Accepted Manuscript Synthesis, characterization and biological activity of 2-acetylpyridine-α-naphthoxyacetylhydrazone its metal complexes O.A. El-Gammal, M.M. Bekheit, Mai Tahoon PII: DOI: Reference:

S1386-1425(14)00862-2 SAA 12233

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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Received Date: Revised Date: Accepted Date:

3 March 2014 16 May 2014 28 May 2014

Please cite this article as: O.A. El-Gammal, M.M. Bekheit, M. Tahoon, Synthesis, characterization and biological activity of 2-acetylpyridine-α-naphthoxyacetylhydrazone its metal complexes, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2014), doi:

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Synthesis, characterization and biological activity of 2-acetylpyridine-α-naphthoxyacetylhydrazone its metal complexes O. A. El-Gammal*M.M. Bekheit, and Mai Tahoon Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, P.O.Box 70, Mansoura- Egypt Abstract A new series of complexes of Ni(II), Co(II), Cu(II), Cd(II), Mn(II), Hg(II) and UO22+ derived from2-acetylpyridine-α-naphthoxyacetylhydrazone (HA2PNA) have been prepared and characterized by elemental analyses, spectral (IR, UV-visible, ESR and


HNMR) as well as magnetic and thermal

measurements. The data revealed that the ligand acts asneutral NO, NN and NNOor mono-negative NNO chelate. On the basis of electronic spectral and magnetic moment data, an octahedral geometry is suggested for Mn (II), Co (II), Ni (II) and UO22+ complexes and a square planar arrangement for Cu (II) complex.The bond length, bond angle, HOMO, LUMO, dipole moment and charges on the atoms have been calculated to confirm the geometry of the ligand and the investigated complexes. The kinetic parameters were determined for thermal degradation stages of some complexes using Coats-Redfern and Horowitz-Metzger methods. Also, the ligand and its complexes were screened against antibacterial, antioxidant using DPPH radical and antitumor activities using in vitro Ehrlichascites assay. Key words: Hydra zone, spectral characterization, DFT molecular modeling, DPPH antioxidant and Ehrlich ascites Carcinoma. e-mail: : [email protected]

Tel: 002-0126712958

Introduction: Hydrazones are a versatile class of compounds which present innumerous chemical and pharmacological applications. They have shown to possess antimicrobial, anticonvulsant, analgesic, anti-inflammatory, antiplatelet, antitubercular, antihypertensive agent antitumor properties [1-4]. Moreover, aromatic hydrazone molecules dispersed in a binder polymer are used as the main constituent of electrophotographic photoreceptors of laser printers [5].Also, hydrazones are used for extraction of some metal ions in different buffering solutions [6, 7], determination of titanium in bauxite, Portland cement and granites [8].Metal complexes of hydrazones proved to have potential applications as catalysts [9], luminescent probes [10] and molecular sensors [11]. Furthermore, some 2-formylpyridine derived hydrazones which behaves as iron chelators were suggested as therapeutic agents for treatment of 1

neurogenerative disorders [12].So this work aims to investigate the chelating properties of 2Acetylpyridine-α-naphthoxyacetylhydrazone (HA2PNA) towards some transition metal ions in more details, including molecularstructures of both ligand and its transition metal complexes, thermal behavior, the antibacterial activity against Bacillus thuringiensis (B.t.) as Grampositive bacteria and Pseudomonas aeuroginosa (P.a.) Gram negativebacteria using the inhibitory zone diameter.Also, the antioxidantactivity evaluated using total antioxidant capacity radicalassays (DPPH• - 2,2’-diphenyl-1-picrylhydrazyl radical and cytotoxic activities of the compounds have been discussed. 1. Experimental. 2.1 . Instrumentation and materials All the chemicals were purchased from Aldrich and Fluka and used without further purification. Elemental analyses (C, H and N) were performed with a Perkin-Elmer 2400 series II analyzer. The determination of metal and chloride contents in complexes was carried out according to the standard methods.IR spectra (4000–400 cm−1) for KBr discs were recorded on aMattson 5000 FTIR spectrophotometer. Electronic spectra were recorded on a Unicam UV–Vis spectrophotometer UV2. Magneticsusceptibilities were measured with a Sherwood scientific magneticsusceptibility balance at 298 K. 1H-NMR measurements in DMSO-d6 at room temperature were carried out on a Varian GeminiWM500MHz








measurements (TGA, DTA, 20–800˚C) were recorded on a DTG-50 Shimadzu thermogravimetric analyzer at a heating rate of 15◦C/min and nitrogen flow rate of 20 ml/min. A powder ESR spectrumwas obtained in a 2 mm quartz capillary at room temperature with a Bruker EMX spectrometer working in the X-band (9.78 GHz) with 100 kHz modulation frequency. Themicrowavepower and modulation amplitudes were set at 1mWand 4G, respectively. The low field signal was obtained after fourscans with 10-fold increase in the receiver again. 2.2. Synthesis of 2-Acetylpyridine-α-naphthoxyacetylhydrazone (HA2PNA) α-naphthoxyacetylhydrazine was synthesized by the literature method [13]. HA2PNA was prepared by heating equimolar amounts of 2-acetylpyridine (11 ml, 0.1mol) and α-naphthoxyacetylhydrazine (23.4 gm, 0.1mol) in 150 ml absolute ethanol under reflux for 2 hours. On cooling, pale yellow precipitate was formed, filtered off, washed, recrystallized from absolute ethanol and finally dried in a vacuum desiccator over anhydrous calcium chloride. The pale yellow powder is 2-acetylpyridine-α-naphthoxyacetyl hydrazone (HA2PNA) (Scheme 1).Yield ≈ 25.4 gm, m.p. 180-183˚C.Anal.Calc. for : C71.46, H5.37; Found: C71.38 , H 5.42.Main IR bands (KBr, cm-1): 3201(m) ν (NH), 1695(s) ν(C=O), 1626ν(C=N)(br), 1581ν(C=N)py, 1153(s) ν(N-N); UV(DMSO, cm-1):λmax=36423,33783.1H NMR (DMSO-d6; δ, ppm)(Fig.1S, Supplementary material): δ = 11.05ppm (s, 1H, NH); 5.02 (s, 2H, CH2); 2.30 (s, 3H, CH3); pyridine ring protons appeared at δ:8.62 ppm {(m, 2H, H–C16=H–C17, J=7.50Hz),(H–C16=H– 2

C20.J=1.5,H–C17=H–C16, j=7.5 Hz)}, δ:8.50 ppm{(d, 2H, H–C19=H–C20, J=7.5 Hz), : 8.2{ 2H, H– C17=H–C18)} and δ:7.80 ppm {(d, 2H, H–C20=H–C17, J=7.5 Hz)},( H–C20=H–C19, j=7.5 Hz)}; naphthyl protons appear at δ:7.66ppm{( dd, 2H, H–C10=H–C5, (H–C9=H–C10, J=7.50, 1.50 Hz)}, δ:7.64{(dd, 2H, H–C9=H–C10,J=7.50, 1.50 Hz ),(H–C8=H–C9, J=7.50, 1.50 Hz), δ:7.50ppm{dd,H– C8=H–C7,H–C9=H–C8, J=7.50 Hz)} δ:7.42ppm{(dd, 2H, H–C1=H–C2, ),(H–C1=H–C3, J=7.50, 1.50 Hz), δ:7.40ppm {(dd, 2H, H–C3=H–C2,J=7.50, 1.50 Hz ),(H–C2=H–C3, J=7.50, 1.50 Hz) and δ:6.90ppm {(dd, 2H, H–C1=H–C2, ),(H–C1=H–C3, J=7.50, 1.50 Hz), respectively.

(Scheme 1) 2.3. Synthesis of metal complexes The metal complexes were prepared (Scheme 2) by reacting Schiff base ligand (HA2PNA) (0.319 g, 1.0 mmol) in ethanol (20 ml) with the corresponding metal chloride / acetate (1.0 mmol) in ethanol (20 ml). The reaction mixture was heated under reflux for 1-2 h on a water bath. The colored precipitates formed were filtered off, washed with alcohol followed by complexes were diethyl ether and dried in a vacuum desiccator over anhydrous CaCl2. The physical and analytical data of the isolated complexes are listed in Table 1. (i) MCl2 + HA2PNA


[M(HA2PNA)Cl2(H2O)n] {M=Ni(II), Co(II), Mn(II), Cd(II), Hg(II) and Cu(II), n=0-2}

reflux ,2h

(ii) UO2(CH3COO)2 + HA2PNA

C2H5 OH, CH3COONa reflux, 1h

[UO2(A2PNA)2] + 2CH3COOH

(Scheme 2) a)




230˚C;Anal.Calc.:C47.53, H4.36, Ni12.10, Cl 14.62; Found: C47.53, H 4.72, Ni 12.10, Cl14.85; Λam in DMSO


ohm-1 cm2 mol-1: 53. Main IR peaks (KBr,cm-1):3173 (m) ν (NH), 1660 (s) ν(C=O),

1592ν(C=N)(br), 1579 ν(C=N)py, 1166 (s) ν(N-N), 490 ν(M-O), 424 ν(M-N); UV–Vis (DMF, cm-1) :λmax: 14577, 23809, µeff (B.M.)3.2. 3





˚C;Anal.Calc.: C47.03, H4.36, Co 12.14, Cl14.61; Found: C47.48, H4.69, Co 12.70, Cl15.25; Λam38. Main IR peaks (KBr, cm-1): 3199 (m) ν(NH), 1658 (s)ν(C=O), 1595 ν(C=N)(br), 1578 ν(C=N)py, 1158 (s) ν(N-N), 490 ν(M-O), 420 ν(M-N) ; UV–Vis (DMF, cm-1) :λmax: 14492, 17241, µeff(B.M.) 4.0. c)

[Mn(HA2PNA)Cl2(H2O)], MnC19H19N3O3Cl2, chare at 260˚C; Anal.Calc.: C49.26, H4.13, Mn11.86, Cl15.31; Found: C 49.18, H4.27, Mn12.02, Cl `15.53; Λam:48. Main IR peaks (KBr, cm-1): 3137(m) ν (NH), 1671 (s) ν(C=O), 1634ν(C=N)(br), 1591ν(C=N)py, 1163 (s) ν(N-N), 499ν(M-O), 420 ν(M-N) ; UV–Vis (DMF, cm-1) :λmax: 20833,22222, µeff (B.M.) 5.4.




CdC19H19 N3O3Cl2, a

270˚C; Anal.Calc.: C43.83, H3.68, Cd21.59, Cl13.62; Found: C43.64, H3.46, Cd 12.10, Cl14.85; Λ m:38.

Main IR peaks (KBr, cm-1): 3171(m) ν (NH), 1684(s) ν(C=O), 1634ν(C=N)(br), 1589ν(C=N)py, 1164(s) ν(N-N), 499ν(M-O), 420ν(M-N).1H NMR(Fig.2S, Supplementary material): δ = 11.45ppm (s, 1H, NH); 5.06(s, 2H, CH2); 3.44 (s, 3H, CH3); pyridine ring protons appeared at δ:9.11 ppm {(m, 2H, H– C16=H–C17, J=7.50Hz),(H–C16=H–C20.J=1.5,H–C17=H–C16, j=7.5 Hz)}, δ:8.48 ppm{(d, 2H, H– C19=H–C20, J=7.5 Hz), : 8.44{ 2H, H–C17=H–C18)} and δ:8.38 ppm {(d, 2H, H–C20=H–C17, J=7.5 Hz)},( H–C20=H–C19, j=7.5 Hz)}; naphthyl protons appear at δ:8.01ppm{( dd, 2H, H– C10=H–C5, (H–C9=H–C10, J=7.50, 1.50 Hz)}, δ:7.97{(dd, 2H, H–C9=H–C10,J=7.50, 1.50 Hz ),(H– C8=H–C9, J=7.50, 1.50 Hz), δ:7.62ppm{dd,H–C8=H–C7,H–C9=H–C8, J=7.50 Hz)}; δ:7.59 ppm{(dd, 2H, H–C1=H–C2, ),(H–C1=H–C3, J=7.50, 1.50 Hz), δ:7.53 ppm {(dd, 2H, H–C3=H– C2,J=7.50, 1.50 Hz ),(H–C2=H–C3, J=7.50, 1.50 Hz) and δ:7.14 ppm {(dd, 2H, H–C1=H–C2, ),(H– C1=H–C3, J=7.50, 1.50 Hz), respectively. e)






Anal.Calc.:C38.62, H2.90, Hg33.95, Cl12.00; Found:C38.34, H 2.73, Hg 34.25, Cl11.91; Λam: 2. Main IR peaks (KBr, cm-1): (m) 3173 ν (NH), 1685 (s) ν(C=O), 1630ν(C=N)(br), 1583 ν(C=N)py, 1160 (s) ν(N-N), 490 ν(M-O), 427 ν(M-N). f)

[Cu(HA2PNA)Cl2] CuC19H17N3O2Cl2, m.p. 230˚C; Anal.Calc.

C47.53, H4.36, Ni 12.10, Cl 14.62; Found: C47.53, H 4.72, Ni 12.10, Cl14.85; Λam in DMSO in ohm1

cm2 mol-1: 53. Main IR peaks (KBr, cm-1): 3173 (m) ν (NH), 1660 (s) ν(C=O), 1592ν(C=N)(br),

1579 ν(C=N)py, 1166 (s) ν(N-N), 490 ν(M-O), 424 ν(M-N) ; UV–Vis (DMF, cm-1) :λmax: 14577, 23809, µeff(B.M.)3.2. 2.5.Biological studies 2.5.1. Antibacterial Activity


The in vitro antibacterial of the reported complexes was evaluated against Bacillus thuringiensis (B.t.) as Gram positive bacteria and Pseudomonas aeuroginosa (P.a.) Gram negative bacterial cultures using Streptomycin as standard control .The hole plate diffusion method [14] was adopted for the activity measurements. The bacterial strains were grown in nutrient agar slants. A suspension of the studied compounds (0.2 ml of each (10 µg/ml) was incubated at 36oC for 36 h for the bacterial culture. After inoculation, the diameter (in mm) of the clear inhibition zone surrounding the sample is taken as a measure of the inhibition power against the particular organisms. The experiments were repeated three times and the values recorded are the mean average. 2.5.2. Antioxidant activity DPPH free radical scavenging activity The hydrogen atom or electron donation ability of the corresponding compounds was measured from the bleaching of purple colored of the methanol solution of DPPH. This spectrophotometric assay uses the stable radical diphenylpicrylhydrazyl (DPPH) as a reagent [15, 16]. Different concentrations of the chemical compounds were dissolved in methanol to obtain final concentration ranged from 6.25 to 200 mg/mL to determine IC50 (concentration makes 50% inhibition of DPPH color). Fifty microliters of various sample concentrations were added to 5 ml of 0.004% methanol solution of DPPH. After a 60 min of incubation at dark, the absorbance was read against a blank at 517 nm. Inhibition percent of free radical DPPH was calculated according to the equation: I% = (Ablank – Asample) / (Ablank) ×100 Where Ablank is the absorbance of the control reaction (containing all reagents except the test compound), and Asample is the absorbance of the test sample. Cytotoxic activity Ehrlich cells Ehrlich cells (Ehrlich ascites Carcinoma, EAC) were derived from ascetic fluid from diseased mouse (the cells were purchased from National Cancer Institute, Cairo, Egypt, which is a certified Institute by National Medical Research Ethics Committee). DNA (Calf Thymus type1), bleomycin sulfate, butylated hydroxyl anisole (BHA), thiobarbituric acid (TBA), ethylenediaminetetraacetic acid (EDTA) and ascorbic acid were obtained from sigma. 2, 20-azo-bis-(2-amidinopropane) dihydrochlorid (AAPH), 2, 20-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) were purchased from Wako Co., USA. Antioxidant activity screening assay for erythrocyte hemolysis The blood was obtained from rats by cardiac puncture and collected in heparinized tubes. Erythrocytes were separated from plasma and the buffy coat was washed three times with 10 volumes of 5

0.15 M NaCl. During the last wash, the erythrocytes were centrifuged at 2500 rev. / min for 10 min to obtain a constantly packed cell preparation. Erythrocyte hemolysis was mediated by peroxyl radicals in this assay system [17]. A 10% suspension oferythrocytes in phosphate buffered saline pH 7.4 (PBS) was added to the same volume of 200 mMAAPH solution in PBS containing samples to be tested at different concentrations. The reaction mixture was shaken gently while being incubated at 37 °C for 2 h. The reaction mixture was then removed, diluted with eight volumes of PBS and centrifuged at 1500g for 10 min. The absorbance of the supernatant was read at 540 nm. Similarly, the reaction mixture was treated with 8 volumes of distilled water to achieve complete hemolysis, and the absorbance of the supernatant obtained after centrifugation was measured at 540 nm. The data percentage hemolysis was expressed as mean ±standard deviation. L-ascorbic acid was used as a positive control. Antitumor activity using Ehrlich ascites in vitro assay Different concentrations of the tested compounds were prepared (100, 50 and 25 ml from 1 mg/ml in DMSO (g⊥(2.069) >2.0023 indicating that the copper site has a d x2-y2 ground-state characteristic of square planar or octahedral stereochemistry [38]. In axial symmetry, the g-values are related by the expression, G = (g||– 2)/(g⊥–2) = 4. According to Hathaway [39], as value of G is greater than 4, theexchange interaction between copper (II) centers in the solid state is negligible, whereas when it is less than 4, a considerable exchange interaction is indicated in the solid complex. The calculated G value for the copper complex (3.635) is less than 4 suggestingcopper–copper exchange interactions. A forbidden magnetic dipolar transition for [Cu(HA2PNA)Cl2] is observed at half-field (ca. 1600 G, g ≈ 4.0) but the intensity is very weak.In order to quantify the degree of distortion of the copper (II) complex, we calculated the f-factor (g||/A||) which is considered as an empirical index of tetrahedral distortion [40] and found to be177, which is characteristic for high distortion and supports the coordination through enolato-oxygen which in turn enforces the structure to remain in a nearly octahedral geometry [40]. This is in accordance with the weak bond between the axial pyridine nitrogen and the copper (II) ion as determined by molecular modeling. Molecular orbital coefficients, α2 (a measure of the covalence of the in-plane σ-bonding between a copper 3d-orbital and the ligand orbitals) and β2 (covalent in-plane π-bonding), were calculated by using the following equations [41]: 11

α2 = (A||/0.036) + (g|| – 2.0023) + 3 (g⊥ – 2.0023)/7 + 0.04 β2 = (g|| – 2.0023)E/ – 8λα2 Where λ=-828 cm–1 for the free copper ion and E is the electronic transition energy. The observed values of α2 (0.35) and β2(0.61) for of the complex are less than unity and slightly higher than 0.5, which indicates that the in-plane σ-bonding and in-plane π-bonding are appreciably covalent and again supports the fact that enolato oxygen binding in the present copper complex incorporates significant covalence in the metal-ligand bonding through delocalized dπ—pπ in plane π-bonding. For the octahedral complexes, the lower value of β2 compared to α2 indicates that the in-plane π-bonding is more covalent than the inplane σ-bonding. 3.4. Thermogravimetric studies. The structural characterization of the investigated complexes was further delivered by a careful examination of their thermogravimetric, TG patterns. A glance at the data obtained in Table11S (Supplementary materials) and the TG thermogram of the complexes (Fig.1) shows that the complexes have stability range from ambient temperature to 138oC. TG of some complexes represented two decomposition stages while others represented three or four decomposition stages. In the two stage decomposition process, the first stage generally occurred in 138-244 oC range presumably due to loss of chloride, coordinated water and mixed ligand fragments. The second stage that started later occurred in the temperature range 506-528 oC and continued until the complete decomposition of the ligand ultimately leaving either the metal or the metal oxide as the residue. In the three or four stage decomposition process the final step exhibits complete decomposition of the ligand moiety leaving also a residue as metal oxide. 3.5. Kinetic data. In order to assess the influences of the structural properties of the chelating agent and the type of the metal on the thermal behavior of the complexes, the order (n) and the heat of activation Ea of the various decomposition stages were determined from the TG and DTG using the coats-Redfern [42] and HorowitzMetzger [43](Figs. 2a-2h). The obtained data were in Tables 4 and 5.The rate of thermal decomposition of a solid ( dα ) expressed by the Arrhenius equation has the following form: dt

dα  E  = A exp − a  g (α ) dt  RT 


Where Ea is the activation energy, A is the Arrhenius pre-exponential factor, R is the gas constant and g(α) is the differential conversion factor and equal (1-α)n where n is the reaction order, assumed to remain constant during the reaction[44, 45]. A large numbers of decomposition processes can be 12

represented as first order reaction, particularly, the degradation of the investigated series of metal complexes. Under this assumption the integration of equation (1) leads to:

ln(1 − α) = −

E A T Exp(− a ) dT ∫ βT RT o


On the basis of equation (2), it is possible to analyze experimental data by the integral method, in order to determine the degradation kinetic parameters A, Ea.The other thermodynamic parameters of activation can be calculated by Eyring equation [46, 47]. From the results obtained, all decomposition steps show best fit for n = 1 and the negative value of ∆S*(entropy of activation) of some decomposition steps indicates that the activated fragments have more ordered structure than the undecomposed ones and the later are slower than the normal. The positive sign of∆H*(activation enthalpy change) indicates that the decomposition stages are endothermic processes.The high values of Ea of the complexes reveal the high stability of such chelates in the order: Mn(II)complex>Co(II)complex>Cu(II) complex because the radius of the cation decrease and this leads to stronger covalent bond between central metal ion and the hetero atom of the ligand [48].The positive sign of ∆G* for the investigated complexes reveals that the free energy of the final residue is higher than that of the initial compound, and hence all the decomposition steps are nonspontaneous processes. The negative values of ∆S for the degradation process indicates more ordered activated complex than the reactants or the reaction is slow [46]. 3.6. Biological studies. 3.6.1. Antibacterial activity The zone of inhibition was measured in mm and the values of theinvestigated compounds are summarized in Table 6.The values indicate that the ligand as well as its metal complexes had no activity against the Gram +ve, P.a. Cu(II), and Co(II) and Ni(II) complexes showed an inhibition activity higher than the ligand and other complexes against the Gram +ve, B.t. organism. Such increased activity of the metal complexes can be explained on the basis of the Overtone concept and chelation theory [47]. According to the overtone concept of cell permeability, the lipid membrane that surrounds the cell favors the passage of only lipid soluble materials, due to which lipid solubility is an important factor controlling the antimicrobial activity. On chelation, the polarity of the metal ion is reduced to a great extent due to the overlap of the ligand orbital and the partial sharing of the positive charge of the metal ion with donor groups. Furthermore, it increases the delocalization of electrons over thewhole chelate ring and enhances the lipophilicity of the complex. This increased lipophilicity enhances the penetration of the complex into the lipid membrane and blocks the metal binding sites on the enzymes of the microorganism. 13

3.6.2.DPPH free radical scavenging activity. In this study, Cu(II), Ni(II), and Co(II) complexes were found to bemuch better DPPH radical scavengeramong the studied compounds with IC50 :7.89, 7.93 and 7.97 mg/ml comparable with ascorbic acid(Table7) followed by U(VI)O2 and Mn(II) complexes with IC50 11.06 and 11.55 mg/ml respectively. HA2PNA and Cd(II) complex exhibited moderate scavenging activity while Hg(II) complex showed very weak activity with IC50of 62.25. The IC50 valueswere determined for all compounds and reported in Fig.3. 3.6.3.Antitumor activity using in vitro Ehrlich ascites assay The ligand, HA2PNA and its complexes were screened for their antitumor activity (Table 7).U(VI)O22+, Cd(II) and Mn(II) complexes proved to have the highest cytotoxic activity ( 81.0 %,69.00 % & 68.0) while Co(II) complex and HA2PNAhave the moderate cytotoxic activity(65.1, 65.0, 63.9%& 65.1%)comparable to 5-furacil (standard drug). Ni(II) and Hg(II) complexes exhibited weak cytotoxic activity.The variation of % inhibition of Ehrlich antitumor activity with concentrationof test compounds is shown in Fig.4. 3.6.4.Antioxidant activity screening assay for erythrocyte hemolysis. All compounds were tested for antioxidant activity as reflected by rate erythrocyte hemolysis.A glance at Table 8 indicated that the activity of the compounds under investigation decreases in the order: Ni(II)> U(VI)O22+>Cu(II) complex >Mn (II) complex >Hg(II) >Co(II) >Cd(II) >HA2PNA.

3.6.5.Structure activity relationship (SAR). i.

In scavenging activity assay of the investigated compounds,the potent antioxidant activity of Cu(II), Co(II) and Ni(II) may be referred tothe fact that there still one (C=N)pyridine, one NH and O-naphthoxy free groups in the hydrazone, moiety (HA2PNA)[48].


In Cu(II) complex, there are one NH and C=O free groups that can donate an electron or hydrogen radical thus be converted into a stable diamagnetic molecule[49].


The activityof Mn(II) andU(VI)O22+ complexes may be due to the presence of onefree NH group in the first complex and two oxygen atoms in O=U=O moiety in addition to oneacetate group which enhances the scavenging activity in the second complex. Also, the moderate activity of the hydrazone, HA2PNA and Cd(II) complex can be explained in terms of is steric hindrance asthe molecule has oriented itself in a manner that prevents the NH group to be an electrondonating group. The main factor controlling the antioxidant activity the extent of availability of NH groups as electron donor or hydrogen radical. 14


Hg(II) complex showed no activity owing to its well-known high toxicity although most of the donor sites free otherwise C=O and (C=N) imine groups.

Conclusion 2-acetylpyridine-α-naphthoxyacetylhydrazone exhibits a range of considerable structural versatility that give rise to useful biological activity. Thus Ni(II), Co(II), Cu(II), Cd(II), Mn(II), Hg(II) and U(VI)O22+ complexes have been prepared and characterized assigning an octahedral geometry. The kinetic parameters of thermal degradation of some metal complexes were evaluated using Coats-Redfern and Horowitz-Metzger methods. Moreover, the ligand and its complexes were screened for antibacterial, antioxidant activity (using DPPH radical), erythrocyte hemolysis and in vitro Ehrlich as cites assay. It is observed that the antibacterial activity was enhanced on chelation. Ni (II) showed the potent erythrocyte hemolysis whileU(VI)O22+complex showed the potent in vitro Ehrlich .On the hand the, Cu (II) exhibited the highest antioxidant activity using DPPH and ABTS. The structure activity relationship was discussed. References [1] S.Rollas, Ş.G.Küçükgüzel, Molecules, 12 (2007) 1910. [2] H.J.C.Bezerra-Netto, D.I.Lacerda, A.L.P.Miranda, H.M.Alves, E.J.Barreiro, C.A.M.Fraga, Biorg. Med. Chem., 4 (2006) 7924. [3] L. Mazur, B. M.Banachiewicz, R. Paprocka , M.Zimecki, U. E. Wawrzyniak, J.Kutkowska , G. Ziółkowska, J. Inorg. Biochem., 114 (2012) 55-64. [4] T. H. Rakha, O. A. El-Gammal, H. M. Metwally, G. M. A. El-Reash, J. Mol. Struct., 1062 (2014) 96109. [5] V.Getautis, M.Daskeviciene, T.Malinauskas, V.Jankauskas, J.Sidaravicius, Thin Solid Films, 516 (2008) 8979. [6] S.Sivaramaiah, P.A.Reddy, J. Anal. Chem., 60 (2005) 828. [7] S. E. Ghazy, G. M. Abu El-Reash, O.A. El-Gammal, T.Yousef, Chem. Spec. Bioavail., 22 (2010) 127. [8] O. A. El-Gammal, T. H. Rakha, H. M. Metwally, G. M. A. El-Reash, Spectrochimica Acta A, 127 (2014) 144-156. [9] Z. Chen , Y. Wu, D. Gu , F. Gan, Spectrochimica Acta A, 68 (2007) 918-926. [10] O.Pouralimaradan, A.C.Chamayou, C.janiak, H. Monfared, Inorg. Chim. Acta, 360 (2007) 1599. [11] C.Basu, S.Chowdhury, R.Banerjee, H.S.Evans, S.Mukherjee, Polyhedron, 26 (2007) 3617. [12] M.Bakir, O.Green, W.H.Mulder, J. Mol. Struct., (2008) 17. [13] M.whitnall, D.R.Richardson, Semin. Pediatr. Neurol., 13 (2006) 186. [14] K. Gewald, I. Hofmann, J. Prakt. Chem., 311 (1969) 402. [15] C. H. Collins, P. M. Lyne, R. D. Gillard, J. A. McCleverty, Microbiological Methods, Univeristy Park Press, Baltimore, MD, 1970. 15

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Figure 2 Coats-Redfern plot of first degradation step for: (a)[Co(HA2PNA)(H2O)2Cl2] (b)[Cu(HA2PNA)Cl2] (c)[Mn (A2PNA)Cl2(H2O)] (d) [Cd(HA2PNA)(H2O)Cl2]

Horowitz-Metzger plot of first degradation step for: (e)[Co(HA2PNA)(H2O)2Cl2] (f)[Cu(HA2PNA)Cl2] (g)[Mn (A2PNA)Cl2(H2O)] (h) [Cd(HA2PNA)(H2O)Cl2].



(c )


Fig.1.Thermal analysis curves of : (a)[Co(HA2PNA)(H2O)2Cl2] (b)[Cu(HA2PNA)Cl2] (c)[Mn (A2PNA)Cl2(H2O)] (d) [Cd(HA2PNA)(H2O)Cl2 ]

Fig.3: DPPH scavenging activity spectrophotometric assay of various concentration of HA2PNA and its complexes.

Fig. 4 Ehrlich scavenging spectrophotometric assay of various concentrations of HA2PNA and its complexes.

Table (1): Analytical and Physical Data of HA2PNA and its Metal Complexes.


Empirical formula


M.P. o C




Pale orange








Dark green





chare at 260










Pale Yellow Pale Yellow Green

270 235 chare at 210

% Found. (Calc) C 71.38 (71.46) 50.04 (50.34) 47.53 (47.05) 47.48 (47.03) 49.18 (49.26) 43.64 (43.83) 38.34 (38.62) 50.56 (50.29)

H 5.42 (5.37) 3.28 (3.56) 4.72 (4.36) 4.69 (4.36) 4.27 (4.13) 3.46 (3.68) 2.73 (2.90) 3.92 (3.78)

Λam in DMSO








26.72 (26.25) 12.21 (12.10) 12.70 (12.14) 12.02 (11.86) 21.45 (21.59) 34.25 (33.95) 13.76 (14.00)

14.85 (14.62) 15.25 (14.61) 15.53 (15.31) 13.18 (13.62) 11.91 (12.00) 15.43 (15.62)

53 38 48 38 2 29

Λam in ohm-1 cm2 mol-1

Table (2): Most Important IR Spectral Bands of HA2PNA and its Metal Complexes.

Compound HA2PNA [Co(HA2PNA)Cl2(H2O)2] [Ni(HA2PNA)Cl2(H2O)2] [Hg(HA2PNA)Cl2] [Cu(HA2PNA)Cl2] [Cd(HA2PNA)Cl2(H2O)] [Mn(HA2PNA)Cl2(H2O)] [UO2(A2PNA)2]

ν(NH) 3201 3199 3173 3173 3190 3171 3137 -



1695 1658 1660 1685 1713 1684 1671 -

1626 1595 1592 1630 1635 1634 1634 -

ν(C=N)py ν(N-N) 1581 1578 1579 1583 1597 1589 1591 1617

1153 1158 1166 1160 1172 1164 1163 1150

Pyridine ring ν(M-O) breathing mode 950 958 490 960 490 954 490 955 963 499 962 499 958 489

ν(M-N) 420 424 427 420 420 420 424

Table (3): Magnetic Moments, Electronic Bands and Ligand Field Parameters of Metal Complexes of HA2PNA.


HA2PNA [Co(HA2PNA)Cl2(H2O)2] [Ni(HA2PNA)Cl2(H2O)2] [Cu(HA2PNA)Cl2] [UO2(A2PNA)2] [Mn(HA2PNA)Cl2(H2O)]

Band position (cm-1) 36231 33783 29412 14492 17241 14577 23809 17241 26315 21097 25641 20833 22222

Assignment transition

Ligand field parameters Dq (cm-1) B (cm-1) 

μeff (B.M.)

(π → π*)py (π → π*)C=N (n → π*)C=N





T1g → 4A2g 4 T1g → 4T1g(P) 3 A2g → 3T1g(F) 3 A2g → 3T1g(P) 2 B1g → 2A1g Cu → L CT 1 + Σ g → 2πu n → π* 6 A1g → 4T1g(G) 6 A1g → 4T2g(G)






















Table 4. Kinetic Parameters evaluated by Coats-Redfern equation for HA2PNA complexes. complex [Cd(HA2PNA)(H2O)Cl2] [Co(HA2PNA)(H2O)2Cl2]

[Cu(HA2PNA)Cl2] [Mn (HA2PNA)Cl2(H2O)]

peak 1st 2nd 1st 2nd 3rd 1st 2nd 1st 2nd 3rd 4th

Mid Temp(K) 584.31 889.03 579.77 734.94 961.84 531.03 923.77 534.23 756.53 914.64 1032.09

Ea KJ\mol 48.78 170.25 55.67 83.06 107.00 44.85 115.70 189.15 68.93 113.93 319.61

A (S-1) 2.05x105 6.41x 107 6.01x102 3.15x103 2.13x103 1.09x102 1.45 x104 2.76 x1016 1.44x102 1.21x104 1.38x1014

∆H* KJ\mol 43.92 162.86 50.85 76.95 99.01 40.43 108.02 184.70 62.64 106.33 311.04

∆S* KJ\mol.K -0.2063 -0.1045 -0.1972 -0.1854 -190.94 -0.2107 -0.1746 0.0650 -0.2113 -0.1760 0.01545

∆G* KJ\mol 164.44 255.80 165.20 213.24 282.66 152.31 269.33 149.99 222.52 267.35 295.090

Table5. Kinetic Parameters evaluated by Horowitz Metzger equation for HA2PNA complexes. complex


[Cd(HA2PNA)(H2O)Cl2] [Co(HA2PNA)(H2O)2Cl2]

[Cu(HA2PNA)Cl2] [Mn (HA2PNA)Cl2(H2O)]

1st 2nd 1st 2nd 3rd 1st 2nd 1st 2nd 3rd 4th

Mid Temp(K) 584.31 889.03 579.77 734.94 961.84 531.03 923.77 534.23 756.53 914.64 1032.09

Ea KJ\mol 58.96 185.48 65.63 95.47 122.45 54.18 131.68 197.77 81.80 129.40 337.02

A (S-1) 1.98x103 5.36x105 5.37x103 2.70x104 1.62x104 1.03x103 1.27 x105 1.98 x1017 1.29x103 1.04x105 1.10x1015

∆H* KJ\mol 54.10 178.08 60.81 89.36 114.45 49.77 124.00 193.33 75.51 121.80 328.439

∆S* KJ\mol.K -0.187 -0.086 -0.179 -0.167 -0.174 -0.192 -0.156 0.081 -0.193 -0.158 0.0327

Table 6: The antibacterial activity of HA2PNA and its metal complexes. Zone of inhibitionof bacterial growth (mm) Compound Bacillus Pseudomonas aeuroginosa (P.a.) thuringiensis(B.t.) (G-) (G+) 5 HA2PNA [Cu(HA2PNA)Cl2]






[Mn (A2PNA)Cl2(H2O)]



[Cd (A2PNA)Cl2 (H2O)]






Gentamicin* *: Standard drug.



∆G* KJ\mol 163.60 255.33 164.61 212.52 281.87 151.74 268.67 149.86 221.60 266.51 294.703

Table 7: Antioxidant and Erythrocyte hemolysis assay for the prepared ligand and its metal complexes. Compound DPPH Erythrocyte hemolysis (%) IC50(µg/ml) Control L-ascorbic acid 5.61 62.08 Dist.H2O(B) 100 HA2PNA 25.11 6.25 [Cu(HA2PNA)Cl2 7.89 68.84 [Ni(HA2PNA)Cl2(H2O)2] 7.93 93.27 [Mn (A2PNA)Cl2(H2O)] 11.55 63.31 [Cd (A2PNA)Cl2 (H2O)] 26.34 20.70 [Co(HA2PNA)(H2O)2Cl2] 7.97 40.99 [Hg(HA2PNA)Cl2] 62.25 50.00 [UO2(A2PNA)2] 10.86 72.00

Table 8:Ehrlich scavenging spectrophotometric assay of various concentrations and Ehrlich in vitro scavenging capacities (IC50) of HA2PNA and its complexes. Compound

Ehrlich inhibition (%) IC50(µg/ml) Concentration



100 ppm











[Mn (A2PNA)Cl2(H2O)]



































Molecular structure of [Cu(HA2PNA)Cl2]H2O complex


Highlights •

Preparation of Mn2+, Co 2+,Ni2+ , Cu2+, Cd 2+, Hg and U(VI)O22+ complexes of the new hydrazine Schiff base.

Elemental analysis, spectral characterization of the ligand and its complexes.

Thermal behavior of some solid metal complexes was studied using TGA technique.

The compounds were screened for antibacterial,antioxidant activity and cytotoxicity.


Synthesis, characterization and biological activity of 2-acetylpyridine-α naphthoxyacetylhydrazone and its metal complexes [corrected].

A new series of complexes of Ni(II), Co(II), Cu(II), Cd(II), Mn(II), Hg(II) and UO2(2+) derived from 2-acetylpyridine-α-naphthoxyacetylhydrazone (HA2P...
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