Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand

Article abstract of DOI:10.1016/j.molstruc.2015.09.030

A new tridentate acyclic pincer ligand, [bi(pyridin-2-methyl)amine] (bpma, HL), was synthesized and reacted to form complexes with copper(II), nickel(II), iron(II), cobalt(II) and zinc(II) ions. Both the ligand and its complexes were characterized using elemental analysis, molar conductance, infrared, ¹H-NMR-spectroscopy, mass and thermal analyses. According to the spectroscopic data, all of the complexes share the same coordination environment around the metal atoms, consisting two nitrogen-pyridine entities, one nitrogen-methylamine entity, one/two water molecules and/or one/two chloride or bromide ions. Complexes also showed molar conductivity according to the presence of two halide anions outer the coordination sphere except Co(II) and Zn(II) complexes are non electrolytes. Analysis indicates that the metal ions have trigonal bipyramidal structure. Cu(II), Ni(II), Fe(II), Co(II), and Zn(II) metal complexes were screened for their antibacterial activity against Bacillus subtilis, Staphylococcus aureus (G+) and Escherichia coli, and Pseudomonas aeruginosa (G-) bacteria. They showed remarkable antimicrobial activity.

Full text of DOI:10.1016/j.molstruc.2015.09.030

Accepted Manuscript
Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate
coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand
Hanan F. Abd El-Halim, Gehad G. Mohamed
PII:
S0022-2860(15)30293-3
10.1016/j.molstruc.2015.09.030
MOLSTR 21836
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 22 June 2015
Revised Date: 10 September 2015
Accepted Date: 29 September 2015
Please cite this article as: H.F. Abd El-Halim, G.G. Mohamed, Synthesis, spectroscopic studies,
thermal analyses, biological activity of tridentate coordinated transition metal complexes of bi(pyridyl-2-
ylmethyl)amine]ligand, Journal of Molecular Structure (2015), doi: 10.1016/j.molstruc.2015.09.030.
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ACCEPTED MANUSCRIPT
N
N
OH2
OH2
OH2
Cl
HN
Cu
Cl .H O
HN
Cl.H O
2
2
2
Ni
N
N
N
X
N
OH2
Cl
HN
M
HN
Cl
X
Fe
N
N
M= Co, Zn; X= Cl, Br
Structure of the [bi (pyridin-2-methyl) amine] (bpma) metal complexes.

ACCEPTED MANUSCRIPT
Synthesis, spectroscopic studies, thermal analyses, biological activity of tridentate
coordinated transition metal complexes of bi(pyridyl-2-ylmethyl)amine]ligand
a
b
Hanan F. Abd El-Halim *, Gehad G. Mohamed
a*
Pharmaceutical Chemistry Department, Faculty of Pharmacy, Misr International University,
Heliopolis, Cairo, Egypt. e-mail:Hanan.Farouk2@yahoo.com.
1
b
Chemistry Department, Faculty of Science, Cairo University, 12613 Giza, Egypt.
Abstract
A new tridentate acyclic pincer ligand, [bi(pyridin-2-methyl)amine] (bpma, HL), was
synthesized and reacted to form several complexes with copper(II), nickel(II), iron(II), cobalt(II)
and zinc(II) ions. Both the ligand and its coordination complexes were characterized using
1
elemental analysis, molar conductance, infrared, H-NMR-spectroscopy and thermal analyses.
According to the spectroscopic data, all of the complexes share the same coordination
environment around the metal atoms, consisting two nitrogen-pyridine entities, one nitrogen-
methylamine entity, one - two water molecules and/or one - two chloride or bromide ions.
Complexes also showed molar conductivity according to the presence of two halide anions outer
the coordination sphere except Co(II) and Zn(II) complexes are non electrolytes. Analysis
indicates that the metal ions have trigonal bipyramidal structure. Cu(II), Ni(II), Fe(II), Co(II),
and Zn(II) metal complexes were screened for their antibacterial activity against Bacillus
subtilis, Staphylococcus aureus (G+) and Escherichia Coli, and Pseudomonas aeruginosa (G-)
bacteria. They showed remarkable antimicrobial activity.
Keywords: bi(pyridyl-2-ylmethyl)amine]- Metal complexes- Spectroscopy -Biological activity.
1
. Introduction
Catalytic activity of transition metal complexes that are coordinatively unsaturated may
play an important role in catalytic processes [1]. Such compounds also find applications in
degrading environmental pollutants as they act as biomimetic catalysts [2]. Que et al. reported
the catalytic activity of a terapyridyl iron complex, the Fe(II)[N,N-bis-(2-pyridylmethyl)-N-di(2-
pyridyl)methyl-amine] which is able to catalyze alkane oxidation with hydrogen peroxide [3].
Thus, the synthesis of new complexes is highly desirable. The synthesis of new receptors with
pendant arms that have aromatic or aliphatic units is a fascinating area of research because of the
importance of these receptors both in basic and applied chemistry. A subject of special interest is
1

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the design of homo- or hetero-binuclear complexes for biomedical applications that require
covalent attachment of the macrocycle system to a recognition site [4-9].
Special interest has been devoted to the design of new catalysts of late transition metal
complexes consisting of tridentate nitrogen-based ligands as non-metallocene olefin
polymerization catalysts [10-16]. These catalysts enhance both the activity and microstructure of
the resultant polymers as a pincer type ligand being thus capable of coordinate in a tridentate
manner. The facility to modify and tune the properties of these ligands and their complexes has
been reflected in their applications in different areas of chemistry, particularly in catalysis [17].
Reduction of the diisopropylarylbis(methylimino)pyridine iron dibromide, iPrPDIFeBr2
(iPrPDI = 2,6-(2,6-(CHMe )2C H N=CCH )2C H N)(1-Br ), yielded the corresponding bis
2 6 3 3 5 3 2
(
dinitrogen) compound, iPrPDIFe(N ) (1-(N ) ), which proved to be a thermally stable, highly
2
2
2 2
active pre-catalyst for hydrogenation and hydrosilation of olefins [18]. The stability and catalytic
activity of the complex has been attributed to the ligand’s capacity to accept up to three electrons
[
19] from the metal center through conjugated π-acidic nitrogen atoms to mitigate the one
electron redox changes intrinsic to iron [9].
Pyridine-containing macrocycles are interesting because of their versatility. They can be
used as building blocks that lead to more complicated structures, including systems with more
than one cavity, cages with three dimensional, and ligands having additional functional groups
attached to the macrocyclic skeleton [20–26]. Some macrocycles involving N-methyl-pyridine,
N-methyl-indole, or N-methyl-imidazole have been synthesized and their coordination ability
towards divalent and trivalent metal anions was studied [27–30]. The preparation of new
receptors with pendant arms that have aromatic or aliphatic units is an interesting area of
research because of the importance of these receptors in basic and applied chemistry. One of the
most interesting subjects is the design of homo- or hetero-binuclear complexes for biomedical
applications that require covalent attachment of the macrocycle system to a recognition site [31–
3
5]. Cytotoxic studies of transition metal ion concentrations have also been carried out using
macrocyclic ligands with pendant arms [36, 37]. Lanthanide (III) ions have also been employed
as effective template agents [38, 39] in the synthesis of large macrocycles with pyridine head
units.
In this work, bi(pyridin-2-methyl)amine ligand and its Cu(II), Ni(II), Fe(II), Co(II), and
Zn(II) metal complexes were prepared. The ligand and its new transition metal complexes were
2

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1
characterized by elemental analysis, IR, MS, H-NMR spectroscopy. Thermal stability and
biological activity were investigated for selected compounds.
2
2
. Experimental Section
.1. Materials and instruments.
The metal salts CuCl 2H O (Sigma), CoCl 3H O and NiCl 6H O (BDH); ZnBr 4H O
2
*
2
2*
2
2*
2
2*
2
(
Ubichem), and FeCl 2H O (Sigma)) were used as purchased. All of the complexes synthesized
2* 2
melted above 300 °C. The solvents were reagent grade.
Microanalyses of carbon, hydrogen and nitrogen were carried out at the Microanalytical Center,
Cairo University, Egypt, using CHNS-932 (LECO) Vario Elemental Analyzer. The molar
magnetic susceptibility was measured on powdered samples using the Faraday method. The
diamagnetic corrections were made by Pascal’s constant and Hg[Co(SCN) ] was used as a
4
−3
calibrant Molar conductivities of 10 M solutions of the solid complexes in DMF were
measured on the using Jenway 4010 conductivity meter. IR spectra were obtained on an FT-IR
Perkin-Elmer 1740 spectrophotometer (KBr pellets), covering the range between 400 and 4000
-1
1
cm . H-NMR spectra was recorded on a Bruker ARX-300 spectrometer (CDCl solutions,
3
tetramethylsilane was used as standard). The mass spectrum of the Ni(II) complex was recorded
by EI technique at 70 eV using MS-5988 GS–MS Hewlett-Packard instrument at the
Microanalytical Center, Cairo University. Thermogravimetric analyses (TG/DTG) were carried
out in the temperature range from 25 to 800 ºC in a steam of nitrogen atmosphere using
Shimadzu TG 50H thermal analysis. The experimental conditions were: platinum crucible,
nitrogen atmosphere with a 30 ml/min flow rate and a heating rate 10 ºC/min.
2
.2. Microbiological investigations
For these investigations the filter paper disc method was applied according to Gupta et al.
[
40]. The investigated isolates of bacteria were seeded in tubes with nutrient broth (NB). The
3
3
seeded NB (1 cm ) was homogenized in the tubes with 9 cm of melted (45 ºC) nutrient agar
(NA). The homogeneous suspensions were poured into Petri dishes. The discs of filter paper
(diameter 4 mm) were ranged on the cool medium. After cooling on the formed solid medium, 2
-5
3
×
10 dm of the investigated compounds were applied using a micropipette.
After incubation for 24 h in a thermostat at 25–27 ºC, the inhibition (sterile) zone
diameters were measured and expressed in mm. An inhibition zone diameter over 7 mm
indicates that the tested compound is active against the bacteria under investigation. The
3

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antibacterial activities of the investigated complexes were tested against four types of bacteria.
The organisms used in the present investigations included two Gram positive bacteria (Bacillus
subtillis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and
Pseudomonas aereuguinosa). Metal complexes were tested, as well as the standard. The
−
3
3
concentration of each solution was 2.0×10 mol dm .
.3. Synthesis of [bi (pyridin-2-methyl) amine] (bpma).
-pyridinecarboxaldehyde (13.90 mL, 145 mol) dissolved in 40 ml ethanol was added
2
2
dropwise to a solution of 2-(aminomethyl)pyridine (15.0 mL, 0.146 mol) in 150 ml ethanol. The
mixture was left stirring for 15 min. Sodium borohydride (14.0 g, 0.370 mol) was added and the
reaction was refluxed for 50 minutes. 15 ml of conc. HCl dissolved in 10 ml ethanol was added
dropwise to the mixture while cooling in an ice bath. The mixture was left for 30 minutes in the
ice bath and remained in the refrigerator overnight. A white precipitated was isolated by
filtration. Sodium hydroxide (24g, 0.6 mol) dissolved in 60 ml water was added to a dissolved
product (180 mL of water), a two-phase system was formed with the product on top. Diethyl
ether was added to extract the product. After removal of diethyl ether, the product was dissolved
in 250 ml ethanol and filtered [41]. The filtered solution was cooled in an ice bath and 65 ml of
conc. HCl was added, a white precipitate was formed then dried in vacuum. The resulting white
1
crystals (38.6g, 0.125 mol, 86% yield). H-NMR (Figure ): the signals found in the spectrum at δ
=
8.76 - 7.52 (m, 8H, pyridine-H), 4.38 (br, 4H, -CH ) and 3.72 (s, 1H, NH) can be assigned to
2
the aromatic, N-H and methylene protons, respectively. Anal. calcd for C H N : C, 72.36; H,
12
13
3
6
.53; N, 21.11, Found: C, 72.12; H, 6.83; N, 20.95.
Scheme1: Structure of bi(pyridin-2-ylmethyl)amine ligand.
4

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2
.4. Synthesis of [CuCl (bi(pyridin-2-ylmethyl)amine].
2
The complex was synthesized using CuCl .2H O (432 mg, 2.53 mmol). Blue precipitate
2
2
was obtained. Yield: 0.73g (78%). FT-IR: ν(H O),ν(NH), ν(C=N), ν(C=C) and ν(M-N) are
2
-1
3
420, 3070, disap., 1606, and 650 cm , respectively. Anal. calcd for
[
(C H N )Cu(H O) ]Cl .H O: C, 37.14; H, 4.90; N, 10.83. Found: C, 38.19; H, 3.82; N, 11.59.
12
13
3
2
2
2
2
2
.5. Synthesis of [NiCl (bi(pyridin-2-ylmethyl)amine]
2
By using NiCl .6H O (601.5 mg, 2.53 mmol). Blue precipitate was obtained and washed with
2
2
ethanol and dried overnight under vacuum. Yield: 0.85 g (77%). FT-IR: ν(H O), ν(NH), ν(C=N),
2
-1
ν(C=C) and ν(M-N) are 3420, 3242, disap., 1606, and 644 cm , respectively. Anal. calcd for
[
(C H N )Ni(H O)Cl]Cl.H O: C, 39.46; H, 4.65; N, 11. 51. Found: C, 40.32; H, 3.41; N, 12.18.
12 13 3 2 2
2
.6. Synthesis of [FeCl (bi(pyridin-2-ylmethyl)amine].
2
3
FeCl .2H O (408 mg, 2.524 mmol) in ethanol (5 cm ) was added to (bpma) (413.7 mg,
2
2
3
2
.53 mmol) in ethanol (10 cm ). After reacting for 30 minutes at room temperature, a brown
solid was precipitated. It was filtered, washed with ethanol and dried under vacuum. Yield: 0.75
g (82%). FT-IR: ν(H O),ν(NH), ν(C=N), ν(C=C) and ν(M-N) are 3415, 3248, disap., 1602 and
2
-1
6
42 cm , respectively. Anal. calcd for [C H N FeCl(H O)]Cl: C, 39.76; H, 4.69; N, 11.59.
12 13 3 2
Found: C, 40.81; H, 3.29; N, 12.67.
2
.7. Synthesis of [CoCl (bi(pyridin-2-ylmethyl)amine].
2
The violet compound was obtained from CoCl .3H O (375 mg, 2.04 mmol) as described
2
2
above. Yield: 0.67 g (76%). FT-IR: ν(NH), ν(C=N), ν(C=C) and ν(M-N) are 3294, disap., 1606,
-1
and 646 cm , respectively. Anal. calcd for [C H N CoCl ]: C, 43.75; H, 3.95; N, 12.76. Found:
12
13
3
2
C, 43.80; H,3.01; N, 13.59.
2
.8. Synthesis of [ZnBr (bi(pyridin-2-ylmethyl)amine].
2
The white compound was prepared as described above, using ZnBr .4H O (753.8 mg,
2
2
2
1
.538 mmol). Yield: 1.09 g (85%). FT-IR: ν(NH), ν(C=N), ν(C=C) and ν(M-N) are 3201, disap.,
-1
604, and 642 cm , respectively. Anal. calcd. for [C H N ZnBr ]: C, 34.00; H, 3.08; N, 9.88.
12
13
3
2
1
Found: C, 33.96; H, 3.09; N, 9.90. H-NMR (Suppl.Figure (2)): the signals found in the spectrum
at δ = 8.84 - 7.56 (m, 8H, pyridine-H), 4.18 (br, 4H, -CH ) and 3.57 (s, 1H, NH) can be assigned
2
to the aromatic, N-H and methylene protons, respectively.
5

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Results and Discussion
The pincer ligand bpma, is an example of a tridentate ligand with two identical pyridine
moieties.
1
bpma has a yellowish colour and was characterized by elemental analysis, infrared, H-NMR
spectroscopy. The ligand reacts easily at room temperature with salts of transition metals in the
formal oxidation state 2+ to yield compounds with compositions [Cu(HL)(H O) ]Cl .H O,
2
2
2
2
[
MCl(HL)(H O)]Cl.H O (M = Ni(II)(x = 1) and Fe(II) (x = 0)) and [M(HL)X ] (M = Co(II) (X =
2 2 2
Cl) and Zn(II)(X = Br)). The results of the elemental analysis of these stoichiometric complexes
are in agreement with the proposed molecular formulae (Scheme 2). It is obvious from these
formulae that the complexes have a trigonal bipyramidal structure [42,43].
Infrared spectra of HL and the effect of binding of Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)
ions on the vibration frequencies of the free ligand was considered as a useful technique to
elucidate the way by which bpma ligand bonds to the metal ions. The IR spectrum of the ligand
-1
shows a sharp and strong band at 1589 cm , which can be attributed to the vibration ν(C=N) of
the pyridine ring [38]. When the ligand is coordinated to metal ions, this band shifts to higher
-1
frequencies (13-17 cm ) indicating the involvement of the nitrogen atom of pyridine into the
coordination sphere. The in plane bending vibration δ(C=N) band of the bpma ligand is observed
-1
-1
at 620 cm and for the complexes at 642-650 cm which further support the coordination via
-1
pyridyl nitrogen [44]. The band observed at 3170 cm in attributed to the stretching vibration of
-1
-1
NH group. The shift in this band position from 100 cm to 24 cm in the complexes indicates
the participation of NH group in complex formation (Suppl. Fig(1)).
Reactions of bpma and transition metals in the oxidation state 2+ were carried out in
ethanol. Trigonal bipyramidal metal complexes were obtained with the three available
coordinating positions occupied by the unaltered N3 ligand and the other two positions occupied
1
by halide anions or water molecules [43]. A comparison of the H-NMR spectrum of the ligand
[
44] with that of its Zn(II) complex showed a downfield shift from δ = 8.76-7.52 ppm (m, 8H,
py) to δ = 8.84-7.56 (m, 8H, py) for the two signals of the pyridine moiety, respectively. The
methylene group shifts from δ = 3.72 (s, 4H, -CH ) in the free ligand to δ = 3.57 ppm (s, 4H, -
2
CH ) in the Zn(II) complex as a result of conformational change in the bpma skeleton due to
2
coordination of the bpma ligand to the metal ions. The NH group shifts from δ = 4.38 (s, 1H, -
NH) to δ = 4.18 ppm (s, 1H, -NH) as a result of coordination of the bpma ligand to the metal ions
6

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1
[
42]. Therefore, the results of H-NMR spectroscopy are in good agreement with the proposed
structures (Suppl. Fig (2)).
In the mass spectrum of Ni(II) complex the molecular ion peak was observed at m/z 365 which is
equivalent to its molecular mass (Suppl. Fig(3)).
Scheme 2. Structure of the complexes (M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II)).
In the present investigation, the weight loss for each chelate ligand was calculated within
the corresponding temperature ranges. The TG curve of [(C H N )Cu(H O) ] Cl .H O complex
1
2
13
3
2
2
2
2
exhibits an estimated mass loss of 3.61% (calcd. 4.64%) within the temperature range from 30 to
50 °C, which may be attributed to the liberation of water molecule. Between 150 and 800 °C
C H N (H O) Cl is subtracted under decomposition to 2HCl, coordinated water molecule and
1
12
13
3
2
2
2
7

ACCEPTED MANUSCRIPT
HL ligand. The estimated mass loss was found to be 75.08% (calcd. 74.87%). The residue
consists of CuO with estimated mass of 21.31% (calcd. 20.49%).
The TG curve of [(C H N )Ni(H O)Cl]Cl.H O complex shows two decomposition steps
1
2
13
3
2
2
within the temperature range from 30 to 750 °C. The first step of decomposition which occurs
from 30 to 250 °C corresponds to the loss of HCl molecule with a mass loss of 10.55% (calcd
1
0.00%). In the second stage (250-750 °C), the weight loss may be attributed to the loss of
ligand and HCl molecules (observed 69.63%, calcd 69.47%). Nickel oxide was left as residue
with an estimated percent of 19.82% (calcd.20.55%).
The TG curve of [C H N FeCl(H O)]Cl complex shows two decomposition steps
1
2
13
3
2
within the temperature range from 40 to 750 °C. The estimated mass loss between 40 and 355 °C
may attributed to the loss of HCl molecule. While, the other estimated weight loss between 355
and 750 °C may be attributed to the loss of HCl and the organic ligand molecules. The total
weight loss amounts to 79.63% (calcd. 79.11%). Finally, a residue of FeO (observed 20.36%,
calcd 20.89%) is observed (Suppl.Fig(4)).
The kinetic thermodynamic parameters such as activation energy (E*), enthalpy (∆H*),
entropy (∆S*) and free energy change (Gibbs free energy) of the decomposition (∆G*), were
evaluated graphically by employing the Coats–Redfern (CR) [45] and Horowitz–Metzger (HM)
[
46] methods.
The Coats-Redfern equation which is a typical integral method can be represented as:
A plot of left-hand side (LHS) against 1/T was drawn, E* is the energy of activation in kJ
-1
-1
mol and calculated from the slope and A in (s ) from the intercept. The entropy of activation
-1
-1
ꢀ
S* in (J K mol ) was calculated by using equation:
8

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Where K is the Boltzmann constant, h is the Plank’s constant and Ts is the DTG peak
B
temperature.
(b) Horowitz-Metzger equation
The Horowitz-Metzger equation is an illustrative of the approximation methods. These
authors derived the relation:
When n = 1, the LHS of equation 4 would be log[-log (1-α)]. For a first-order kinetic
process the Horowitz-Metzger equation may be written in the form:
Where θ = T-Ts, w = w –w, w = mass loss at the completion of the reaction; w = mass
γ
α
α
loss up to time t. The plot of log[log(wα /wγ)] versus θ was drawn and found to be linear from
the slope of which E* was calculated. The pre-exponential factor, A, was calculated from the
equation:
The entropy of activation, ꢀS*, enthalpy of activation, ꢀH* and Gibbs free energy, ꢀG*,
were calculated using the following equations;
ꢀH* = E*–RT
ꢀG* = ꢀH*–TꢀS*
The data were summarized in Table 1. The activation energies of decomposition were
-1
found to be in the range of 44.16-128.4 kJ mol . The high values of the activation energies
reflect the thermal stability of the metal complexes. The greater positive values of ∆H* indicate
that the processes may involve changes in translational, vibrational or rotational states or can
attributed to changes in mechanical potential energy for complexes. Also, according to the
kinetic data obtained, all of the complexes have negative entropy, which indicate that activated
complexes have more ordered systems than reactants [47, 48].
9

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In the present study, antibacterial activities of Cu(II), Ni(II), Fe(II), Co(II) and Zn(II)
complexes of btmp ligand were screened with the agar-cup method. DMSO was used as solvent
at a complex concentration of 20 ꢁg/mL. The chemicals were checked against Gram positive (B.
subtilis and st. aureus) and Gram negative (E.coli and P. aeruginosa) bacteria organisms
(Table1). It becomes obvious that the antibacterial activity follow the order Zn(II) = Co(II) >
Ni(II) > Cu(III) > Fe(II) > standard > bpma against B. subtilis. However, it follows the order of
Co(II) > Cu(II) > Ni(III) > Zn(II) > Fe(II) > standard > bpma with St. aureus. Finally, using (G-
bacteria), it is found that the antibacterial activity follow the order Zn(II) > Co(II) > Fe(II) =
Ni(II) > Cu(II) > standard > bpma with E. coli and followed the order Ni(II) > Zn(II) = Co(II) >
Cu(II) > Fe(II) > standard > bpma with P. aeruginosa (Table 2).
The data obtained for the metal complexes described above show that some of them have
the capacity of inhibiting the metabolic growth of the investigated bacteria. The activities of all
complexes tested may be explained on the basis of chelation theory. Chelation reduces the
polarity of the metal atom mainly because it partially shares its positive charge with the donor
groups and possible π electron delocalization takes place within the whole chelate ring. Also,
chelation increases the lipophilic nature of the central atom which subsequently favors its
permeation through the lipid layer of the cell membrane. It was described in literature that
lipophilic side chains may influence the interaction between molecules to lead to a degradation
of the bacteria cellular membrane and the leakage of cellular contents [49, 50].
Conclusions
The bpma ligand was synthesized and coordinated to several transition metal ions. It was
found to be meridionally coordinated with coordination number five for the metal ions. The
infrared spectra confirmed that bpma binds to the metal ions via the pyridine nitrogen atoms,
nitrogen- methylamine entity, one - two water molecules and/or one - two chloride or bromide
ions. The metal complexes showed antibacterial activities higher than the standard or ligand
compounds.
Acknowledgements
G.G. Mohamed thanks the Spanish Ministry of Education for financial support. This work was
partially supported by contracts PL972004 (European Union) and AMB1999-1810-CE (Spain).
1
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Table (1). Thermodynamic data of the thermal decomposition of metal complexes.
-1
-1
-1
-1
-1
Complex
Decomp.Temp.
E* (kJmol )
A (s )
∆S* (KJmol )
∆H* (kJmol )
∆G* (kJmol )
о
(
C)
6
8
[
[
[
C H N FeCl(H O)]Cl
40-355
44.16 (45.23)
1.23 (82.17)
2.89×10 (3.94x10 )
-102.3 (-103.7)
-160.3 (-161.2)
56.74 (55.47)
92.37 (92.89)
72.26 (73.98)
122.3 (123.7)
1
2
13
3
2
3
55-750
8
9
9
5
.04×10 (4.03x10 )
7
7
(C H N )Ni(H O)Cl]Cl.H O
30-250
68.47 (69.08)
28.4 (127.9)
3.41×10 (2.96 x10 )
-80.77 (-80.44)
-70.49 (-70.96)
34.62 (33.98)
134.2 (135.4)
33.47 (33.08)
104.6 (105.2)
1
2
13
3
2
2
2
50-750
1
9
9
3
.84×10 (3.77x10 )
8
8
(C H N )Cu(H O) ] Cl .H O
30-150
52.84 (54.09)
9.24 (98.88)
7.02×10 (6.76 x10 )
-118.4 (-119.5)
-154.1 (-155.0)
53.23 (54.60)
88.11 (87.96)
64.27 (62.95)
137.9 (136.4)
1
2
13
3
2
2
2
2
1
50-800
9
7
7
6
.42×10 (7.05x10 )
#
The data between parenthesis are obtained using Horowitz-Metzger equation while the data without parenthesis are obtained using Coats-Redfern equation.

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Table 2. Biological activity of the metal complexes tested using the diffusion agar technique. The inhibition zone diameter is given as
mm/mg sample (solvent: DMSO).
Metal complexes
G(+)
G(-)
Bacillus Staphylococcus Escherichia Pseudomonas
Coli
subtilis
0
aureus
0
aeruginosa
0
1
0
DMSO
btmp
6
17
30
42
29
15
12
2
8
[
[
[
[
CuCl (C H N )]
29
34
2
12 13
3
3
0
0
NiCl (C H N )]
35
30
2
12 13
3
3
FeCl (C H N )]
28
27
2
12 13
3
CoCl (C H N )]
39
35
34
40
40
2
12 13
3
4
3
5
[
ZnBr (C H N )]
39
30
2
12 13
3
2
20
Standard (amikacin)
22
25

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•
•
New tridentate acyclic pincer ligand have been Synthesized.
Preparation of Cu(II), Ni(II), Fe(III) ,Co(II)and Zn(II) [bi (pyridin-2-methyl)amine]
metal complexes have been illustrated.
•
•
Metal complexes showed high thermal stability.
Metal complexes showed high antibacterial activity.

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Suppl. Figure (1). FT-IR spectra of (a) Cu(II) and (b) Fe(II) complexes.

ACCEPTED MANUSCRIPT
1
Suppl. Figure (2). HNMR spectra of (a) ligand and (b) Zn(II) complex.

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Suppl. Figure (3). Mass spectrum of Ni(II) complex.

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Suppl.Figure (4). TGA curve of Fe(II) complex.