexes12,13. On the other side, the electronic spectra of the complexes as DMF solutions showed a new intense broad band in the range 505 – 519 nm confirming its charge transfer (CT) nature. Therefore, the type of the d-d transitions cannot be identified due to the strong CT bands tailing from UV region to the visible region12. In general, the color of all complexes is dominated by the CT transition which obscured the weak d-d transition occurring in the same region; a phenomenon encountered with isatinic complexes4,6. Also, the electronic spectra of all complexes are nearly similar in terms of the position, intensity and shape of the bands. ESR Spectra: For obtaining further information about the stereochemistry and bonding of the complexes14, the room temperature ESR spectra of the powder solid complexes were recorded for complexes 4 and 5 as representative examples. The ESR spectra of the sulfato complex; [Cu(HL)(SO)(OH].4HO () showed two types of resonance components, one set is due to the parallel(11) features and the other set due to perpendicular() features in consistency with axial symmetry supporting its octahedral geometry. Inspection of the data reveals that; g11 � g� 2.0023, corresponding to the presence of the unpaired electron in the dorbital. However, the unpaired electron is not located in the orbitals of identical composition due to the delocalization of the d- electron towards the ligand donor atoms. On the other hand, the complex; [Cu(HL)(Br)].MeOH () showed a broad signal with giso = 2.153 suggesting its square planar geometry. The ESR spectral profiles reflect the non equivalence of the environment around copper(II)- ions. Thermal analysis: The thermal degradation behavior of the investigated complexes (1, 2, 5, 6) was followed by thethermogravimetric (TG) technique. The decomposition occurs in several steps according to the nature of each complex. Attempts to generalize the thermal degradation patterns were unsuccessful indicating that there is no simple relation or general trend for explaining these thermal degradations. However, the decomposition ends with the formation of CuO in case of complexes (1, 2). Inspection of the thermograms reveals the following: i. The thermogram of complex (2) showed a high degree of the thermal stability as indicated by its first step of decomposition. Ii. For the complexes (5, 6), the decomposition is not completed up to 800°C, indicating strong metal - ligand bonds. Antimicrobial activity: The antibacterial activity of the ligand and its metal complexes was summarized in table 3 and represented graphically in figure 2. Inspection of the data reveals the following: The ligand and its complexes 1 and 2 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(1), 86-91, January (2013) Res. J. Chem. Sci. International Science Congress Association 90 have no activity towards the studied organisms; Gram- positive bacteria (S.aureus and S. pyogenesand Gram- negative bacteria P.phaseolicola and P.fluoresces). For the copper(II)- isatinic complexes the antimicrobial activity shows a gradual change with change of the coordinated anions4,6. The order is as follows Cl- � SO2- � Br � nil. This order confirms that the nature of the coordinated anions plays a significant role on the inhibition of the bacteria growth. NH N N OH N NH N OH N NH OH N NH NN OH Lactim- forms Lactam- formsScheme-1 Tautomeric forms of 3-[2-(4,6-dimethylquinolin-2-yl)hydrazono] indolin-2-one NH O N N H N NH O N N NH Cu S O O O OHOH N N O N NHCu Y Cu N N N N O OH OH NH N N O N Cu O NH N N NH ONO NH O N N NH O NH N N NH CuOH H2O (ClO H2O CuX CuSO Cu(NO Cu(AcO) Cu(ClO No. X Y(3) Cl H(4) Br MeOH (1) (2) (5) (6)Scheme-2 Copper(II)- complexes of 3-[2-(4,6-dimethylquinolin-2-yl)hydrazono] indolin-2-one Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 3(1), 86-91, January (2013) Res. J. Chem. Sci. International Science Congress Association 91 Table-3 Antimicrobial activity of IsatinHQ and its complexes Organisms Mean* of zone diameter , nearest whole mm. Gram - positive bacteria Gram - negative bacteria S. aureus S. pyogenes P. Phaseolicola P. fluorescens Concn. Complexes 2 mg /ml 1mg /ml 2 mg /ml 1mg /ml 2 mg /ml 1mg /ml 2 mg /ml 1mg /ml IsatinHQ _ _ _ _ _ _ _ _ [Cu (HL)(Cl)(H 2 O)] ½H 2 O ¼MeOH (3) 21 12 17 14 7 6 10 12 [Cu (HL)(Br)] MeOH (4) 12 7 14 11 6 6 8 5 [Cu (H 2 L)(SO 4 )( OH 2 ) 2 ] 4 H2O (5) 16 13 17 12 _ _ _ _ [Cu L (OH 2 ) 3 ] 5½H 2 O .¼MeOH (6) 8 5 6 4 4 4 5 4 Control # 42 28 38 30 36 25 38 30 Conclusion The ligational behavior of the isatinic hydrazone ligand as well as the geometry of the isolated complexes (O, D4h and square pyramid) is highly affected by the type of the anion. Also, depending upon the type of the anion, the antimicrobial activity shows a gradual change with change of the coordinated anions4,6. References 1.Finar I.L., Organic Chemistry. 6th ed, Hong Kong, The Continental Printing Co. Ltd. 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