New metal complexes of N3 tridentate ligand: Synthesis, spectral studies and biological activity

Article abstract of DOI:10.1016/j.saa.2014.07.057

New tridentate ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2phenyl-2,3-dihydro-1H-pyrazol-4-ylazo}-phenol L was synthesized from the reaction of 1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine and 3.4-amino phenol. A complexes of these ligand [Ni(II)(L)(H₂O)₂Cl]Cl, [pt(IV)(L)Cl₃]Cl and [M(II)(L)Cl]Cl (M = Pd (II), Zn (II), Cd (II) and Hg (II) were synthesized. The complexes were characterized by spectroscopic methods and magnetic moment measurements, elemental analysis, metal content, Chloride containing and conductance. These studies revealed octahedral geometries for the Ni (II), pt (IV) complexes, square planar for Pd (II) complex and tetrahedral for the Zn (II), Cd(II) and Hg (II) complexes. The study of complexes formation via molar ratio and job method in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M:L) as (1:1). The thermodynamic parameters, such as ΔE^?, ΔH^?, ΔS^?ΔG^?and K are calculated from the TGA curve using Coats-Redfern method. Hyper Chem-8 program has been used to predict structural geometries of compounds in gas phase. The synthesized ligand and its metal complexes were screened for their biological activity against bacterial species, two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa).

Full text of DOI:10.1016/j.saa.2014.07.057

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
New metal complexes of N3 tridentate ligand: Synthesis, spectral
studies and biological activity
a
b,
⇑
Abbas Ali Salih Al-Hamdani , Wail Al Zoubi
a
Department of Chemistry, College of Science for Women University of Baghdad, Baghdad, Iraq
Department of Chemistry, College of Science, University of Damascus, Syria
b
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
The thermodynamic parameters, such
*
*
*
*
as
DE , DH , DS DG and K are
calculated from the TGA curve using
Coats–Redfern method of complex.
Hyper Chem-8 program has been
used to predict structural geometries
of compounds in gas phase.
The synthesized ligand and its metal
complexes were screened for their
biological activity against bacterial
species, two Gram positive bacteria
ꢀ
ꢀ
(
Bacillus subtilis and Staphylococcus
aureus) and two Gram negative
bacteria (Escherichia coli and
Pseudomonas aeruginosa).
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 May 2014
Received in revised form 2 July 2014
Accepted 18 July 2014
Available online 27 July 2014
New tridentate ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2phenyl-
2
,3-dihydro-1H-pyrazol-4-ylazo}-phenol L was synthesized from the reaction of 1,5-dimethyl-3-[2-(5-
methyl-1H-indol-3-yl)-ethylimino]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine and 3.4-amino phenol.
A complexes of these ligand [Ni(II)(L)(H O) Cl]Cl, [pt(IV)(L)Cl ]Cl and [M(II)(L)Cl]Cl (M = Pd (II), Zn (II),
2
2
3
Cd (II) and Hg (II) were synthesized. The complexes were characterized by spectroscopic methods and
magnetic moment measurements, elemental analysis, metal content, Chloride containing and conduc-
tance. These studies revealed octahedral geometries for the Ni (II), pt (IV) complexes, square planar for
Pd (II) complex and tetrahedral for the Zn (II), Cd(II) and Hg (II) complexes. The study of complexes
formation via molar ratio and job method in DMF solution has been investigated and results were con-
sistent to those found in the solid complexes with a ratio of (M:L) as (1:1). The thermodynamic param-
Keywords:
Tryptamine
Azo-Schiff base
Spectral studies
Biological activity
*
*
*
*
eters, such as
DE , DH , DS DG and K are calculated from the TGA curve using Coats–Redfern method.
Hyper Chem-8 program has been used to predict structural geometries of compounds in gas phase. The
synthesized ligand and its metal complexes were screened for their biological activity against bacterial
species, two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram negative
bacteria (Escherichia coli and Pseudomonas aeruginosa).
Ó 2014 Elsevier B.V. All rights reserved.
Introduction
The azo group possesses excellent donor properties and is
important in coordination chemistry [1,2], and some azo com-
pounds have been shown to possess good antibacterial activity
⇑
Corresponding author.
E-mail addresses: Abbas_alhamadani@yahoo.co.uk (A.A.S. Al-Hamdani),
wwailalzoubi@yahoo.com (W. Al Zoubi).
http://dx.doi.org/10.1016/j.saa.2014.07.057
1
386-1425/Ó 2014 Elsevier B.V. All rights reserved.

7
6
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
[
3–8]. Azo Schiff bases are commonly synthesized by coupling a
2
was dried over anhydrous CaCl in vacuum. Yield: 53.76%(0.95 g),
1
diazonium reagent with an aromatic aldehyde to form an azo alde-
hyde [9,10]. The azomethine group has good donor properties and
can form stable complexes with transition metal ions [11–13]. The
azo and azomethine groups on azo Schiff base ligand are oriented
in such a way that coordination of both groups to a metal ion is not
possible, thus, preferential coordination of the azomethine group
while the azo group is left free and uncoordinated has been
observed [14–17]. We reported herein the synthesis and spectro-
scopic studies as well as thermal investigation of novel Azo-Schiff
based ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-indol-
mp 177–179 °C. H NMR (DMSO-d6, ppm): d 1.89 (s, @CCH
2.10 (s, arom-CH ), 3.43 (s, NCH ), 3.30 (t, NCH ), 2.74 (t, CCH
7.64–8.08 (m, arom), 12.11 (s, NH), 4.10(s, NH
(100.622 MHz, DMSO-d ): d 16.39, 18.87, 38.79, 45.6, 58, 98, 100,
3
),
3
3
2
2
),
13
2
).
C NMR
6
110, 111, 118, 123, 127, 129, 130, 140, 146, 151, (MS) m/z 360,
164, 201.
Synthesis of the ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-
indol-3-yl)-ethylimino]-2phenyl-2,3-dihydro-1H-pyrazol-4-ylazo}-
phenol (L)
3
-yl)-ethylimino]-2phenyl-2,3-dihydro-1H-pyrazol-4-ylazo}-phenol.
1
3
1
C– H NMR spectra were obtained to determine the structure of
the ligand. The Ni(II), Pd(II), Pt(IV), Zn(II), Cd(II) and Hg(II) com-
plexes derived from Schiff base were also prepared and their struc-
tures were confirmed by elemental analysis, FT-IR spectroscopy,
UV–vis spectroscopy, thermogravimetric analysis and magnetic
moment measurements.
A mixture solution from H
and distilled water (10 ml), was charged with (A) (0.5 g,
1.39 mmol). An aqueous solution (2 ml) of NaNO (0.0144 g,
2 4
SO (18 M, 2 ml), ethanol (10 ml)
2
1 mmol) was added in drops while maintaining the temperature
between 0 and 5 °C to the mixture. After that the diazonium sul-
phate was added respectively with constant stirring to cold etha-
nolic solution of m-aminophenol (0.151 g, 0.00139 mol), and then
solution of 1 M NaOH (25 ml) was added to the dark colored mix-
ture. The mixture was stirred for 1 h at 0 °C and acidified with 1 mL
of conc. HCl. The brown product formed was suction filtered and
recrystallized from ethanol–water (1:1) and dried (Scheme 1).
Experimental
Materials and methods
All chemicals were obtained from commercial sources and were
1
6
Yield: 66.45% (0.44 g), mp > 390 °C. H NMR (DMSO-d , ppm):
used without further purifications (PdCl
HgCl , ZnCl , H ptCl O, NaNO , K CO
ꢁ6H
tryptamine hydrochloride, 4-aminophenazon m-aminophenol,
SO , and NaOH from Sigma–Aldrich. All solvents: C OH,
CHCl , DMSO, and DMF from Merck.
2
, NiCl
2
ꢁ6H
2
O, CdCl
2
ꢁH
2
O,
1
3 2
.89 (s, CACH ), 4.10 (s, NH ), 4.48 (s, OAH phenol), 12.1 (s,
2
2
2
6
2
2
2
3
from BDH. 5-Methyl-
NAH), 7.44 (m, C7,11-H), 7.85 (m, C9,18,21-H), 8.08 (m, C8,10-H). 13
C
6
NMR (100.622 MHz, DMSO-d ) d 16.39, 18.87, 39.36, 45.6, 58, 98,
H
2
4
2 5
H
1
1
00, 106, 110, 112, 119, 124, 126, 129, 130, 133, 140, 145, 153,
58, 168, 182, (MS) m/z 479, 323,160.
3
Physical measurements
General synthesis of the complexes
Elemental analyses (C, H and N) were carried out on a Heraeus
instrument (Vario EL). IR spectra were recorded as KBr or CsI discs
Ni (II), Cd (II), Zn (II), Hg (II), Pd (II) and Pt (IV) complexes were
prepared in a similar manner using the method described by Nejati
and Rezvani. Thus, a solution of 4 mmol of metal salts in 10 ml of
ethanol was added to an ethanol–chloroform (1:1 v/v) solution
containing 4 mmol of Ligand L and was refluxed for 6 h. The
obtained solution was left at room temperature. The resulting pre-
cipitates were filtered off, and washed with absolute ethanol and
then recrystallized from an ethanol–chloroform (1:3 v/v). Elemen-
tal analysis data, colors and yields for the complexes are given in
Table 1.
using a Shimadzu FT-IR-8300 spectrophotometer from 4000 to
ꢂ1
2
50 cm . Electronic spectra were measured from 200 to 900 nm
ꢂ3
for solutions (10 M) in DMF at 25 °C using a Shimadzu 160 spec-
trophotometer. Mass spectra were obtained by positive Electron-
Impact (EI) and Fast Atom Bombardment (FAB) was recorded on
a VG auto spec micromass spectrometer. NMR spectra were mea-
sured in DMSO-d6 solution using Brucker AMX400 MHz and Jeol
Lambda 400 MHz spectrometers and thermal analysis studies of
the ligand and complexes were performed on a Perkin–Elmer Pyris
Diamond DTA/TG thermal system under nitrogen atmosphere at a
heating rate of 10 °C/min from 25 to 700 °C. Metals were deter-
mined using a Shimadzu (A.A) 680 G atomic absorption spectro-
photometer. Chloride was determined using potentiometer
titration method on a 686-Titro processor-665Dosimat–Metrohm
Swiss. Conductivity measurements were made with DMF solutions
using a Jenway 4071 digital conductivity meter and room temper-
ature magnetic moments were measured with a magnetic suscep-
tibility balance (Jonson Mattey Catalytic System Division).
Microbiological investigations
The investigated isolates of bacteria were seeded in tubes with
3
nutrient broth (NB). The seeded NB (1 cm ) was homogenized in
3
the tubes with 9 cm of melted (45 °C) 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.
ꢂ5
3
After cooling on the formed solid medium, 2 ꢃ 10 dm of the
investigated compounds were applied using a micropipette. After
incubation for 24 h in a thermostat at 25–27 °C, the inhibition
Synthesis of the compound 1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-
yl)-ethyl imino]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine (A)
(
sterile) zone diameters (including disc) were measured and
An ethanolic solution (15 ml) of 5-methyltryptamine hydro-
chloride (1.036 g, 0.00492 mol) was added to a mixture containing
an ethanolic solution (25 ml) of 4-amino-1,5-dimethyl-2-phenyl-
expressed in mm. An inhibition zone diameter over 7 mm indicates
that the tested compound is active against the bacteria under
investigation. The antibacterial activities of the investigated com-
pounds were tested against Escherichia coli and Pseudomonas aeru-
ginosa as Gram negative, Bacillus subtilis and Staphylococcus aureus
as Gram positive. The concentration of each solution was
3
-pyrazol-5-one (1 g, 0.00492 mol). The reaction mixture was
heated on water bath at (40–50 °C for 14 h in presence of K CO
after the addition of excess of Ethanol (50 ml). The resulting mix-
ture was refluxed under N . A white solid was formed and then
recrystallized from mixture (water:ethanol) (1:1). The product
2
3
ꢂ3
3
2
1.0 ꢃ 10 mol dm . Commercial DMSO was employed to dissolve
the tested samples.

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
77
H
H
3
C
NH
2
H
N
H
3
C
NH2
N
N
O
N
C
EtONa/CH3COOH
Refluxe
H
3
C
N
H
C
N
3
N
H
2
N
CH
3
CH3
H 2SO4 / EtOH
OH
1
0%NaNO2
H
NSO4
N
NH2
3
H C
N
OH
N
H
H
C
3
C
N
NaOH
N
N
3
H C
N
N
N
N
H
3
N
2
H N
CH3
CH3
Scheme 1. Synthesis route of ligand.
Table 1
Colours, yields, elemental analyses, and molar conductance values.
Molar conductivity (cm2
X
ꢂ1
mol )
ꢂ1
Compound
Colour
Yield (%)
Found (Calc.) (%)
M
C
H
N
Cl
A
L
White
73.94
66.45
68
(73.51)
(7.01)
6.87
(6.10)
6.73
(5.16)
5.87
(4.75)
4.73
(4.41)
4.11
(3.89)
4.64
(4.45)
4.13
(3.58)
4.06
(19.48)
21.23
(20.44)
20.08
(15.20)
15.88
(15.92)
16.28
(14.79)
15.07
(13.05)
13.47
(14.93)
15.33
(12.01)
13.12
75.55
Violate
Brown
Yellow
Green
Red
Brown
Red
Brown
Violate
(70.12)
71.11
(52.12)
51.98
(54.61)
55.16
(50.73)
51.16
(44.78)
45.97
(51.19)
50.08
(41.19)
40.00
[
[
[
[
[
[
NiL(H
2
O)
2
Cl]Cl
(9.10)
10.11
(10.62)
11.08
(16.96)
17.35
(26.71)
(10.99)
9.98 = Cl
(11.51)
10.85 = Cl
(10.70)
11.24 = Cl
(9.44)
10.06 = Cl
(10.79)
5.89 = Cl
(17.37)
77
77
83
70
77
77
ZnLCl]Cl
CdLCl]Cl
HgLCl]Cl
PdLCl]Cl
75
58
79
2
7.77
Red
Brown
Brown
55
(16.20)
16.74
(23.89)
PtLCl
3
]Cl
59
2
4.08
16.42 = Cl
Programs used in theoretical calculation
i f
from the point T up to the reaction end point T on the TG curve, i.e.
the magnitude of the ordinate of a TG curve. The material released
at each step of the decomposition is identified by attributing the
mass loss (Dm) at a given step to the component of similar weight
calculated from the molecular formula of the investigated com-
plexes, comparing that with literatures of relevant compounds con-
sidering their temperature. This may assist identifying the
mechanism of reaction in the decomposition steps taking place in
the complexes under study. Activation energy (E) of the composi-
tion step: the integral method used is the Coats–Redfern equation
[20], for reaction order n – 1or n = 1, which when linearized for a
correctly chosen n yields the activation energy from the slop;
Hyper Chem-8 program is a sophisticated molecular modeler,
editor and powerful computational package that are known for
its quality, flexibility and ease of use. Uniting 2D visualization
and animation with quantum chemical calculations, molecular
mechanics and dynamic [18]. In the present work, parameteriza-
tion method 3(PM3) was used for the calculation of heat of forma-
tion and binding energy for all metal complexes. PM3 is more
popular than other semi-empirical methods due to the availability
of algorithms and more accurate than with other methods [19].
PM3/TM is an extension of the PM3 method to include orbital’s
for use with transition metals. It has parameterized primarily for
organic molecules and selected transition metals.
"
ꢂn#
ꢀ
ꢁ
1
1
ꢂ 1ð1 ꢂ
a
Þ
ZR
2RT
E
E
log
¼ log qE 1 ꢂ
ꢂ
n ¼ 1
n ¼ 1
2
T ð1 ꢂ nÞ
2:303RT
The thermal analysis
ꢀ
Þ:ꢁ
ꢀ
ꢁ
ꢂ log ꢁð1 ꢂ
a
AR
2RT
E
log ꢁ
¼ log ꢁ
ð1 ꢂ
ꢂ
From the TGA curves recorded for the successive steps in the
decomposition process of these ligand and complexes it was possi-
ble to determine the following characteristic thermal parameters
for each reaction step: Initial point temperature of decomposition
2
T
bE
E
2:303RT
*
*
*
H* ꢂTmax
D
D
S = 2.303R [log(Ah/K Tmax)],
D
H = E ꢂ RTmax
, DG = D
*
S . Where
a = fraction of weight loss, T = temperature (K), n = order
(
T
i
): the point at which TG curve starts deviating from its base line.
of reaction, A or Z = pre-exponential factor, R = molar gas constant,
E = activation energy and q = heating rate. Order of reaction (n): it
is the one for which a plot of the Coats–Redfern expression gives
the best straight line among various trial values of n that are exam-
ined relative to that estimated by the Horovitz–Metzger method
[21].
Final point temperature of decomposition (T ): the point at which
f
TG curve returns to its base line. Peak temperature, i.e. temperature
of maximum rate of weight loss (TDTG): the point obtained from
the intersection of tangents to the peak of TG curve. Mass loss at
the decomposition step (Dm): it is the amount of mass that extends

7
8
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
Table 2
IR frequencies (cm ) of the compounds.
ꢂ1
Compound
m
m
as(NH
s(NH
2
)
m
m
(OH) ph
(CO) ph
m
(NH)
m
(C@N)
m
m
(N@N) +
(CAN@NAC)
m
(CNNC)
m
(MAN)
Additional bands
2
)
2
d(NH )
A
L
3485
305
3439
330
3518
343
–
3271
1641
1670
1646
–
–
–
–
–
3
3530
1307
3546
1304
3115
1604
3124
1604
1446–1407
1115
1436–1403
1116
3
[
NiL(H
2
O)
2
Cl]Cl
500
470
m
d(H
(H
2
O) = 3643
O) = 969
3
2
m
m
(NiACl) = 415
(ZnACl) = 416
[
ZnLCl]Cl
CdLCl]Cl
3507
333
3512
343
3546
1304
3543
1303
3127
1604
3121
1643
1642
1436–1384
1107
1436–1390
1107
536
466
536
469
3
[
m
(CdACl) = 413
3
1
601
[
[
[
HgLCl]Cl
3518
343
3503
336
3518
343
3543
1308
3546
1307
3543
1308
3121
1601
3115
1604
3121
1601
1648
1646
1648
1436–1408
1107
1436–1403
1103
1436–1408
1107
536
469
530
465
536
469
m
m
m
(HgACl) = 413
(PdACl) = 420
(pt-Cl) = 413
3
PdLCl]Cl
3
PtLCl
3
]Cl
3
Ph = phenolic, as = asymmetric, s = symmetric.
Table 3
Magnetic moment and UV–vis spectral data in DMF solutions.
ꢂ1
max (cm
ꢂ1
ꢂ1
Complex
A
l
eff B.M
k
)
k
max (nm)
e
max (L mol cm
)
Assignments
*
35,714
3,333
36,630
3,333
33,783
0,769
33,670
6,246
12,658
280
300
273
300
296
325
297
381
790
492
410
380
280
324
340
394
490
650
289
505
790
35,000
36,900
36,900
39,800
3450
3500
2870
3400
370
p
n ?
p ?
n ?
?
p
p
p
p
p
*
3
*
L
*
3
*
[
[
[
ZnLCl]Cl
CdLCl]Cl
PdLCl]Cl
dia
dia
dia
p ?
*
*
3
ML ? CT and n ? p
*
p
? p
2
ML ? CT and n ?
p
1
g ? 1
g ? 1
A
A
1
A
2
g
g
m
2
1
1
2
2
2
0,325
4,390
6,315
350
1
B
1
m
2500
2800
3510
3960
130
160
40
45
740
M ? L(CT)
*
n ?
p ?
p
p
*
[
[
HgLCl]Cl
dia
35,714
0,864
29,411
*
3
ML ? CT and n ? p
*
NiL(H
2
O)
2
Cl]Cl
2.87
n ? p
2
2
1
5,380
0,408
5,384
M ? L(C.T)
3
g(F) ? 3
A
A
?
2
T
T
1
1
g(P)
g(F)
m
3
3
3
2
g(F) ?
m
2
*
[
pt LCl
3
]Cl
0.98
34,602
p
p
1
g ? 1
g ? 1
1
1
9,801
2,658
120
100
A
1
T
T
2
g
m
m
2
1
1
A
1
1
g
Scheme 2. Proposed structures of metal complexes.

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
79
Table 4
Thermal analysis data of some metal complexes of L.
Com
TG range (°C)
DTGmax (°C)
% Estimated (calculated)
Mass loss
Assignment
Total mass loss
L
32–165
77.83
312.17
531.33
13.802 (13.782)
58.094 (58.042)
30.260 (28.385)
102.156
(100.209)
C
C
C
5
H
6
ꢂ
1
3
65–383
83–598
17
H
19 4
N
ꢂ
6
H
6
N
3
O
[
PtLCl
3
]Cl
30–132
69.44
314
605.66
5.271(4.342)
22.821(22.842)
50.096(49.676)
78.188
(76.860)
Cl
1
32–430
30–700
3 8
C NH Cl
4
25 6 21
C N H
PtO
[
[
CdLCl]Cl
PdLCl]Cl
30–167
67–700
136.62
570.59
20.282(19.459)
61.015(61.188)
81.297
(80.647)
Cl + C
C H N
25 21 6
CdO
3 8
H N
1
25–210
129.48
305.34
566.05
15.223(15.211)
22.398(21.822)
44.824(44.349)
82.445
(81.382)
C
C
C
2
H
5 2
+ Cl
2
4
10–430
30–698
5
H
13
N
5
21
H
11
N
2
PdO
[
[
[
HgLCl]Cl
25–125
69.44
314
605.66
5.271(4.72)
22.821(22.460)
43.072(43.995)
71.164
(71.175)
Cl
1
4
25–430
30–698
C
C
7
H
H
7
N
N
22 4
3
Cl
21
HgO
NiL(H
2
O)
2
Cl]Cl
30–158
99.66
285.24
597.86
6.127(5.579)
21.601(22.163)
60.994(60.693)
88.722
(88.435)
2H
2
O
1
4
58–420
20–700
C
C
4
H10Cl
2
N
24
H
19
N
6
NiO
ZnLCl]Cl
25–148
72.03
7.647(8.363)
85.558
Cl + NH
2
1
4
48–425
25–695
359.39
476.91
31.601(32.094)
46.310(46.341)
(86.798)
C
C
5
H
13
N
5
21
H
11
N
2
ZnO
Table 5
Thermodynamic parameters of the ligand and metal complexes.
R2
Tmax (K)
Ea (kJ mol
ꢂ1
)
D *
H
(kJ mol
ꢂ1
)
A Sec ꢃ910
ꢂ1
7
D *
S
(J mol
ꢂ1 ꢂ1
K
)
D *
G (kJ mol )
ꢂ1
K ꢃ 10ꢂ7
Sam (step)
T range (°C)
n
L(1)
L(2)
L(3)
CdL = 1
CdL = 2
HgL1
HgL = 2
HgL = 3
ZnL = 1
ZnL = 2
ZnL = 3
NiL = 1
NiL = 2
NiL = 3
PdL = 1
PdL = 2
PtL = 1
PtL = 2
PtL = 3
32–165
1
1
1
0.997
0.996
0.998
0.994
0.986
0.998
0.993
0.997
0.997
0.994
0.998
0.997
0.995
0.998
0.995
0.996
0.998
0.995
0.997
350.98
582.32
804.45
409.77
843.74
342.59
587.15
878.81
345.18
632.54
750.06
372.81
558.39
871.01
402.63
578.49
342.59
587.15
878.81
6.569863
9.029516
11.77549
5.77655
10.73424
5.75888
8.58212
14.05864
5.96013
9.328938
13.87007
6.01307
9.016508
13.5233
9.90618
9.63113
5.7808
3.6518
4.188
2.808
430.8
967.2
ꢂ141.98
53.483
64.945
92.392
10.96674
0.149332
0.100132
0.11437
0.6349494
7.47118
0.17224
0.219906
7.26656
5.56647
0.12569
8.58393
0.13074
0.02748
4.37409
0.127159
0.117239
6.687478
0.24356
165–383
383–598
30–167
167–700
25–125
125–430
430–698
25–148
148–425
425–695
30–158
158–420
420–700
25–210
210–430
30–132
ꢂ104.336
ꢂ100.298
ꢂ107.9613
ꢂ95.086
11.7072
2.37031
3.71939
2.91059
3.70056
6.75222
3.09031
4.07
7.63407
2.91353
4.37405
6.28172
6.55872
4.82156
2.9325
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
0.9
1.96163
18.9976
1.48445
4.50492
10.1629
1.53688
15.9378
6.6931
1.71005
3.90937
89.7638
2.60789
4.18393
2.34722
2.99936
10.6594
46.6096
83.9477
40.1809
64.786
95.1843
40.5644
75.7357
84.7274
43.295
62.8934
78.0861
49.0149
65.291
38.8976
69.4054
94.4377
ꢂ108.79
ꢂ104.0388
ꢂ100.6270
ꢂ108.564
ꢂ113.2983
ꢂ102.7828
ꢂ108.3165
ꢂ104.8002
ꢂ82.438
ꢂ105.4471
ꢂ104.5299
ꢂ104.98
132–430
430–700
11.19325
13.6607
6.33296
6.35428
ꢂ107.4213
ꢂ100.2304
Results and discussion
complexes are air-stable solids, soluble in DMF and DMSO, spar-
ingly soluble in MeOH, CHCl , CH Cl and not soluble in other com-
3
2
2
The new N3 tridentate ligand L was obtained in good yield by the
reaction of 1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimi-
no]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine and 3.4-amino
phenol, Scheme 1. The ligand was characterized by elemental anal-
ysis (Table 1), IR (Table 2), UV–vis (Table 3) respectively. Mono-
meric complexes of the ligand with Pd(II), Ni(II), pt(IV), Zn(II),
Cd(II) and Hg(II) were synthesized by heating 1 mmol of each ligand
with 1 mmol of metal chloride, using ethanolic solution. However,
in ethanolic, deprotonation of the ligand occur facilitating the for-
mon organic solvents. The analytical data Table 1 agree well with
the suggested formulae. The most important infrared bands of the
ligand and their complexes together with their assignments are col-
lected in Table 2.
IR spectra
The IR spectrum of the compound A, L and complexes show
ꢂ1
bands at 3439, 3330 and 1670 cm due to the as
m
(NH ), s
2
m
(NH2),
mation of the complexes [Ni(II)(L)(H
2
O)
2
3
Cl]Cl, [pt(IV)(L)Cl ]Cl and
d(NH ), and
m
(C@N) functional groups, respectively. The ligand
2
ꢂ1
[
M(II)(L)Cl]Cl (M = Pd(II), Zn(II), Cd(II) and Hg(II)) Scheme 2. The
show characterization bands at 3530, 1307 and 1446 cm due to

8
0
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
Table 6
Antibacterial activity data of ligand and its complexes inhibition zone (mm).
ꢂ
ꢂ
Compound
L
Bacillus subtilis G+
Staphylococcus aureus G+
Escherichia coli G
Pseudomonas aeruginosa G
20
22
24
20
22
24
20
17
20
22
22
20
22
26
19
22
22
16
22
24
16
16
18
22
21
18
22
28
[
[
[
[
[
[
2 2
NiL(H O) Cl]Cl
ZnLCl]Cl
CdLCl]Cl
HgLCl]Cl
PdLCl]Cl
3
PtLCl ]Cl
Key to interpretation: less than 10 mm = inactive, 10–15 mm = weakly active, 15–20 mm = moderately active, more than 20 mm = highly active.
Table 7
Comparison of experimental and theoretical vibration frequencies for ligand.
Com
as
m
2
(NH )
(NH
2
)m
s
m
(C@N)
m
(CAN)
m
(N@N)
m
(C@C)
m
(NH)
d(NH
2
)
m
(OH)
m
(OH)
m
(CAO)
Phenol
Carboxylic
Phenol
A
3485*
3305*
1641–1633*
1243*
1591–1556*
3271*
1612*
3699*
3429*
3885
1288*
*
*
**
**
**
**
**
**
**
**
**
3
0
504
3382
1867
1249
1832
3452
1021
0.003
3890
1412
*
**
***
***
***
***
***
***
***
***
***
0
ꢂ0.001
0
ꢂ0.001
1550–1496*
0
0
ꢂ0.001
0
L
3330*
3330*
1670*
1224*
1077*
3115*
1604*
–
3400*
1203*
*
*
**
**
**
**
**
**
**
**
**
3
0
477
3405
0
1934
1057
0.001
1911
0.007
1829–1514
3405
0
1206
0.001
3684
0
1307
0
*
**
***
***
***
***
****
***
***
***
***
ꢂ0.001
ꢂ0.001
the
m(OH) phenolic,
m
(CAO) phenolic and
m(N@N), functional
p ? p
*. Moreover, the spectrum of the complexes also shows
groups, respectively. The IR spectra of the complexes exhibited
ligand bands with the appropriate shifts due complexes formation
Table 2 [22,23].
bands at 325, 381 and 324 nm due to the charge transfer as the
electronic configuration of these complexes Zn (II), Cd (II) and Hg
(II) respectively, confirmed the absence of any d-d transition
[26,27]. The magnetic moment value 2.75 B.M of Ni(II) complex
Moreover, the
m(C@N), m(N@N), bands of the ligand was
ꢂ1
3
3
observed at 1670, 1446 cm and this band was shifted to the lower
frequencies by (28–22 cm ) for
the ligand was observed at 1446 cm and this band was shifted to
exhibits peaks at (650 and 490) nm which assign to A2g ? T1g(F)
ꢂ1
3
3
m
(C@N), and the
m(N@N), bands of
and A2g ? T1g(P) transition, respectively suggesting an octahe-
ꢂ1
dral geometry around the Ni(II) ion. The magnetic moment value
of this complex is consistent with octahedral geometry structure.
ꢂ1
the lower frequencies by (10 cm ), in the spectra of the com-
plexes. This indicates that the ligand was coordinated with the
The spectrum of pt(IV) complex of together with the
leff value
2
metal ions through the N atom. So, it is noted both of the m(NH )
Table 3 exhibits peaks at (790 and 505) nm which assign to
A1g ? T1g and A1g ? T2g transition, respectively suggest octahe-
1
1
1
1
asymmetric and symmetric band of the ligand exhibited at 3439
ꢂ1
and 3330 cm this band was shifted to the high frequencies by
dral geometry around pt(VI) complex. The spectrum of Pd(II) com-
ꢂ1
ꢂ1
*
1
1
(
79–68 cm ) and (3–13 cm ) for as
m(NH
2
) and s
m
(NH
2
), in the
plex gave band assigned to n ?
p
, M ? L (C.T),
A
1g ? B1g. and
1
1
spectra of the complexes. This indicates that the ligand was coor-
dinated with the metal ions through the N atom. The reduction
in bond order, upon complexation, can be attributed to delocaliza-
A1g ? A2g (380, 410, 492 and 790) nm respectively suggesting
an square planer geometry around the Pd(II) ion. The magnetic
moment value of this complex is consistent with square planer
geometry [26].
2
tion of metal electron density (t g) to the p-system of the ligand.
These shifts confirm the coordination of the ligand via the nitrogen
The metal ions complexes discussed herein were dissolved in
DMSO and the molar conductivities of their 10 M solutions at room
temperature were measured to establish the charge of the metal
complexes. The range of conductance values listed in Table 1 indi-
cates that all the metal complexes have are [1:1] electrolytes [28].
ꢂ3
of azomethine and the azo groups to metal ions.
ꢂ1
The
m
(NH) band at 3234 cm in the free ligand was not shifting
for the complexes. At lower frequency the complexes exhibited
ꢂ1
bands around 536–469 cm assigned to the
m
(MAN) and exhib-
ꢂ1
ited bands around 413–420 cm assigned to the
plexes and new bands in [NiL(H
and 969 cm assigned to the
m
(M-Cl) for com-
ꢂ1
2
O)
(H
2
Cl]Cl complex the 3643 cm
O) and d(H
Mass spectrum
ꢂ1
m
2
2
O) This indicates
that the ligand was coordinated with the Ni(II) ion through the
Compound (A)
2
H O atom [24,25].
The electron impact spectrum of compound (A) confirms the
probable formula by showing a peak at 360 m/z, corresponding
to Schiff base moiety [(C22
The series of peaks at 164 m/z is attributed to (C11
01 m/z attributed to (C11 ). Their intensity gives an idea of
25 5
H N ), calculated atomic mass 360].
Electronic spectra studies
+
H18N) and at
2
13 4
H N
The electronic spectra of the free ligand L shows electronic tran-
*
*
the stability of fragments.
sitions
p ? p and n ? p at 280 and 300 nm respectively. Finally,
the diamagnetic of Zn(II), Cd(II) and Hg(II) complexes exhibited
*
absorption bands at 296, 297 and 280 nm due to
p
?
p
. Appear-
Ligand (L)
*
ance of these band are due to n ?
p
transition associated with
The electron impact spectrum of the ligand (L) confirms the
azomethine linkage and M ? L (C.T) charge transfer transition.
probable formula by showing a peak at 479 m/z, corresponding
Moreover, the absorption bands at 296, 297 and 280 nm due to
29 7
to Schiff base-Azo moiety [(C28H N O), calculated atomic mass

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
81
as ν (NH
2
)
ν (NH)
s ν (NH
2
)
3
ν (CH )
ν (CH
3
)
ν (C=N)
δ (NH
2
)
ν (C-N)
ν (N-Ar)
ν (C=C)
ν (N-N)
ν (C-N)
(a)
Fig. 1. The calculated vibrational frequencies of starting material A (a) and ligand L new metal complexes of N3 tridentate ligand: synthesis, spectral (b).
4
79]. The series of peaks in the range of 323 and 160 m/z may be
Complex of CdL
assigned to various fragments. Their intensity gives an idea of
the stability of fragments.
The electron impact spectrum of [CdL
2
Cl]Cl confirms the prob-
able formula by showing a peak at 662.9 m/z, corresponding to
Complex moiety [(C28 CdOCl ), calculated atomic mass
H
29
N
7
2
Complex of ZnL
662.9]. The series of peaks in the range of 430.3, 429.3, 205.2 and
The electron impact spectrum of [ZnL
able formula by showing a peak at 615.9 m/z, corresponding to
Complex moiety [(C28 ZnOCl ), calculated atomic mass
15.9]. The series of peaks in the range of 430.3, 429.3, 205.2 and
04.3 m/z may be assigned to various fragments.
2
Cl] Cl confirms the prob-
204.3 m/z may be assigned to various fragments.
H
29
N
7
2
Complex of HgL
6
2
The electron impact spectrum of [HgL
2
Cl]Cl confirms the
probable formula by showing a peak at 751 m/z, corresponding

8
2
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
ν (C=N)
ν (N=N)
ν (O-H)
2
asν (NH )
sν (NH
2
)
3
ν (CH )
ν (N-H)
δ (NH2)
ν (C=C)
ν (C-N)
(b)
Fig. 1 (continued)
to Complex moiety [(C28
7
3
H
29
N
7
HgOCl
51]. The series of peaks in the range of 682, 640, 617, 549, 443,
60, 216, 144, 106 and 69 m/z may be assigned to various
2
), calculated atomic mass
Complex of PtL
2 3
The electron impact spectrum of [ptL Cl ] Cl confirms the prob-
able formula by showing a peak at 816 m/z, corresponding to Com-
plex moiety [(C28 PtO Cl ), calculated atomic mass 816]. The
fragments.
H
29
N
7
3
4
series of peaks in the range of 682, 640, 549, 532, 500, 428, 403,
232, 211, 171, 134, 91 and 72 m/z may be assigned to various
fragments.
Complex of PdL
2
The electron impact spectrum of [PdL Cl]Cl confirms the proba-
ble formula by showing a peak at 656 m/z, corresponding to Com-
plex moiety [(C28 PdOCl ), calculated atomic mass 656]. The
series of peaks in the range of 369, 354, 296, 287, 208, 128, 125,
22, 88 and 78 m/z may be assigned to various fragments.
H
29
N
7
2
Molar ratio
1
Complex formation by molar ratio of ligand to metal ion was
also studied in DMF solution. A series of solutions containing con-
ꢂ3
Complex of NiL
stant concentration of metal ion (1 ꢃ 10 M) were treated with
The electron impact spectrum of [NiL
Cl(H O)
2 2 2
]Cl confirms the
the same volumes of various concentrations of ligand in presence
of potassium hydroxide and heated at 100 °C. The results of L:M
titrations were obtained by plotting absorbance of solution mix-
tures at kmax of the complexes against [L]/[M] which showed a
1:1 M:L ratio for all the complexes, as observed for the solid state
probable formula by showing a peak at 642 m/z, corresponding
to Complex moiety [(C28 NiO Cl ), calculated atomic mass
42]. The series of peaks in the range of 369, 354, 276,261,241,
85, 111, 93, 75 and 56 m/z may be assigned to various fragments.
H
33
N
7
3
2
6
1

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
83
Electrostatic Potential (A)
HOMO=-0.020550 eV (A)
LUMO= -8.122651 eV (A)
Electrostatic Potential L
HOMO=-8.295629 eV
LUMO=0.142872 eV
Fig. 2. HOMO and electrostatic potential as for starting material and L.
Table 8
ꢂ1
Conformation energetic in (K J Mol ) for the starting material (A), ligand and complexes.
Com
PM3
AM1
A
Total energy in (0 °K)
Total energy in (345.51 °K)
Binding energy
Heat of formation
Electronic energy
Free energy
Total Dipole moment
Zero point energy of vibration
Kinetic energy in (345.51 °K)
Total energy in (0 °K)
Total energy in (148.73 °K)
Binding Energy
Heat of formation
Electronic energy
Free energy
Total dpole moment
Zero point energy of vibration
Kinetic energy
Binding energy
Heat of formation
Binding energy
Heat of formation
Binding energy
Heat of formation
Binding energy
Heat of formation
Binding energy
Heat of formation
ꢂ87618.9217849
ꢂ5430.5535
ꢂ96523.8785396
ꢂ5272.7704
ꢂ5484.108206
143.0217934
ꢂ761635.0472123
ꢂ5430.5535
ꢂ5320.1141276
307.0158724
ꢂ712416.7481261
ꢂ5272.7704
3.69133
269.87871
53.5547
ꢂ119697.7271634
ꢂ119697.7271634
ꢂ7017.1381464
129.2988536
ꢂ1234339.9376185
ꢂ119,667
3.67133
268.37399
47.3438
L
ꢂ132546.4762082
ꢂ132546.4762082
ꢂ6949.6286402
196.8083598
ꢂ1211126.0366310
ꢂ6890.62
4.44357 Debyes
328.06184
28.8175 in (148.73°K)
ꢂ533.2705542
20.3804458
ꢂ7067.0140643
146.3109357
ꢂ6945.1459229
209.3490771
ꢂ6890.9845825
259.0604175
ꢂ6945.7550429
192.2599571
5.9931Debyes
340.12568
30.2162 in (155.95 °K)
NiL
PdL
ZnL
CdL
HgL

8
4
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
Length of the bond for (A) PM3
A
order of the bond for (A) AM1
order of the bond for (A) PM3
Length of the bond for (A) AM1
L
order of the bond for (L) AM1
Length of the bond for (L) AM1
Fig. 3. conformation structure, bond length of A, ligand and complexes.
Thermal analysis
The results of thermo gravimetric analyses of L and metals com-
plexes are given in Table 4. The thermograms have been carried out
in the range of 25–700 °C at a heating rate of 10 °C/min in nitrogen
atmosphere, they showed an agreement in weight loss between
their results obtained from the thermal decomposition and the cal-
culated values, which supports the results of elemental analysis
and confirms the suggested formulae. Thus, the ligand L showed
a common general behavior as the first step (C28
29 7
H N O) was loss
of C O moiety followed by the other parts of the ligand, the
6 6 3
H N
final step of the thermolysis reactions of the complexes was found
to give the metal oxide (see Table 5).
(
L)-C28
(
(
H
29
N
7
O [102.156% Found (100.209% Cal)]
32–165 °C) ? C [13.802% Found (13.782% Cal)]
165–383 °C) ? C17
5 6
H
-
H
19
N
4
[13.802% Found (13.782%
O[30.260% Found (28.385%Cal)
1
2 2 2 2 2 2
-[ZnL Cl]Cl, 2-[CdL Cl]Cl, 3-[NiL (H O) Cl]Cl,4-[PdL Cl]Cl
Cal)](383–598 °C) ? C
6 6
H N
3

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
85
order of the bond for (L) PM3
Length of the bond for (L) PM3
PdL
HgL
CdL
ZnL
Fig. 3 (continued)
1
2
3
-C28
[
H
29
N
7
OCl
20.282% Found (19.459%Cal)]
OCd (533.896) (167–700 °C) ? C25
2
Cd (662.89) (30–167 °C) ? Cl + C
3
H
8
N
1-C28
Found (15.211%Cal)]
2-C26 OPd (556.976) (210–430 °C) ? C
Found (21.822%Cal)]
3-C21 OPd (413.626) (430–698 °C) ? C21
Found (44.349%Cal)]
H
29
N
7
OCl
2
Pd (656.9) (25–210 °C) ? C
2
H
5
+ Cl [15.223%
[22.398%
[44.824%
-C25H
21
N
6
H
21
N
6
[61.015%
H
24
N
7
5
H
13 5
N
Found (61.188%Cal)]
-CdO [19.371% Found (19.352%Cal)]
H
11
N
2
H
11
N
2
Total wt. loos = 81.297% Found (80.647% Cal) and final
residue: 18.703% Found (19.371% Cal)
(continued on next page)

8
6
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
NiL
ZnL
Fig. 3 (continued)
3
-PdO [18.632% Found (17.555%Cal)]
[31.601% Found (32.094%Cal)]
13 4
3-C18 OZn (366.716) (425–695 °C) ? C18H N [46.310%
Found (46.341%Cal)]
Total wt. loos = 82.445% Found (81.382% Cal) and final
residue: 18.618% Found (18.632% Cal)
H
13
N
4
4
-ZnO [13.211% Found (13.202%Cal)]
Total wt. loos = 85.558% Found (86.798% Cal) and final
residue: 14.442% Found (13.211% Cal)
1
2
3
4
-C28
H
33
N
7
O
3
Cl
Found (5.579%Cal)]
OCl Ni (609.21) (158–420 °C) ? C
21.601% Found (22.163% Cal)]
ONi (466.206) (420–700 °C) ? C24
2
Ni (645.21) (30–158 °C) ? 2H
2
O [6.127%
10NCl
[60.994%
-C28H
29
N
7
2
4
H
2
[
1-C28H29N OCl Pt (816) (30–132 °C) ? Cl [5.271% Found
7
4
-C24H
19
N
6
H
19
N
6
(4.342%Cal)]
Found (60.693% Cal)
-NiO [11.577% Found (11.564% Cal)]
7 3 3 8 3
2-C28H29N OCl Pt (781.048) (132–430 °C) ? C H Cl N
[22.821% Found (22.842%Cal)]
Total wt. loos = 88.722% Found (88.435% Cal) and final
residue:11.278% Found (11.577% Cal)
3-C25H21N OPt (594.542) (430–700 °C) ? C25H21N [50.096%
Found (49.676%Cal)]
6
6
4
-ptO [25.852% Found (23.139%Cal)]
Total wt. loos = 78.188% Found (76.860% Cal) and final
residue: 21.812% Found (25.852% Cal)
1
2
3
4
-C28
(
H
29
N
7
OCl
4.720%Cal)]
OClHg (715.648) (125–430 °C) ? C NCl
22.821% Found (22.460%Cal)]
22 4
OHg (546.946) (430–698 °C) ? C21H N [43.072%
2
Hg (751.1) (25–125 °C) ? Cl [5.271% Found
-C28H
29
N
7
7
H
7
[
-C21H
22
N
4
Microbiological investigation
Found (43.995%Cal)]
-HgO [28.836% Found (28.825%Cal)]
The biological activity of L ligand and its complexes were tested
against bacteria; we used more than one test organism to increase
the chance of detecting antibiotic principles in tested materials.
The organisms used in the present investigation included two
Gram positive bacteria (B. subtilis and S. aureus) and two Gram neg-
ative bacteria (E. coli and P. aeruginosa). The results of the bacteri-
cidal screening of the synthesized compounds are recorded in
Total wt. loos = 71.164% Found (71.175% Cal) and final
residue: 28.836% Found (28.836% Cal)
1
2
-C28
H
29
N
7
OCl
Found (8.363%Cal)]
OClZn (564.388) (148–425 °C) ? C10
2
Zn (615.9) (25–148 °C) ? Cl + NH
2
[7.647%
Cl
-C28
H
27
N
6
H
14
N
2

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
87
CdL
HgL
Fig. 3 (continued)
Table 6. An influence of the central ion of the complexes in the
antibacterial activity against the tested Gram positive and Gram
negative organisms show that the complexes have an enhanced
activity compared to the ligand itself.
reported [29] that frequencies coupled with Hartree–Fock Theory
(HFT) approximation and a quantum harmonic oscillator approxi-
mation tends to be 10% too high.
Electrostatic potential (E.P)
Theoretical study
Electron distribution governs the electrostatic potential of mol-
ecules and describes the interaction of energy of the molecular sys-
tem with a positive point charge, so it is useful for finding sites of
reaction in a molecular positive charged species tend to attack a
molecule where the E.P. is strongly negative electrophilic attach.
The E.P of free ligands ware calculated and plotted as 2D contour
to investigate the reactive sites of the molecules, and one can inter-
pret the stereochemistry and rates of many reactive involving soft
The vibration spectra of the A and Azo-schiff base L were calcu-
lated by using a semi-empirical (PM3 and AM1) method. The
results obtained for wave numbers are presented in Table 7,
Fig. 1 and the comparison with the experimental values indicates
some deviations. These deviations may be due to the harmonic
oscillator approximation and lack of electron correlation. It was

8
8
A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
PdL
NiL
Fig. 3 (continued)
electrophiles and nucleophiles in terms of the properties of frontier
orbitals (HOMO and LUMO). Overlap between the HOMO and
LUMO values were plotted as 2D contour to get more information
about these molecules Fig. 2. The results of calculation showed that
the LUMO of transition metal ion prefers to react with the HOMO
of nitrogen atoms of Azo-Schiff base ligand.
Conclusion
In this paper we have explored the synthesis and coordination
chemistry of some monomeric complexes obtained from the reac-
tion of the tridentate ligand L with some metal ions. The mode of
bonding and overall structure of the complexes were determined
through physico-chemical and spectroscopic methods. Complexes
formation study via molar ratio has been investigated and results
were consistent to those found in the solid complexes with a ratio
Optimized geometries energy of compounds
*
*
of (M:L) as (1:1). The thermodynamic parameters, such as
D
E ,
DH ,
A theoretically probable structures of A metal complexes with
Azo Schiff base were calculated to search for the most probable
model building stable structure, these shapes, show the calculated
optima geometries for A and Azo-schiff base L. The results of PM3
and AM1 method of calculation in gas phase for the binding ener-
gies and heat of formation of complexes are described in Table 8.
Show the conformation structure, bond length of A, ligand and
complexes Fig. 3.
*
*
DS DG and K are calculated from the TGA curve using Coats–Red-
fern method. Hyper Chem-8 program was used to predict struc-
tural geometries of compounds in gas phase. The heat of
formation (DHf°) and binding energy (DEb) at 298 K for the A, free
ligand and its complexes was calculated by PM3 method. The syn-
thesized ligand and its metal complexes were screened for their
biological activity against bacterial species, two Gram positive

A.A.S. Al-Hamdani, W. Al Zoubi / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 75–89
89
bacteria (B. subtilis and S. aureus) and two Gram negative bacteria
E. coli and P. aeruginosa.
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