Accepted Manuscript Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[ N4 ] macrocyclic ligand Sunil G. Shankarwar, Bhagwat B. Nagolkar, Vinod A. Shelke, Trimbak K. Chondhekar PII: DOI: Reference:

S1386-1425(15)00158-4 http://dx.doi.org/10.1016/j.saa.2015.02.006 SAA 13296

To appear in:

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Received Date: Revised Date: Accepted Date:

27 June 2014 1 February 2015 3 February 2015

Please cite this article as: S.G. Shankarwar, B.B. Nagolkar, V.A. Shelke, T.K. Chondhekar, Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[ N4 ] macrocyclic ligand, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015), doi: http://dx.doi.org/10.1016/j.saa. 2015.02.006

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Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[ N4 ] macrocyclic ligand. Sunil G. Shankarwar, Bhagwat B. Nagolkar, Vinod A. Shelke, Trimbak K. Chondhekar* Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004, Maharashtra, India E-mail: [email protected] Abstract: A series of metal complexes of Mn(II), Co(II), Ni(II), Cu(II), have been synthesized with newly synthesized biologically active macrocyclic ligand. The ligand was

synthesized

by

condensation

of

β-diketone

1-(4-chlorophenyl)-3-(2-

hydroxyphenyl)propane-1,3-dione and o-phenylene diamine. All the complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV-Vis spectroscopy and mass spectroscopy. From the analytical data, stoichiometry of the complexes was found to be 1:2 (metal: ligand). Thermal behavior (TG/DTA) and kinetic parameters suggest more ordered activated state in complex formation. All the complexes are of high spin type and six coordinated. On the basis of IR, electronic spectral studies and magnetic behavior, an octahedral geometry has been assigned to these complexes. The antibacterial and antifungal activities of the ligand and its metal complexes, has been screened in vitro against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma respectively.

Keywords: macrocyclic ligand, transition metal complexes, thermal analysis, powder Xray diffraction. biological activity. Introduction Macrocyclic ligands and their metal complexes have a wide range of biological activities [1]. Transition metal complexes containing macrocycles are of considerable interest in terms of structural and coordination chemistry. The study of metal complexes of macrocyclic ligands appears to be interesting in view of the possibility of obtaining coordination compounds of unusual structure and stability. Transition metal macrocyclic complexes have received special attention because of their active part in metalloenzymes and as biomemitic model compounds due to their resemblance to natural proteins and enzymes. Synthetic tetraaza macrocycle (N4) molecules are considered typically good models for oxygen carriers due to the presence of four nitrogen donor sites confined to a single four-fold or a slightly fourfold plane in a ring structure, appropriate for metal ligand binding. A survey of the tetraaza macrocyclic ligand systems reported so far by earlier workers indicates that the ring size of 12–16 is most common for molecular model studies [2,3]. Aza-type ligands appear very promising for potential use as antifertile, antifungal and antibacterial agents as well as due to their other biological properties [4-7]. The formation of macrocyclic complexes depends on the size of the macrocycles, nature of its donor atoms and on the complexing behavior of the anions involved in coordination [8-10]. There is a continues interest in synthesizing macrocyclic complexes because of their potential applications in fundamental and applied sciences and importance in the area of coordination chemistry [11-14]. In view of the above applications, in the present paper we report the synthesis, characterization and antimicrobial studies of Mn(II),

Co(II), Ni(II), and cu(II) complexes with orthophenyl diamine containing nitrogen donor [N4] macrocyclic ligand having 14-membered backbone. Experimental All chemicals used were of the analytical grade (AR) and of highest purity. 4chlorobenzoic acid, ortho-hydroxy acetophenone and o-phenylenediamine were used for synthesis of ligand. AR grade metal chlorides were used for complex preparation. Spectroscopic grade solvents were used for spectral measurements. The carbon, hydrogen and nitrogen contents were determined on Perkin Elmer (2400) CHNS analyzer. IR spectra in the range of 4000-400 cm-1 were recorded on Jasco FT-IR-4100 spectrometer using KBr pellets. 1H-NMR spectra of the ligand was recorded in DMSO using TMS as an internal standard. The TG/DTA analysis was recorded on Perkin Elmer TA/SDT-2960 and XRD were recorded on Perkin Elmer employing CuKα radiation λ= 1.541A0 in the rang 10-800. The UV-Vis spectra of the complexes were recorded on ShimadzuUV-1800 Spectrophotometer. Magnetic susceptibility measurements of the metal complexes were done on a Gouy balance at room temperature using Hg.[Co(SCN)4] as calibrant. Molar conductance of complexes was measured on Elico CM-180 conductometer using 1 mM solution in dimethyl sulphoxide. synthesis of β-Diketone Step I Equimolar amount of 4-chloro benzoic acid and ortho-hydroxy acetophenone were dissolved in 50 mL dry pyridine. The reaction mixture was then cooled to 0°C. To this, phosphorus oxychloride (0.06 mol) was added drop wise maintaining temperature below 10°C. The reaction mixture was kept overnight at room temperature. It was then poured on crushed ice with vigorous stirring. The crimson colored solid (ester) was

obtained which was filtered and washed several times with ice-cold water. Ester was then crystallized with distilled ethanol. Purity of the compound was checked by TLC. Ester was subjected to well known Baker-Venkatraman transformation. Ester (0.03 mol) was dissolved in 15 mL dry pyridine. To this mixture, powdered KOH (1gm) was added and the reaction mixture was stirred on magnetic stirrer at room temperature for 5 hours. Then it was poured over crushed ice and acidified with concentrated hydrochloric acid. Finally yellow colored product was obtained which was recrystallized from ethanol (Yield 5558%). Purity of all synthesized β-diketones were checked by TLC using silica gel G and melting points.

Scheme1. synthesis of β-Diketone Step II synthesis of macrocyclic ligand A hot ethanolic solution, 25 ml of orthophenylene diamine

0.02M and an

ethanolic solution 25 ml of β-Diketone 0.02M were mixed slowly under constant stirring. The resulting solution was refluxed for six hours in presence of 2-3 drops of concentrated HCl. On cooling, light yellowish crystals separated out were filtered, washed with ethanol and dried under vacuum.

Scheme 2. synthesis of macrocyclic ligand. synthesis of metal complexes A hot ethanolic solution, 25 ml of ligand (0.002M) and a hot ethanolic solution , 25 ml of required metal salt (0.001M) were mixed together under constant stirring. The mixture was refluxed for 8-9 hours. On cooling, a coloured solid precipitate formed was filtered, washed with cold ethanol, chloroform and dried under vacuum (fig 1).

Where M = Mn (II), Co (II), Ni (II), Cu (II)

Fig.1 Structure of Metal Complexes. Results and Discussion All the complexes were colored solids, air stable and soluble in polar solvents like DMF and DMSO. The elemental analysis show 1:2 (metal: ligand) stoichiometry for all the complexes. Micro analytical data and molar conductance values are given in (Table 1). The metal contents in complexes were estimated by gravimetric analysis [15]. All the complexes show low conductance which indicates their non-electrolytic nature. The magnetic measurement studies show that the Mn(II), Co(II), and Cu(II), complexes exhibit paramagnetic whereas the Ni(II) shows diamagnetic behavior (Table 1). 1

H-NMR spectra of ligand The 1H NMR spectra of the ligand was recorded in DMSO. It shows following

signals at 2.55, (s,4H -CH2), 8.55  (s,2H,-OH),6.9-8.5 corresponding to phenyl ring protons (m,24H). Mass Spectra of the ligand Mass spectral data confirmed the structure of ligand HL as indicated by the peaks corresponding to their molecular mass. FTIR spectra The IR spectra of ligands (Table 2) do not show any band at 1700 cm-1 (υ C=O) 3380 cm-1 (υas NH2) and 3250 cm-1 (υs NH2) corresponding to carbonyl groups and free amine[16]. There are two main features in the infrared spectrum of the macrocyclic ligand. The first feature is the disappearance of the two characteristic between the

primary amine group –NH2 of the diamine and >C=O of the diketone. It also confirmed the elimination of a water molecule and complete condensation[17]. A band corresponding to the (υ C=N) (azomethine linkage) appers at 1641-1658 cm-1 in the spectra. The structure suggested to the ligand is shown in (scheme 2). The position of this band is shifted to lower frequency in the complexes as compared to free macrocyclic ligand suggesting that the coordination takes place through the nitrogen of (υ C=N) group [18]. Electronic absorption spectra and magnetic measurements Electronic spectra of Mn(II) complex in DMSO solution, display four weak intensity absorption bands (Table 3) in the range of 18,100–18,587 cm-1, 23,200–24,570 cm-1, 27,000–29,412 cm-1 and 30,950–33,003 cm-1. These bands may be assigned to the transitions, 6A1g→ 4T1g (4G), 6A1g →4Eg, 4A1g (4G), 6A1g → 4Eg (4D) and 6A1g → 4T1g (4P), respectively. The magnetic moment recorded at room temperature was 5.86 B.M. corresponding to five unpaired electrons [19,01]. The Co(II) complex shows three bands at 12,360-12,509 cm-1, 16,051-17,123 cm1

and 22,026-22,229 cm-1 corresponding to the transitions 4T1g(F) → 4T2g (F), 4T1g → 4A2g

and 4T1g(F) → T2g (P) respectively. These electronic tranisitions and observed magnetic moment of 4.8 B.M. indicated high spin octahedral geometry [20]. The electronic spectra of Ni(II) complex exhibited three bands in the 13,333– 14,390, 18,587–18,621, and 26,385–27,700 cm-1 regions corresponding to 3A2g(F) → 3T2g (F), 3A2g (F)→ 3Tg (F), and 3A2g (F)→ 3T1g (P) transitions respectively. The observed magnetic moment of Ni(II) complex at room temperature was 2.95 BM. These values are

in tune with a high spin configuration and show the presence of an octahedral environment around Ni(II) [21]. The electronic spectra of Cu(II) complex exhibits three bands in the 10,02010,143 cm-1, 14,684-14,788 cm-1, and 22,075-23,154 cm-1 regions. These bands may be assigned to the transitions 4T1g(F) → 4T2g (F), 4T1g (F) → 4A2g(F) and 4T1g(F) → T1g (P) respectively. The positions of bands indicated that the Cu(II) complex have an overall octahedral geometry. Electronic spectral data coupled with observed maganetic moment of 1.94 B. M. further supports the octahedral geometry [22]. On the basis of analytical and spectral data, octahedral structures have been proposed for all the complexes (Table 3). Thermal analysis. The simultaneous TG/DT analysis of some representative metal complexes was done from ambient temperature to 1000 ºC in nitrogen atmosphere using α-Al2O3 as reference. In the thermogram curve of Mn(II) complex, the first step shows a steep slope between 140–230 °C with a mass loss of 5.65 %(calculated 5.89%), indicating the removal of two molecules of coordinated water[18, 19]. An endothermic peak in the range 140–200 °C (ΔTmax = 195°C) on DTA curve corresponds to dehydration step. The anhydrous complex then shows slow decomposition from 200-300°C in first step with 15.00% (calcd. 14.10%) mass loss and a broad exotherm (ΔTmax = 252°C) in DTA which may be attributed to removal of noncoordinated part of the ligand. The second step decomposition is from 400 to 600°C with 11.70% (calcd 12.09%) mass loss corresponding to decomposition of coordinated part of ligand. A broad endotherm in DTA is observed for this step. The mass of final residue 28.04% corresponds to stable

MnO. The thermogram of Co(II) complex shows in first step a steep slope between 140–230 °C with a mass loss of 6.35 %(calculated 6.89%) indicating the removal of two molecules of coordinated water. An endothermic peak in the range 140–230 °C (ΔTmax = 225°C) on the DTA curve corresponds to dehydration step. The anhydrous complex then show slow decomposition from 200-300°C, with 10.00% (calcd. 11.92%) mass loss and a broad exotherm (ΔTmax = 245°C) in DTA may be attributed to removal of noncoordinated part of the ligand. The second step decomposition from 400 to 600°C with 18.00% (calcd 17.09%) mass loss corresponds to decomposition of coordinated part of ligand. A broad endotherm in DTA is observed for this. The mass of final residue 34.01 % corresponds to stable CoO. Powder X-ray diffraction analysis The X-ray powder diffractogram of the metal complexes (fig 2) were used for the structural characterisation and determination of lattice dimensions. The observed data of complexes under investigation was compared with other literature data having analogous cell and subsequently indexed to similar geometry. The X-ray diffractogram of metal complexes was scanned in the range 20–80 at wavelength 1.540A˚. The diffractogram and associated data depict 2θ values for each peak, relative intensity and interplanar spacing (d-values). The X-ray diffraction pattern of these complexes with respect to major peaks having relative intensity greater than 10% have been indexed by using computer programme[10]. The diffractogram of Mn(II) complex shows 27 reflections with maxima at 2θ =70.660 corresponding to d value 1.33A. The observed values of lattice constants, a= 8.67A˚, b = 8.56A˚, c = 9.99A˚ and α =β =γ = 90o. Mn(II) complex satisfies the condition a≠ b≠c and α =β =γ = 90o required for the compound to be

orthorhombic lattice type. The diffractogram of Co(II) complex shows 21 reflections with maxima at 2θ =18.124 corresponding to d value 4.89A˚. The values of lattice constants, a= 9.55A˚, b = 9.55A˚, c = 10.23A˚ and α =β =γ = 90o. These values satisfy the condition a=b≠ c and α =β =γ = 90o required for the compound to be tetragonal lattice type. The diffractogram of Ni(II) complex shows 19 reflections with maxima at 2θ =43.726 corresponding to d value 2.06A˚ and observed values of lattice constants, a= 5.46A˚, b = 5.46A˚, c = 6.33A˚ and α =β =γ = 90o satisfy the condition a= b≠c and α =β =γ = 90o required for the compound to be tetragonal lattice type. The diffractogram of Cu(II) complex shows 26 reflections with maxima at 2θ =23.075 corresponding to d value 3.85A˚ and observed values of lattice constants, a= 6.46A˚, b = 7.21A˚, c = 6.32A˚ and α =β =γ = 90o satisfy the condition a≠ b≠c and α =β =γ = 90o required for the compound to be orthorhombic lattice type.

Fig. 2. X-ray diffractograms of Mn (II), Co (II), Ni (II), and Cu (II) complexes. Kinetic calculations The kinetic and thermodynamic parameters viz order of reaction (n), energy of activation (Ea), pre-exponential factor (z), entropy of activation (ΔS) and free energy change (ΔG) together with correlation coefficient (r) for non-isothermal decomposition of metal complexes have been determined by Horowitz-Metzer (HM) approximation method and Coats-Redfern integral method [29,24].

Horowitz-Metzer (HM) approximation method  1  (1   )1n log   (1  n)

 Ea ZRTs 2 E   log   2 E 2.303RTs 2  2.303RTs

Where α = Fraction decomposed.

 = heating rate (10oC/min.)

n = order of reaction.

R = Molar gas constant.

Ts = Temperature at half wt. loss.

k = Boltzman constant.

Z = Frequency factor.

h = Plank’s constant.

The equation used for calculating entropy change (ΔS) is given below. S  2.303R log

Zh k Ts

Where, k - Boltzman constant, h- Planck’s constant, β – Rate of heating 100C/min., RMolar gas constant and Ts -Peak temperature. Coats Redfern Method The thermodynamic activation parameters of decomposition processes of complexes were calculated by this method. The activation energy (Ea), enthalpy (∆H*), entropy (∆S) and Gibbs free energy change of the decomposition (∆G*) were evaluated by employing the Coats –Redfern relation

log[

log{W f / W f  W } T

2

ZR 2 RT E* (1  )]  E* E* 2.303RT

 log[

Where Wf -is the mass loss at the completion of the reaction. W is the mass loss up to temperature T R- Gas constant E*- Activation energy in KJ/mol -is the heating rate

(1-(2RT/E*)  1 A plot of L.H.S. of equation against 1/T gave a slope from which E* was calculated H *  E *  RT

S *  2.303R[(log

Zh )] KT

G*  H * T S * The data is given in (Table 4). The results show that the values obtained by two methods are comparable. The calculated values of energy of activation of Mn(II), Co(II), Ni(II) and Cu(II) complexes are relatively low indicating the autocatalytic effect of metal ions on the thermal decomposition of metal complexes [24-25]. The negative values of entropy of activation indicates that the activated complex is more ordered than the reactant and that the reaction is slow. The more ordered nature may be due to the polarization of bonds in activated state which might happen through charge transfer electronic transitions. Antimicrobial activity The antibacterial activities of ligand and its metal complexes were tested in vitro against bacteria such as Staphylococcus aureus and Escherichia coli by paper disc plate method [26]. The compounds were tested at the concentration 250 and 500 µg cm-3 in DMSO and compared with known antibiotics viz Rifampicin (Table 5). For fungicidal activity, compounds were screened in vitro against Aspergillus niger and Trichoderma by mycelia dry weight method [27] with glucose nitrate media. The compounds were tested at the concentration 250and 500 µg cm-3 in DMSO and compared with control (Table 6). From Table 5 and 6, it is clear that the inhibition by metal chelates is higher than that of their parent ligand and metal salts. The results are in good agreement with previous

findings with respect to comparative activity of free ligand and its complexes [26-27]. The metal chelates have higher antibacterial activity than the corresponding free ligand and control against the same microorganism under identical experimental conditions.This increased activity of metal chelates can be explained on the basis of chelation theory [26]. Such enhanced activity of metal chelates is due to increased lipophilic nature of the metal ions in complexes [27]. Transport of both, metal and ligand across lypophilic membranes to vital intramolecular sites is favoured by chelation. Once intracellular, the fully coordinated complex or one of its derivatives, including the dissociated metal or ligand may be the active entity.The increase in activity with concentration is due to the effect of metal ions on the normal process. The microbial results are presented in (Tables 5 and 6). In case of antibacterial studies it was observed that, the ligand is moderately active towards Stapylococcus and less active to E. coli. However, all the metal complexes show enhanced antibacterial activity against both bacterial species. The ligand and its metal complexes show fungal growth inhibition in the following order: Co(II) > Ni(II) > Cu(II) > Mn(II) > HL. The antibacterial capacity of the ligand and its metal complexes show following order: Ni(II) > Co(II) > Mn(II) > Cu(II) > HL. Conclusion Metal complexes of Mn(II), Co(II), Ni(II), and Cu(II) with novel macrocyclic ligand were synthesized. The structure of macrocylic ligand have been proposed on the basis of IR, 1H NMR mass spectra which acts as a tetradentate ligand by coordinating through four azomethine nitrogens. The elemental analysis, magnetic measurements, IR and electronic spectra revealed the formation of monomeric complexes. Octahedral

structures were assigned to these complexes on the basis of elemental and spectral data. Presence of two coordinated water molecules was proved by TG/DTA, analysis x-ray diffraction study showed that the Mn(II), Cu(II) complexes have orthorhombic and Co(II), Ni(II) complexes have tetragonal crystal structures. All these complexes were found to have enhanced antibacterial and antifungal activities than the parent ligand. ACKNOWLEDGEMENT One of the Authors (T. K. Chondhekar) is thankful to UGC, New Delhi for awarding UGC-BSR Faculty Fellowship. Thanks are also due to CSIR New Delhi for financial support. References 1) S. Chandra, A. Gautam, J. Serb. Chem. Soc. 74(12) (2009) 1413. 2) G.A. Melson, Coordination Chemistry of Macrocyclic Compounds, Plenum Press, New York, 1979. 3) B.J. Hathaway, D.E. Billing, Coord. Chem. Rev. 5 (1970) 143. 4) D. P. Sing, R. Kumar, V. Malik, P. Tagi, J. Enzyme Inhibmed. Chem. 22 (2007) 177. 5) Z. H. A. EI-Waheb, J. Coord. chem. 43 (2009) 231. 6) S. Chandra, M. Tyagi, S. Agrawal, J. Serb. Chem. Soc. 75 (7) (2010) 935-941. 7) T. M. hunter, S. J. Paisey, H. S. Park, J. Inorg. Biochem. 98 (2004)713. 8) R.R. Gange, C.I. Spiro, T.J. Smith, W.R. Hamann, W.R. Thies, K. Shiemke, J. Am. Chem. Soc. 103 (1981) 4073. 9) G. Cross, J.P. Costs, Acad. C. R. S. C. Paris 294 (1982) 173. 10) S. Ilhan, H. Temel, I. Yilmaz, M. Sekerci, Polyhedron 26 (12) (2007) 2795.

11) V. Dier, J. V. Cuevas, G. G. Herbosa, G. Aullon, J. P. H. Charwant A. Carbayo, A. Munoz, Inorg. Chem. 46 (2007) 568-577. 12) M. Salavati-Naissari, M. R. Adaryni, S. Heydarzadeh, Transition Met. Chem. 30 (2005) 445. 13) P. Sangputa, R. Dinda, S. Ghosh, W. S. Sheldrick, Polyhedron 22 (2003) 477. 14) L. Leelavathy, S. Anbu, M. Kandaswamy, N. Karthikeyan, N. Mohan Polyhedron 28 (2009) 903–910. 15) A.I. Vogel, A Text Book of Quantitative Inorganic Analysis, third ed., Longmans, London. 1975 PP 540. 16) K. Nakamoto, Infrared Spectra of Inorganic and Coordination Spectroscopy, first ed. Elsevier, Amsterdam, 1968. 17) S. Chandra, K. Gupta, Transition Met. Chem. 27 (2002) 32 18) S. Chandra, R. Kumar, Spectrochemica. Acta part A 61 (2005) 437-446. 19) H.H. Horowitz, G. Metzger, Anal. Chem, 35 (1963) 1464. 20) S. Chandra, A. Gautam, M. Tyagi J. Trans Met chem. 32 (2007) 1079-1084. 21) U. Kumar, S. Chandra J. Saudi chem Society 15 (2011) 187-193. 22) V. K. Revankar, V. B. Mahale; Indian J. Chem.A, 28 (1979) 683. 23) A.W. Coats, J.P. Redferm, Nature 201 (1964) 68. 24) A. M. El-Awad, J. Therm. Anal. Cal, 61 (2000) 197. 25) A. Impura, Y. Inoue, I. Yasumori, Bull. Chem. Soc. Jpn, 56 (1983) 2203. 26) K. Mohanan, S. N. Devi, Russian J. Coord Chem 32(8) (2006) 600. 27) P.S. Mane, S.G. Shirodkar, B.R. Arbad, T. K. Chondhekar, Indian J. Chem 40 (2001) 648.

28) R.P. Venketeswar, N.A. Venkta, Indian J. Chem. 42 (2003) 896. 29) L. Mishra, V.K. Singh, Indian. J. Chem. 32 (1993) 446.

Figure Captions: Scheme 1. Synthesis of β-Diketone

Scheme 2. Synthesis of macrocyclic ligand.

Fig.1 Synthesis of Metal Complexes.

Where M = Mn (II), Co (II), Ni (II), Cu (II)

Fig. 2. X-ray diffractograms of Mn (II), Co (II), Ni (II), and Cu (II) complexes.

Table .1. Physical characterization, analytical and molar conductance data of ligand and its metal complexes.

Ligand/Complexes

F. W.

M.P. /

Magnetic

Molar

% Found

Decomp.

moment

conduc.

(Calculated)

Temp. 0

(HL)

[MnL(H2O)2 ]

[CoL(H2O)2 ]

[NiL (H2O)2 ]

[CuL (H2O)2]

693.631

784.569

752.564

752.321

757.177

C

μeff (B.M.)

185 ----

>300

>300

>300

>300

5.86

4.81

2.95

1.94

Mho 2

cm mol

C

H

N

M

72.12

4.88

7.50

(72.72)

(4.35)

(8.07)

_

64.60

4.07

6.80

7.40

(64.29)

(4.36)

(7.14)

(8.15)

66.81

4.10

7.10

8.05

(67.03)

(4.55)

(7.44)

(8.50)

67.10

4.09

7.60

7.70

(67.05)

(4.55)

(7.44)

(7.80)

66.95

4.84

7.20

8.50

(66.62)

(4.52)

(7.39)

(8.45)

-1

----

28.00

27.04

12.06

23.04

Table.2 FTIR Spectra of the ligand (HL) and its macrocyclic metal complexes (cm-1). Ligand/Complexes (OH)

(C=N)

(C-N)

(C-Cl)

(C-O)

(M-N)

HL

3664

1658

1055

754

1219

[MnL(H2O)2 ]

3695

1645

1066

742

1259

455

[CoL(H2O)2 ]

3736

1600

1091

742

1245

465

[NiL(H2O)2 ]

3680

1604

1014

750

1257

449

[CuL(H2O)2 ]

3712

1602

1064

740

1250

473

Table 3. Magnetic and Electronic absorption spectral data of compounds. Frequency in cm-1 Compound

[MnL(H2O)2 ]

[CoL(H2O)2 ]

[NiL(H2O)2 ]

Band Assignment

Geometry

18,100-18587

6

A1g→ 4T1g

Octahedral

23,200-24,570

6

A1g →4Eg, 4A1g

27,000-29,412

6

A1g → 4Eg

30,950-33,003

6

A1g → 4T1g

12360-12509

4

T1g(F) → 4T2g (F),

16051-17123

4

T1g → 4A2g

22026-22229

4

T1g(F) → T2g (P),

13333–14390

3

A2g(F) → 3T2g (F),

3

A2g (F)→ 3Tg (F),

18587–18621

3

26385–27700 10020-10143 [CuL(H2O)2 ]

14684-14788 22075-23154

4

4

Octahedral

A2g (F)→ 3T1g (P),

T1g(F) → 4T2g (F),

4

Octahedral

T1g (F) → 4A2g(F)

T1g(F) → T1g (P),

Octahedral

Table 4. The kinetic parameters of metal complexes calculated by Horowitz-Metzger (HM) and Coats-Redfern (CM) methods. Corelation Complex

Step

n

Ea

A

ΔS#

ΔG#

(kJmol-1)

(S-1)

JK-1mol-1

(kJmol-1)

Method

coefficient (r)

I

HM

4.47

2.84×103

-172.50

18.63

0.9994

CR

24.18

11.353

-175.90

18.66

0.9975

HM

14.75

8.37×10-2

-170.76

38.01

0.9998

CR

8.97

3.30

-159.689

36.51

0.9969

HM

7.31

0.11

-173.68

20.22

0.9919

CR

19.78

32.86

-161.87

19.34

0.9975

HM

29.11

0.605

-160.45

52.90

0.9938

CR

23.53

1.43

-142.57

50.25

0.9979

HM

2.94

1.77×102

-179.62

16.22

0.9948

CR

16.62

5.376

-178.51

16.14

0.9915

HM

29.11

0.6054

-156.097

52.38

0.9985

CR

20.37

2.41

-142.698

50.25

0.9967

HM

7.31

0.118

-174.71

20.29

0.9919

CR

10.8

1.168

-161.87

19.34

0.9998

HM

23.29

6.251

-166.74

47.94

0.9997

CR

13.57

7.900

-149.86

45.51

0.9953

0.45

Mn(II) II

I

0.45

0.45

Co(II) II

I

0.45

0.46

Ni(II) II

I

0.46

0.40

Cu(II) II

0.40

Table 5. Antibacterial activity of HL and its metal complexes. inhibition Zone diameter (mm) E.coli

Staphylococcus aures

Ligand/Complexes

250ppm

500ppm

250ppm

500ppm

Rifampicin

40

40

42

42

(HL)

08

11

12

14

[MnL(H2O)2 ]

14

26

11

19

[CoL(H2O)2 ]

15

16

17

20

[NiL(H2O)2 ]

16

21

31

28

[CuL(H2O)2 ]

12

22

14

17

Table 6. Antifungal activity of compounds yield of mycelia dry weight in mg (% inhibition) Aspergillus niger

Trichoderma

Ligand/Complexes

250ppm

500ppm

250ppm

500ppm

Control

40

40

40

40

(HL)

14(65)

11(72)

13(68)

10(75)

[MnL(H2O)2 ]

11(72)

09(78)

14(65)

07(83)

[CoL(H2O)2]

30(25)

11(73)

17(58)

09(78)

[NiL(H2O)2 ]

27(33)

10(75)

12(70)

10(75)

[CuL(H2O)2]

25(38)

04(90)

19(53)

11(73)

Graphical Abstract


Metal complexes of Mn(II), Co(II), Ni(II), Cu(II),
Synthesized by condensation of β-diketone
All the synthesized compound Characterized by spectroscopy techniques.
The complexes was found to be 1:2 (metal: ligand).
The antibacterial and antifungal activities of the ligand and its metal complexes.